Proceedings of International Conference on Technology and Instrumentation in Particle Physics 2017

Springer Proceedings in Physics 213

Zhen-An Liu Editor

Proceedings of International Conference on Technology and Instrumentation in Particle Physics 2017 Volume 2

Springer Proceedings in Physics Volume 213

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Zhen-An Liu Editor

Proceedings of International Conference on Technology and Instrumentation in Particle Physics 2017 Volume 2

123

Editor Zhen-An Liu Institute of High Energy Physics Chinese Academy of Sciences Beijing, China

ISSN 0930-8989 ISSN 1867-4941 (electronic) Springer Proceedings in Physics ISBN 978-981-13-1315-8 ISBN 978-981-13-1316-5 (eBook) https://doi.org/10.1007/978-981-13-1316-5 Library of Congress Control Number: 2018947450 © Springer Nature Singapore Pte Ltd. 2018 This work is subject to copyright. All rights are reserved by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. The publisher, the authors and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publisher nor the authors or the editors give a warranty, express or implied, with respect to the material contained herein or for any errors or omissions that may have been made. The publisher remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. This Springer imprint is published by the registered company Springer Nature Singapore Pte Ltd. The registered company address is: 152 Beach Road, #21-01/04 Gateway East, Singapore 189721, Singapore

Contents

Calorimeters High Granularity Digital Si-W Electromagnetic Calorimeter for Forward Direct Photon Measurements at LHC . . . . . . . . . . . . . . . . Hongkai Wang, for the ALICE-FoCal Collabration

3

The CMS High-Granularity Calorimeter for Operation at the High-Luminosity LHC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Florian Pitters, On behalf of the CMS collaboration

7

Performance Study for the CEPC ScW ECAL . . . . . . . . . . . . . . . . . . . . Hang Zhao, Zhi-gang Wang, Peng Hu, Tao Hu, Sen Qian, Ming-hui Li, and Li-shuang Ma Development of ATLAS Liquid Argon Calorimeter Readout Electronics for the HL-LHC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Maximilian Hils, On behalf of the ATLAS Liquid Argon Calorimeter Group

12

17

Upgrade of the ATLAS Tile Calorimeter for the High Luminosity LHC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . F. Tang, on behalf of the ATLAS Tile Calorimeter System

22

Calibration and Performance of the ATLAS Tile Calorimeter During the Run 2 of the LHC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Oleg Solovyanov, on behalf of the ATLAS Collaboration

31

Performance Studies and Requirements on the Calorimeters for a FCC-hh Experiment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C. Neubüser, on behalf of the FCC-hh Detector Working Group

37

v

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Contents

Precision Timing Calorimetry with the Upgraded CMS Crystal ECAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Adi Bornheim, on behalf of the CMS Collaboration

44

Construction and First Beam-Tests of Silicon-Tungsten Prototype Modules for the CMS High Granularity Calorimeter for HL-LHC . . . . Francesco Romeo, On behalf of the CMS collaboration

49

Precision Timing Detectors with Cadmium Telluride Sensors . . . . . . . . Adi Bornheim, Jiajing Mao, Aashrita Mangu, Cristian Pena, Maria Spiropulu, Si Xie, and Zhicai Zhang Prototype Tests for a Highly Granular Scintillator-Based Hadronic Calorimeter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Yong Liu, for the CALICE Collaboration Design, Status and Perspective of the Mu2e Crystal Calorimeter . . . . . . G. Pezzullo, N. Atanov, V. Baranov, J. Budagov, F. Cervelli, F. Colao, E. Diociaiuti, M. Cordelli, G. Corradi, E. Danè, Yu. Davydov, S. Donati, R. Donghia, S. Di Falco, B. Echenard, L. Morescalchi, S. Giovannella, V. Glagolev, F. Grancagnolo, F. Happacher, D. Hitlin, M. Martini, S. Miscetti, T. Miyashita, L. Morescalchi, P. Murat, E. Pedreschi, F. Porter, F. Raffaelli, M. Ricci, A. Saputi, I. Sarra, F. Spinella, G. Tassielli, V. Tereshchenko, and R. Y. Zhu

56

61 66

Applications of Very Fast Inorganic Crystal Scintillators in Future HEP Experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ren-Yuan Zhu

70

Liquid Xenon Detector with VUV-Sensitive MPPCs for MEG II Experiment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Shinji Ogawa, on behalf of the MEG II Collaboration

76

Electromagnetic Calorimeter Prototype for the SoLID Project at Jefferson Lab . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Y. Tian, J.-P. Chen, C. Feng, J. Jiao, A. Li, Y. Yu, and X. Zheng

80

A Si-PAD and Tungsten Based Electromagnetic Calorimeter for the Forward Direct Photon Measurement at LHC . . . . . . . . . . . . . . Yota Kawamura, for the ALICE FoCal Collaboration

86

Dark Matter Detectors Nuclear Emulsion Based Detector for Directional Dark Mater Search . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ali Murat Güler

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Contents

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Dark Matter Search with Superconducting Detector . . . . . . . . . . . . . . . Keishi Hosokawa, Koji Ishidoshiro, Atsushi Suzuki, Satoru Mima, and Yasuhiro Kishimoto

97

Preliminary Calibration of Spherical Proportional Counter for Low Energy Nuclear Recoils . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101 Haiqiong Zhang, Zhimin Wang, Charling Tao, Changjiang Dai, Ning Zhou, Yi Tao, Ruoqing Liu, Chenyang Tang, and Changgen Yang Gaseous Detectors Simulation and Investigation of the Gaseous Detector Module for CEPC-TPC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109 Haiyun Wang, Huirong Qi, Yulian Zhang, and Zhiwen Wen A Cylindrical GEM Inner Tracker for the BESIII Experiment At IHEP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116 R. Farinelli, M. Alexeev, A. Amoroso, F. Bianchi, M. Bertani, D. Bettoni, N. Canale, A. Calcaterra, V. Carassiti, S. Cerioni, J. Chai, S. Chiozzi, G. Cibinetto, A. Cotta Ramusino, F. Cossio, F. De Mori, M. Destefanis, T. Edisher, F. Evangelisti, L. Fava, G. Felici, E. Fioravanti, I. Garzia, M. Gatta, M. Greco, D. Jing, L. Lavezzi, C. Leng, H. Li, M. Maggiora, R. Malaguti, S. Marcello, M. Melchiorri, G. Mezzadri, G. Morello, S. Pacetti, P. Patteri, J. Pellegrino, A. Rivetti, M. D. Rolo, M. Savrie, M. Scodeggio, E. Soldani, S. Sosio, S. Spataro, and L. Yang Upgrade of the ATLAS Thin Gap Chamber Electronics for HL-LHC . . . Tomomi Kawaguchi, on behalf of the ATLAS Muon Collaboration

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Resistive Micromegas for the Muon Spectrometer Upgrade of the ATLAS Experiment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125 Andreas Duedder, on behalf of the ATLAS Muon Collaboration Small-Strip Thin Gap Chambers (sTGC) for the Muon Spectrometer Upgrade of the ATLAS Experiment . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129 Xiao Zhao and Chengguang Zhu Simulation of the ATLAS New Small Wheel (NSW) System . . . . . . . . . 133 Koki Maekawa, on behalf of the ATLAS Muon collaboration Small-Pad Resistive Micromegas for Operation at Very High Rates . . . 138 M. Alviggi, M. Biglietti, M. T. Camerlingo, V. Canale, M. Della Pietra, C. Di Donato, E. Farina, S. Franchino, C. Grieco, P. Iengo, M. Iodice, F. Petrucci, A. Renardi, E. Rossi, G. Sekhniaidze, O. Sidiropoulou, and V. Vecchio

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Readout and Precision Calibration of Square Meter Sized Micromegas Detectors Using the Munich Cosmic Ray Facility . . . . . . . . 143 Andre Zibell and Philipp Lösel Medical Imaging, Security and Other Applications Multi-layer Ionization Chamber for Quality Assurance and Stopping Power Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149 Francis Gagnon-Moisan, Oxana Actis, Zema Chowdhuri, Manuel Dieterle, Michael Eichin, Stefan Koenig, Robert van der Meer, and Damien Charles Weber XEMIS: Liquid Xenon Compton Camera for 3c Imaging . . . . . . . . . . . 154 Y. Xing, M. Abaline, S. Acounis, N. Beaupère, J. L. Beney, J. Bert, S. Bouvier, P. Briend, J. Butterworth, T. Carlier, H. Chanal, M. Cherel, J. P. Cussonneau, M. Dahoumane, L. Gallego-Manzano, D. Giovagnoli, J. Idier, F. Kraeber-Bodéré, P. Le Ray, F. Lefèvre, O. Lemaire, S. Manen, J. Masbou, H. Mathez, E. Morteau, N. Pillet, D. Roy, L. Royer, M. Staempflin, J. S. Stutzmann, R. Vandaele, L. Virone, D. Visvikis, Y. Zhu, and D. Thers Scintillation Signal in XEMIS2, a Liquid Xenon Compton Camera with 3c Imaging Technique . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159 Y. Zhu, M. Abaline, S. Acounis, N. Beaupère, J. L. Beney, J. Bert, S. Bouvier, P. Briend, J. Butterworth, T. Carlier, H. Chanal, M. Cherel, J. P. Cussonneau, M. Dahoumane, L. Gallego-Manzano, D. Giovagnoli, J. Idier, F. Kraeber-Bodere, P. Le Ray, F. Lefèvre, O. Lemaire, S. Manen, J. Masbou, H. Mathez, E. Morteau, N. Pillet, D. Roy, L. Royer, M. Staempflin, J. S. Stutzmann, R. Vandaele, L. Virone, D. Visvikis, Y. Xing, and D. Thers Feasibility Study of a Track-Based Multiple Scattering Tomography . . . . Paul Schütze and Hendrik Jansen

164

Neutrino Detectors Slow Liquid Scintillator for Scintillation and Cherenkov Light Separation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173 Ziyi Guo and Zhe Wang, for the Jinping Neutrino Experiment research group The R&D Progress of the Jinping Neutrino Experiment . . . . . . . . . . . . 178 Lei Guo, On behalf of the Jinping neutrino experiment research group

Contents

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CUPID-0: A Cryogenic Calorimeter with Particle Identification for Double Beta Decay Search . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183 L. Cardani, D. R. Artusa, O. Azzolini, M. T. Barrera, J. W. Beeman, F. Bellini, M. Beretta, M. Biassoni, C. Brofferio, C. Bucci, A. Camacho, L. Canonica, S. Capelli, P. Carniti, N. Casali, L. Cassina, M. Clemenza, O. Cremonesi, A. Cruciani, A. D’Addabbo, I. Dafinei, S. Di Domizio, M. L. di Vacri, F. Ferroni, L. Gironi, A. Giuliani, P. Gorla, C. Gotti, G. Keppel, M. Maino, M. Martinez, S. Morganti, S. Nagorny, M. Nastasi, S. Nisi, C. Nones, F. Orio, D. Orlandi, L. Pagnanini, M. Pallavicini, V. Palmieri, L. Pattavina, M. Pavan, G. Pessina, V. Pettinacci, S. Pirro, S. Pozzi, E. Previtali, A. Puiu, F. Reindl, C. Rusconi, K. Schaeffner, L. Sinkunaite, C. Tomei, M. Vignati, and A. Zolotarova PROSPECT - A Precision Reactor Oscillation and Spectrum Experiment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187 Xianyi Zhang, for the PROSPECT collaboration The KM3NeT Digital Optical Module . . . . . . . . . . . . . . . . . . . . . . . . . . 192 Daniele Vivolo, on behalf of the KM3NeT Collaboration The JUNO Veto Detector System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 197 Haoqi Lu, On behalf of The JUNO Collaboration The CUORE Bolometric Detector for Neutrinoless Double Beta Decay Searches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 202 L. Cassina, C. Alduino, K. Alfonso, D. R. Artusa, F. T. Avignone III, O. Azzolini, G. Bari, F. Bellini, G. Benato, A. Bersani, M. Biassoni, A. Branca, C. Brofferio, C. Bucci, A. Camacho, A. Caminata, L. Canonica, X. G. Cao, S. Capelli, L. Cappelli, L. Cardani, P. Carniti, N. Casali, D. Chiesa, N. Chott, M. Clemenza, S. Copello, C. Cosmelli, O. Cremonesi, R. J. Creswick, J. S. Cushman, A. D’Addabbo, D. D’Aguanno, I. Dafinei, C. J. Davis, S. Dell’Oro, M. M. Deninno, S. Di Domizio, M. L. Di Vacri, A. Drobizhev, D. Q. Fang, M. Faverzani, E. Ferri, F. Ferroni, E. Fiorini, M. A. Franceschi, S. J. Freedman, B. K. Fujikawa, A. Giachero, L. Gironi, A. Giuliani, L. Gladstone, P. Gorla, C. Gotti, T. D. Gutierrez, K. Han, K. M. Heeger, R. Hennings-Yeomans, H. Z. Huang, G. Keppel, Y. G. Kolomensky, A. Leder, C. Ligi, K. E. Lim, Y. G. Ma, M. Maino, L. Marini, M. Martinez, R. H. Maruyama, Y. Mei, N. Moggi, S. Morganti, P. J. Mosteiro, S. S. Nagorny, T. Napolitano, M. Nastasi, C. Nones, E. B. Norman, V. Novati, A. Nucciotti, T. O’Donnell, J. L. Ouellet, C. E. Pagliarone, M. Pallavicini, V. Palmieri, L. Pattavina, M. Pavan, G. Pessina, C. Pira, S. Pirro, S. Pozzi, E. Previtali, C. Rosenfeld, C. Rusconi, M. Sakai, S. Sangiorgio, D. Santone, B. Schmidt, J. Schmidt, N. D. Scielzo, V. Singh, M. Sisti, L. Taffarello, F. Terranova, C. Tomei, M. Vignati, S. L. Wagaarachchi, B. S. Wang, H. W. Wang, B. Welliver, J. Wilson, L. A. Winslow, T. Wise, A. Woodcraft, L. Zanotti, G. Q. Zhang, S. Zimmermann, and S. Zucchelli

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Contents

The NEMO-3 and SuperNEMO Experiments . . . . . . . . . . . . . . . . . . . . 208 Michele Cascella The Study of Rn in the JUNO Prototype Water System . . . . . . . . . . . . 213 Yongpeng Zhang, Cong Guo, Jinchang Liu, Peng Zhang, and ChangGen Yang Photon Detectors Characterisation of Hamamatsu Silicon Photomultiplier Arrays for the LHCb Scintillating Fibre Tracker Upgrade . . . . . . . . . . . . . . . . 221 Axel Kuonen, Guido Haefeli, Olivier Girard, and Maria Elena Stramaglia A New Design for Secondary Electron Measurement and Application . . . Jinhai Li, Shulin Liu, and Baojun Yan

225

The Status of the Batch Test of 20 inch MCP-PMT . . . . . . . . . . . . . . . . 233 Feng Gao, Sen Qian, Zhe Ning, Yinghong Zhang, Guorui Huang, Dong Li, Ling Ren, Shulin Liu, Jianning Sun, and Shuguang Si, on behalf of the MCP-PMT workgroup Results from Pilot Run for MEG II Positron Timing Counter . . . . . . . . 237 M. Nakao, A. De Bari, M. Biasotti, G. Boca, P. W. Cattaneo, M. Francesconi, M. De Gerone, L. Galli, F. Gatti, A. Mtchedilishvili, D. Nicoló, M. Nishimura, W. Ootani, S. Ritt, M. Rossella, M. Simonetta, Y. Uchiyama, and M. Usami Development of Superconducting Tunnel Junction Photon Detectors with Cryogenic Preamplifier for COBAND Experiment . . . . . . . . . . . . . 242 S. H. Kim, Y. Takeuchi, K. Takemasa, K. Nagata, K. Kasahara, S. Yagi, R. Wakasa, R. Senzaki, K. Moriuchi, C. Asano, H. Ikeda, T. Wada, K. Nagase, S. Baba, H. Ishino, A. Kibayashi, S. Matsuura, K. Kiuchi, S. Mima, T. Yoshida, M. Sakai, T. Nakamura, Y. Kato, M. Hazumi, Y. Arai, I. Kurachi, M. Ohkubo, M. Ukibe, S. Shiki, G. Fujii, S. Kawahito, E. Ramberg, M. Kozlovsky, P. Rubinov, D. Sergatskov, J. Yoo, and S. B. Kim Determining the Photon Yield of the LHCb RICH Upgrade Photo-Detection System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 249 M. P. Blago, on behalf of the LHCb RICH Collaboration

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Development of Superconducting Tunnel Junction Detector Using Hafnium for COBAND Experiment . . . . . . . . . . . . . . . . . . . . . . . 254 Kenichi Takemasa, Shinhong Kim, Yuji Takeuchi, Kazuki Nagata, Kota Kasahara, Shunsuke Yagi, Rena Wakasa, Chisa Asano, Youiti Ootuka, Satoru Mima, Kenji Kiuchi, Yasuo Arai, Ikuo Kurachi, Masashi Hazumi, Hirokazu Ishino, Atsuko Kibayashi, Takuo Yoshida, Makoto Sakai, Takahiro Nakamura, Yukihiro Kato, Shuji Matsuura, Shoji Kawahito, Hirokazu Ikeda, Takehiko Wada, Koichi Nagase, Shunsuke Baba, Shigetomo Shiki, Masahiro Ukibe, Go Fujii, Masataka Ohkubo, Erik Ramberg, Mark Kozlovsky, Paul Rubinov, Jonghee Yoo, Domitri A. Sergatskov, and Soo-Bong Kim One to One Preliminary Comparison Between R11410 Photomultiplier Tube and VUV4 Multi-pixel Photon Counter . . . . . . . . 259 F. Arneodo, L. M. Benabderrahmane, V. Conicella, A. Di Giovanni, and O. Fawwaz Application of the SOPHIAS Detector to Synchrotron Radiation X-Ray Experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 263 R. Hashimoto, N. Igarashi, R. Kumai, H. Takagi, S. Kishimoto, T. Kudo, and T. Hatsui Cryogenic Light Detectors for Background Suppression: The CALDER Project . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 267 N. Casali, F. Bellini, L. Cardani, M. G. Castellano, I. Colantoni, C. Cosmelli, A. Cruciani, A. D’Addabbo, S. Di Domizio, M. Martinez, L. Minutolo, C. Tomei, and M. Vignati Improvement of the MCP-PMT Performance Under a High Count Rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 271 Kodai Matsuoka, Shigeki Hirose, Toru Iijima, Kenji Inami, Yuji Kato, Kazuho Kobayashi, Yosuke Maeda, Genta Muroyama, Raita Omori, and Kazuhito Suzuki The Mu2e Calorimeter Photosensors . . . . . . . . . . . . . . . . . . . . . . . . . . . 275 I. Sarra, M. Cordelli, S. Di Falco, E. Diociaiuti, R. Donghia, S. Giovannella, S. Miscetti, L. Morescalchi, G. Pezzullo, F. Spinella, and A. Saputi Electronics Design for the QE Uniformity Test System . . . . . . . . . . . . . 280 Yichao Ma, Xinyang Hong, Sen Qian, Yafan Tao, and Yongsheng Shi Status of the 20-in. PMT Instrumentation for the JUNO Experiment . . . 285 Zhonghua Qin, on behalf of the JUNO collaboration A Quality Control Database System Based on Ionic . . . . . . . . . . . . . . . . 294 Shiyu Yin, Pengyu Chen, Zhe Ning, Sen Qian, Feng Gao, Zhigang Wang, Hao Cai, Yawen Li, Lishuang Ma, Zhile Wang, and Yao Zhu

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New Study for SiPMs Performance in High Electric Field Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 299 Tamer Tolba, on behalf of the nEXO collaboration The Large PMT Quantum Efficiency Test Platform . . . . . . . . . . . . . . . . 304 Feng Gao, Sen Qian, Zhe Ning, Yichao Ma, Zhigang Wang, Na Zhu, Lishuang Ma, Pengyu Chen, Shiyu Yin, Zhile Wang, and Yao Zhu Signal Optimization with HV Divider of MCP-PMT for JUNO . . . . . . . 309 Fengjiao Luo, Zhimin Wang, Zhonghua Qin, Anbo Yang, and Yuekun Heng, On behalf of the JUNO Collaboration Behavior of 144ch HAPDs for the Belle II Aerogel RICH in the Magnetic Field . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 315 K. Ogawa, I. Adachi, R. Dolenec, K. Hataya, H. Kakuno, H. Kawai, H. Kindo, T. Konno, S. Korpar, P. Križan, T. Kumita, M. Machida, M. Mrvar, S. Nishida, K. Noguchi, S. Ogawa, R. Pestotnik, L. Šantelj, T. Sumiyoshi, M. Tabata, M. Yonenaga, M. Yoshizawa, and Y. Yusa Recent Advances in Large Area Micro-channel Plates and LAPPD™ . . . Christopher A. Craven, Bernhard W. Adams, Melvin J. Aviles, Justin L. Bond, Till Cremer, Michael R. Foley, Alexey V. Lyashenko, Michael J. Minot, Mark A. Popecki, Michael E. Stochaj, William A. Worstell, Jeffrey W. Elam, Anil U. Mane, Ed May, Robert G. Wagner, Jingbo Wang, Lei Xia, Junqi Xie, Andrey Elagin, Henry J. Frisch, Camden D. Ertley, Oswald H. W. Siegmund, and Matthew J. Wetstein

319

R&D Studies of New Photosensors for the Hyper-Kamiokande Detector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 325 Alan Cosimo Ruggeri, On behalf of the Hyper-Kamiokande proto-collaboration Semiconductor Detectors Fine-Pixel Detector FPIX Realizing Sub-micron Spatial Resolution Developed Based on FD-SOI Technology . . . . . . . . . . . . . . . . . . . . . . . . 331 Daisuke Sekigawa, Shun Endo, Wataru Aoyagi, Kazuhiko Hara, Shunsuke Honda, Toru Tsuboyama, Miho Yamada, Shun Ono, Manabu Togawa, Yoichi Ikegmi, Yasuo Arai, Ikuo Kurachi, Toshinobu Miyoshi, Junji Haba, and Kazunori Hanagki Secondary Electron Yield of Nano-Thick Aluminum Oxide and its Application on MCP Detector . . . . . . . . . . . . . . . . . . . . . . . . . . . 339 Baojun Yan, Shulin Liu, Kaile Wen, Yuzhen Yang, Tianchi Zhao, Peiliang Wang, and Yuekun Heng

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The CMS Tracker Phase-2 Upgrade for the HL-LHC Era . . . . . . . . . . 344 Axel König, on behalf of the CMS Tracker group Pixel Detector Developments for Tracker Upgrades of the High Luminosity LHC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 349 M. Meschini, M. Boscardin, G. F. Dalla Betta, M. Dinardo, G. Giacomini, D. Menasce, R. Mendicino, A. Messineo, L. Moroni, S. Ronchin, D. M. S. Sultan, L. Uplegger, L. Viliani, I. Zoi, and D. Zuolo Modules and Front-End Electronics Developments for the ATLAS ITk Strips Upgrade . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 356 Carlos García Argos, on behalf of the ATLAS ITk Collaboration Integrated CMOS Sensor Technologies for the CLIC Tracker . . . . . . . 361 Magdalena Munker, on behalf of the CLICdp Collaboration Study of the CMS Phase 1 Pixel Pilot Blade Reconstruction . . . . . . . . . 366 Tamas Almos Vami and Viktor Veszpremi, for the CMS Collaboration A Monolithic Pixel Sensor with Fine Space-Time Resolution Based on Silicon-on-Insulator Technology for the ILC Vertex Detector . . . . . . . . 370 Shun Ono, Miho Yamada, Yasuo Arai, Toru Tsuboyama, Manabu Togawa, Teppei Mori, Ikuo Kurachi, Kazuhiko Hara, Yoichi Ikegami, Daisuke Sekigawa, Shun Endo, and Akimasa Ishikawa Radiation Monitoring with Diamond Sensors for the Belle-II Vertex Detector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 375 Chiara La Licata, on behalf of the BEAST II collaboration Enhanced Lateral Drift Sensors: Concept and Development . . . . . . . . . 380 A. Velyka and H. Jansen Commissioning of the Phase-1 Upgrade of the CMS Pixel Detector . . . . 385 Benedikt Vormwald, for the CMS Tracker Group Progress on the Upstream Tracker Electronics for the LHCb Upgrade . . . 390 Carlos Abellan Beteta Staves and Petals: Multi-module Local Support Structures of the ATLAS ITk Strips Upgrade . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 395 Daniel Rodríguez Rodríguez and Carlos García Argos, behalf of the ATLAS ITk Collaboration Tracking and Vertexing with the ATLAS Inner Detector in the LHC Run-2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 400 KyungEon Choi, on behalf of the ATLAS collaboration Capacitively Coupled Pixel Detectors: From Design Simulations to Test Beam . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 404 Mateus Vicente Barreto Pinto

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Analysis and Simulation of HV-CMOS Assemblies for the CLIC Vertex Detector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 409 M. Buckland, on behalf of the CLICdp collaboration Belle II Silicon Vertex Detector (SVD) . . . . . . . . . . . . . . . . . . . . . . . . . . 414 S. Bahinipati, K. Adamczyk, H. Aihara, C. Angelini, T. Aziz, V. Babu, S. Bacher, E. Barberio, Ti. Baroncelli, To. Baroncelli, A. K. Basith, G. Batignani, A. Bauer, P. K. Behera, T. Bergauer, S. Bettarini, B. Bhuyan, T. Bilka, F. Bosi, L. Bosisio, A. Bozek, F. Buchsteiner, L. Bulla, G. Casarosa, M. Ceccanti, D. Červenkov, S. R. Chendvankar, N. Dash, G. De Pietro, S. T. Divekar, Z. Doležal, D. Dutta, F. Forti, M. Friedl, B. Gobbo, K. Hara, T. Higuchi, T. Horiguchi, C. Irmler, A. Ishikawa, H. B. Jeon, C. Joo, J. Kandra, N. Kambara, K. H. Kang, T. Kawasaki, P. Kodyš, T. Kohriki, S. Koike, M. M. Kolwalkar, I. Komarov, R. Kumar, W. Kun, P. Kvasnička, L. Lanceri, J. Lettenbicher, J. Libby, S. C. Lee, T. Lueck, M. Maki, P. Mammini, A. Martini, S. N. Mayekar, G. B. Mohanty, S. Mohanty, T. Morii, K. R. Nakamura, Z. Natkaniec, Y. Onuki, W. Ostrowicz, A. Paladino, E. Paoloni, H. Park, F. Pilo, A. Profeti, I. Rashevskaya, K. K. Rao, G. Rizzo, P. K. Resmi, M. Rozanska, J. Sasaki, N. Sato, S. Schultschik, C. Schwanda, Y. Seino, N. Shimizu, J. Stypula, J. Suzuki, S. Tanaka, G. N. Taylor, R. Thalmeier, R. Thomas, T. Tsuboyama, S. Uozumi, P. Urquijo, L. Vitale, S. Watanuki, M. Watanabe, I. J. Watson, J. Webb, J. Wiechczynski, S. Williams, B. Würkner, H. Yamamoto, H. Yin, T. Yoshinobu, and L. Zani, Belle-II SVD Collaboration Radiation Hardness of Small-Pitch 3D Pixel Sensors up to HL-LHC Fluences . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 421 J. Lange, S. Grinstein, M. Manna, G. Pellegrini, D. Quirion, S. Terzo, and D. Vázquez Furelos CMOS Pixel Development for the ATLAS Experiment at HL-LHC . . . 426 B. Ristic, on behalf of the ATLAS Collaboration Author Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 431

Calorimeters

High Granularity Digital Si-W Electromagnetic Calorimeter for Forward Direct Photon Measurements at LHC Hongkai Wang(B) for the ALICE-FoCal Collabration Institute for Subatomic Physics, Utrecht University, P.O.B. 80000, 3508 Utrecht, TA, The Netherlands [email protected]

Abstract. A compact digital Si-W sampling electromagnetic calorimeter prototype using Monolithic Active Pixel Sensors (MAPS) with a granularity of 30×30 µm and a total depth of 28 X0 has been built and tested with beams. The test beam results demonstrate not only good energy linearity and reasonable energy resolution, but also a position resolution of better than 30 µm. This precise position determination and the detailed knowledge of the electromagnetic shower shape obtained will provide the crucial capability for two-photon separation for the final design.

1

Introduction

It is widely expected that the non-linear growth of parton densities at low x predicted from linear QCD evolution will lead to gluon saturation. As a decisive probe of gluon saturation, the measurement of forward (3.5 < y < 5.3) direct photons in a new region of low x (10−5 ∼ 10−6 ) in proton-nucleus collisions at the LHC is proposed [1]. The Forward Calorimeter (FoCal) is proposed as a detector upgrade to the ALICE experiment to discriminate direct photons from decay photons with very small opening angle from neutral pions. 1.1

Prototype Design

A compact EM calorimeter prototype using Monolithic Active Pixel Sensors (MAPS) with a granularity of 30 × 30 µm has been built in Utrecht University. The prototype consists of 24 layers. Every layer consists of a tungsten absorber, silicon sensor, printed circuit board and glue. The radiation thickness of every layer is 0.97 X0 . Between layers 21 and 22, 6.7 X0 of tungsten are placed to increase the total depth of 28 X0 [2]. The MIMOSA-23 [3] sensor has been chosen as sensitive detector and each sensor contains 640 × 640 pixels. A full layer consists of two identical modules, each with two sensors, mounted in alternating orientations, with the sensors covering opposite halves of the detector and facing each other (Fig. 1). The active area of a layer is around 4 × 4 cm2 , c Springer Nature Singapore Pte Ltd. 2018  Z.-A. Liu (Ed.): TIPP 2017, SPPHY 213, pp. 3–6, 2018. https://doi.org/10.1007/978-981-13-1316-5_1

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composed of four sensors. This design leads to a narrow gap between sensors along the x direction and an overlap along the y direction. Except for layer 0, the detector was tuned to a fake hit rate of 10−5 , after masking the pixels, channels, or sensors which are always active, to get the appropriate sensitivities. In order to enhance the efficiency of layer 0, it was tuned to 10−4 for some of the data sets (30, 50, 100 GeV) [3].

Fig. 1. FoCal Si-W EMCal prototype, (left) the stack and (right) view of a full layer.

2

Event Reconstruction

The total 39M pixels are able to provide unprecedented detail of particle trajectory information in the detector. Minimum Ionizing Particles (MIP) can be tracked by fitting with a straight line.

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Fig. 2. Shower center determination procedure: (left) summed response of all working layers and (right) summed response with a cut on the W0 = 3 hits in a pixel region.

The extremely high granularity of the prototype also allows precise shower position reconstruction by using the information of all working layers with the following equation  t w xi where ωi = max {0, Ai − W0 } (1) xc = i i t i wi

High Granularity Digital Si-W Electromagnetic Calorimeter

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Here Ai is the amplitude in the pixel region i when superimposing all working layers, W0 is the minimum number of hits that is required for a pixel area to be included in the calculation (see Fig. 2). W0 and t are optimized for different energies.

3

Corrections and Event Selection

In order to obtain a good spatial resolution, the alignment of the detector elements in the transverse plane has been measure with cosmic muons, which have a wide angular range and thus cover the full detector. The precision of the alignment is better than the pixel size. It was found that the test beam had a slight inclination with respect to the detector. The values of inclination angle of the beam can be obtained by calculating the length projection of reconstructed pion tracks. A two-step calibration procedure was established [3]. There are two intermediate steps for correcting the relative response of the sensors – Equalize the sensitivities of sensors with a layer by using hit density profiles. – Use the Gamma distribution to calibrate the layer by layer response.

Table 1. Overview of the different data samples collected in test beams. Time

Site

Particle type Energy (GeV)

Feb 2014 DESY e+ ±

2, 3, 4, 5.4 +

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Nov 2014 CERN π , e , (e ) 30, 50, 100, (244)

The prototype has been tested with different types of beam at various energies. Table 1 presents an overview of the different data sets. Electron event selection is based on the following criteria: – The impact position of incoming particle was selected, requiring that the electron shower center can be reconstructed and also cluster can be found in layer 0. The gap and overlap region were excluded from this step. – A cut on the number of hits was set to reject the pion contamination. The estimate of pion contamination for all energies is negligible (∼1%).

4

Results and Conclusion

Figure 3 shows the calibrated energy response of the prototype. The left panel shows a fit to characterize the linearity. Simulations are shown for comparison. The right panel shows the energy resolution, also compared to simulation results with an ideal detector as well as the “real detector” where the non-functioning

σE / E (%)

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Fig. 4. (Left) Precision of reconstructed shower center by using Eq. 1 (W0 = 3, t = 2 and σ = 27 µm). (Right) Lateral profile of 100 GeV electron data.

sensors are taken into account. The energy resolution can be characterised as σ 0.29 √ ⊕ 0.063 , which is good enough for a forward detector. E = 0.028 ⊕ E E The extremely high granularity provides excellent shower position resolutions, as demonstrated in Fig. 4 left, which the distribution of the residual between the cluster in layer 0 and the reconstructed shower position for 244 GeV electrons. The right panel shows lateral hit density profiles in selected layers for a 100 GeV electrons. The high spatial resolution of the detector provides unprecedented precision for this measurement will be crucial for two-photon separation at short distances in the final design.

References 1. Peitzmann, T.: Proceedings of CHEF 2013. arXiv:1308.2585v1 2. Nooren, G.: Extremely fine grained electro-magnetic calorimeter, PoS, 026 (RD11) 3. Zhang, C.: Nucl. Instr. Meth. Phys. Res. A 845, 542–547 (2017)

The CMS High-Granularity Calorimeter for Operation at the High-Luminosity LHC Florian Pitters1,2(B) On behalf of the CMS collaboration 1

2

CERN, Geneva, Switzerland [email protected] Vienna University of Technology, Vienna, Austria

Abstract. The High Luminosity LHC (HL-LHC) will integrate 10 times more luminosity than the LHC, posing significant challenges for radiation tolerance and event pileup on detectors, especially for forward calorimetry, and hallmarks the issue for future colliders. As part of its HL-LHC upgrade program, the CMS collaboration is designing a High Granularity Calorimeter to replace the existing endcap calorimeters. It features unprecedented transverse and longitudinal segmentation for both electromagnetic (ECAL) and hadronic (HCAL) compartments. This will facilitate particle-flow calorimetry, where the fine structure of showers can be measured and used to enhance pileup rejection and particle identification, whilst still achieving good energy resolution. The ECAL and a large fraction of HCAL will be based on hexagonal silicon sensors of 0.5 to 1 cm2 cell size, with the remainder of the HCAL based on highlysegmented scintillators with SiPM readout. The intrinsic high-precision timing capabilities of the silicon sensors will add an extra dimension to event reconstruction, especially in terms of pileup rejection. An overview of the HGCAL project is presented, covering motivation, engineering design, readout and trigger concepts, and expected performance. Keywords: CMS · HGCAL · Calorimeters High granularity · Particle flow

1

· Silicon pad detectors

Introduction

Starting from 2026 onwards, the HL-LHCs instantaneous luminosity will be increased by a factor 5 to 7 compared to LHC and will result in up to 200 collisions per bunch crossing. In this mode, LHC will run for 10 years and deliver an integrated luminosity of about 3000 fb−1 . The current CMS detector was designed for operation at 25 collisions per bunch crossing and up to 500 fb−1 [1]. To cope with the new environment and retain a good physics performance up to 3000 fb−1 , several upgrades to the CMS subdetectors are planned [2]. The endcap calorimeters are among the subdetectors that will be most exposed to c Springer Nature Singapore Pte Ltd. 2018  Z.-A. Liu (Ed.): TIPP 2017, SPPHY 213, pp. 7–11, 2018. https://doi.org/10.1007/978-981-13-1316-5_2

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high radiation levels. Figure 1 shows the expected total dose and hadron fluences as a function of R and Z. In the innermost regions, the detector has to withstand 1016 neq/cm2 and 150 MRad. Under these conditions, the current endcap calorimeters would degrade very quickly in performance [2]. Therefore, they will be completely replaced by a silicon and scintillator based highly granular sampling calorimeter called HGCAL (High Granularity Calorimeter).

(a)

(b)

Fig. 1. The expected integrated hadron fluences for the endcap expressed in 1 MeV neutron equivalent per cm2 are shown in (a) and the total integrated dose in (b). The flux and dose are varying with R and Z, allowing for different technology choices depending on the exact location. The electromagnetic part of HGCAL will use silicon as active medium while the hadronic part will use silicon in the innermost regions and scintillating tiles with SiPM readout for the outer parts. Figures first printed in Reference [2]. Published with permission by CERN.

2

Detector Design

The CMS HGCAL consist of an electromagnetic part called EE and two hadronic parts called FH & BH.1 The electromagnetic part will be 25 X0 deep and will consists of 28 layers of silicon pad sensors as active elements with lead in a stainless steel envelope as absorber. The two hadronic parts are in total 8.5 λI deep with 24 layers and steel absorbers. As active elements, silicon will be used in the high |η| regions and scintillating tiles with SiPM readout in the lower |η| regions. The full system will be maintained at −30 ◦ C using evaporative CO2 cooling to limit the leakage current of the silicon sensors. With silicon pads and scintillating tiles, high granularity in transverse and longitudinal direction will be maintained throughout the calorimeter and will allow for particle flow analysis. High precision time measurement with better than 50 ps resolution on a cell level is aspired for vertex reconstruction and pile-up rejection. 1

EE stands for “Endcap Electromagnetic” calorimeter, FH for “Front Hadronic” calorimeter and BH for “Back Hadronic” calorimeter.

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Active Elements

One of the most relevant quantity for the detector performance is the signal-tonoise ratio. For silicon, it has been shown that the signal loss due to irradiation is decreased in thinner sensors and when operating at increased bias voltages [2,3]. The increased noise contribution from the leakage current can be mitigated by cooling. Both aspects are displayed in Fig. 2. Additionally, the intrinsic time resolution of silicon has been shown to be below 15 ps for signals above 20 MIPs [3]. In total, the system will consist of roughly 600 m2 of silicon. The use of 6 or 8 in. wafers with hexagonal geometry is foreseen to reduce costs. The active thickness will be adapted to the expected radiation dose and will vary between 120, 200 and 300 µm.2 The cell capacitance should be around 50 pF for all sensor thicknesses and therefore thinner sensors will be equipped with smaller cells. A granularity of 0.5 cm2 for the 120 µm and 1 cm2 for 200 and 300 µm thick sensors will be used. One of the key aspects of these sensors is the high-voltage sustainability to mitigate radiation damage. The goal is a breakdown voltage above 1 kV. It is also foreseen to use a few cells with smaller area than the regular ones on each sensor. The smaller area at unchanged thickness will reduce the noise contributions from capacitance and leakage current in these cells, so that they should still be sensitive to single MIPs after 3000 fb−1 .

Fig. 2. The mean signal in silicon diodes for different neutron fluences can be seen in (a). Thinner sensors and operation at higher voltages mitigate the signal loss. The scaling of leakage current with active detector volume and neutron fluence is shown in (b). The noise contribution scales with the square root of the leakage current. Figures first printed in Reference [2]. Published with permission by CERN.

At larger distances to the interaction point radiation levels are lower and plastic scintillating tiles with SiPM readout will be used, analogous to the CALICE AHCAL [4]. The exact intersection between scintillator and silicon regions as well as the tile granularity will be evaluated in the coming months. 2

Whether the active thickness is best reached via deep diffusion, physical thinning or an epitaxial layer is currently under study.

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Modules, Absorbers and Mechanical Integration

Silicon modules start with a metallic baseplate (CuW in EE and Cu in FH/BH), which acts as an absorber and mechanical support, that has a polyimide goldplated foil glued to it. The silicon sensor is then glued onto that foil. The readout PCB hosting the front-end ASICs is in turn glued onto the sensor and wirebonds reaching through holes in the PCB connect to the sensor contact pads. The design of the active scintillator modules is currently being developed. Modules will be mounted on cooling plates together with the front-end electronics to make up cassettes. The absorber structure that hosts the cassettes will be made in full disks to guarantee an optimal physics performance. In the EE case, self-supporting double sided cassettes are used while in the FH and BH case, the mixed cassettes will be directly mounted on the steel absorber. 2.3

Readout Electronics

The driving requirements for the front-end readout ASIC are a large dynamic range of 0.4 fC to 10 pC (15 bits), a noise level below 2000 electrons, timing information with below 50 ps accuracy and radiation hardness up to 150 MRad. The goal is to keep within a power budget of around 10 mW/channel for the analog part. To meet these requirements, a chip based on OMEGA’s ROC family [5] is being developed. The baseline option includes two traditional gain stages and a time-over-threshold stage, as well as a time-of-arrival path with 50 ps binning. The ASIC will be fabricated in TSMC 130 nm CMOS technology which has been qualified up to 400 MRad [2]. Information from HGCAL will also be used for the L1 trigger decision. A subset of the data is sent to a concentrator chip and, after clustering, combined with the track trigger. The trigger latency of 12.5 µs drives the requirement for large buffer sizes in the readout chip. A first version of the readout chip will be submitted in the summer of 2017.

3

Expected Performance

The choice of lead as absorber with a small Moliere radius and a large ratio of interaction length to radiation length allows for a compact calorimeter with excellent particle separation capabilities. The narrow showers together with the high granularity and excellent time resolution will allow for a pile-up suppression in the first few layers of EE. The intrinsic energy resolution of the√EE part for incident electrons is expected to have a stochastic term below 25%/ GeV and a constant term below 1% [2]. These values are sufficient as the energy resolution will be dominated by the confusion term in the particle flow algorithm rather than the intrinsic resolution of the calorimeter. Optimisation of these algorithms to the physics environment and detector design is currently ongoing.

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11

Outlook

The CMS collaboration is making good progress towards the construction of a new generation of imaging calorimeter. The basic design has been validated in testbeam and design optimisation is ongoing. The technical design report is expected to be released by the end of 2017.

References 1. The CMS Collaboration: The CMS experiment at the CERN LHC. J. Instrum. 3(08), S08004 (2008). http://stacks.iop.org/1748-0221/3/i=08/a=S08004 2. Contardo, D., Klute, M., Mans, J., Silvestris, L., Butler, J.: Technical proposal for the phase-II upgrade of the CMS detector. Technical report, CERN-LHCC2015-010. LHCC-P-008. CMS-TDR-15-02, Geneva, June 2015. https://cds.cern.ch/ record/2020886 3. Curras, E., et al.: Radiation hardness and precision timing study of silicon detectors for the CMS high granularity calorimeter (HGC). Nucl. Instr. Meth. Phys. Res. A 845, 60–63 (2017). http://www.sciencedirect.com/science/article/pii/ S0168900216303679. proceedings of the Vienna Conference on Instrumentation 2016 4. The CALICE Collaboration: Construction and commissioning of the CALICE analog hadron calorimeter prototype. J. Instrum. 5(05), P05004 (2010). http://stacks. iop.org/1748-0221/5/i=05/a=P05004 5. Borg, J., et al.: Skiroc2CMS an ASIC for testing CMS HGCAL. J. Instrum. 12(02), C02019 (2017). http://stacks.iop.org/1748-0221/12/i=02/a=C02019

Performance Study for the CEPC ScW ECAL Hang Zhao1,2, Zhi-gang Wang1(&), Peng Hu1,2, Tao Hu1, Sen Qian1, Ming-hui Li3, and Li-shuang Ma4

2

1 StateKey Laboratory of Particle Detection and Electronics, Institute of High Energy Physics, CAS, Beijing 100049, China [email protected] University of Chinese Academy of Sciences, Beijing 100049, China 3 Tianjin Polytechnic University, Tianjin 300387, China 4 North China University of Technology, Beijing 100144, China

Abstract. The Circular Electron Positron Collider (CEPC) project is a Higgs/Z factory proposed by Chinese high energy physics community. A fine granular scintillator-tungsten electromagnetic calorimeter (ScW ECAL) is under development for the application of the particle flow algorithm (PFA) at CEPC. The active layers of the ScW ECAL are consisting of 5
45 mm2 plastic scintillator strips, with silicon photomultiplier (SiPM) readout. A set of ScW ECAL geometries has been implemented into the Geant4 simulation to optimize the geometry parameters such as layer numbers and scintillator sensor thickness. The performances of SiPM and the scintillator strip detector were tested, and the test results indicate that the SiPM and the sensor detector worked well. These results are meaningful for the construction and the tests of the prototype at the next stage. Keywords: CEPC

 ECAL  Scintillator  SiPM

1 Introduction The CEPC [1] project, which is proposed by Chinese high energy physics community, is preliminarily designed as a Higgs/Z factory to boost the precision of Higgs properties and SM measurements. By using PFAs [2], together with a detector system that is optimized for the PFAs’ application, a full spectrum of physics objects can be reconstructed with great efficiency and precision for the physics program at CEPC. The PFA requires calorimeters having the capability of separation from individual particles in jets, and consequently requires fine-segmented calorimeters. With the recent development of SiPM, the plastic scintillator technique can provide such a small and feasible unit of detectors. A fine granular scintillator-tungsten ECAL, which consists of plastic scintillator detector as active sensor and tungsten plate as absorber, is considered by CEPC collaboration. The plastic scintillator is designed as strip shape and aligned orthogonally in adjacent layers to provide effective granularity close to the strip width while the number of channels can be reduced by an order of magnitude. In this paper, we describe the results of ScW ECAL performance study with Geant4 [3] simulation and sensor detector test. In Sect. 2, the Geant4 simulation results of the © Springer Nature Singapore Pte Ltd. 2018 Z.-A. Liu (Ed.): TIPP 2017, SPPHY 213, pp. 12–16, 2018. https://doi.org/10.1007/978-981-13-1316-5_3

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photon intrinsic energy resolution with different layer number and scintillator sensor thickness are compared. In Sect. 3, the performance of the SiPM is shown. And the test result of scintillator strip sensor is shown in Sect. 4.

2 Simulation of Geometry Parameter Using simulated single photon samples, the intrinsic photon energy resolutions at different ECAL layer number and scintillator sensor thickness were studied. When changing the layer number in ScW ECAL simulation, the total thickness of absorber layers should remain the same to maintain the leakage of electromagnetic showers. Figure 1 shows the intrinsic photon energy resolution when the layer number is 30, 25, and 20, while the total thickness of absorber is 84 mm and the thickness of scintillator sensor in each layer is 2 mm. The energy resolution gets worse if the layer number was reduced, because of the lower sampling ratio.

Fig. 1. Photon energy resolution when the layer number is 30, 25, and 20, while the total thickness of absorber is 84 mm and the thickness of scintillator sensor in each layer is 2 mm.

Figure 2 shows the photon energy resolution with 1 mm, 2 mm, and 3 mm thick scintillator sensor in each of the 30 layers, while the thickness of tungsten plates remains 2.8 mm. As expected, the energy resolution becomes better with the thicker sensor.

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Fig. 2. Photon energy resolution with 1 mm, 2 mm, and 3 mm thick scintillator sensor in each of the 30 layers.

3 SiPM Performance Study The SiPM is a novel semiconducting photon counting device manufactured by Hamamatsu Photonics K.K. [4]. As the pulse spectra shown in Fig. 3, the individual peaks are clearly separated from each other, which proves excellent photon counting ability of the SiPM.

Fig. 3. Spectra of the SiPM signal.

Because each pixel on a SiPM can only detect one photon at once and a few nanoseconds are needed before recovery, the SiPM is not a linear photon detection device, especially when the input light intensity is strong. The application of CEPC ScW ECAL is a challenge to the dynamic range of SiPM, and the study of the response

Performance Study for the CEPC ScW ECAL

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is necessary. For a short time light pulse, the response of the SiPM can be theoretically calculated as Nfired ¼ Npixel ð1  eNpe =Npixel Þ

ð1Þ

However, for the ScW ECAL, the width of the light pulse should not be ignored, and some pixels of SiPM can detect more than one photon in an event. The response of the SiPM should be modified as Nfired ¼ Neff ð1  eNpe =Neff Þ

ð2Þ

The Neff stands for the effective number of pixels on a SiPM, which is relative to the width of the input light pulse. A dynamic range test result with 1600-pixel SiPM is shown in Fig. 4. Further tests are needed for the SiPM with more pixels.

Fig. 4. The response curve of 1600-pixel SiPM. The black points are test results; the red curve is the fit result with Eq. (2); the blue line is the ideal linear result.

4 Scintillator Strip Test Because the SiPM is coupled at one end of the scintillator strip, the signal readout by SiPM will not be homogeneous, which will affect the performance of the ScW ECAL. Figure 5 shows the test result of the light pulse height readout by the SiPM when the b ray from a Sr90 source hit at different positions of the scintillator strip. The result shows that the non-homogeneity of the scintillator detector is 23%.

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Fig. 5. Light pulse height readout by the SiPM for ScW ECAL sensor detector.

5 Summary and Plan In this paper, we show the results of the performance study of the ScW ECAL, including the simulation results at different geometry parameters and the performance test results of the SiPM and the scintillator strip sensor. The optimization and performance study will be carried on more deeply. A prototype of ScW ECAL is also planned to be constructed and tested. Acknowledgements. This research programme has been partially supported by National Key Programme for S&T Research and Development (Grant NO. 2016YFA0400400), the CEPC Innovative project of IHEP, the National Natural Science Foundation of China (Grant NO. 11675196, NO. 11175198, NO. 11475209 and NO. 11675205), and the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant NO. XDA10010400).

References 1. CEPC Homepage. http://cepc.ihep.ac.cn/index.html 2. Thomson, M.: Particle flow calorimetry and the PandoraPFA algorithm. Nucl. Instrum. Methods A 611, 25–40 (2009). arXiv:0907.3577 [physics.ins-det] 3. The GEANT4 Collaboration, Agostinelli, S., et al.: GEANT4: a simulation toolkit. Nucl. Instrum. Methods A 506, 250–303 (2003) 4. Hamamatsu Photonics K.K. Homepage. http://www.hamamatsu.com/index.html

Development of ATLAS Liquid Argon Calorimeter Readout Electronics for the HL-LHC Maximilian Hils(B) On behalf of the ATLAS Liquid Argon Calorimeter Group Institut f¨ ur Kern und Teilchenphysik, Technische Universit¨ at Dresden, Dresden, Germany [email protected]

Abstract. The ATLAS Liquid Argon (LAr) Calorimeter was developed and constructed to measure proton-proton collisions at the Large Hadron Collider (LHC) with a design luminosity of 1034 cm−2 s−1 which is already exceeded. For 2026, the start of the High Luminosity LHC (HL-LHC) is planned, which will deliver 5 to 7 times the design luminosity. Therefore, a replacement of the readout electronics is required. Results of the research and development (R&D) of preamplifier and analog-to-digital converter for the new electronics are presented.

1

Introduction

For 2026, the start of the HL-LHC is planned with an instantaneous luminosity of up to 7 × 1034 cm−2 s−1 . In order to cope various difficulties, an upgrade of the ATLAS [1] detector will take place from 2024 till 2026. The higher luminosity conditions of the HL-LHC will exceed the design parameters of the LAr readout electronics. Especially, the rise in the mean number of interactions in the proton-proton collisions will pose a huge challenge to the trigger system. The trigger system will be required to have a hardware trigger rate of up to 4 MHz and a data buffer of up to 30 µs. The currently installed front-end boards (FEBs) are not able to provide these numbers. Therefore, the 1524 FEBs as well as the back-end electronics need to be replaced.

2

Upgrade of the Readout Electronics

The readout electronics of the LAr are separated in the front-end and the backend part. The front-end electronics are installed on the detector and will consist of the FEBs and the LAr Trigger Digitizer Boards (LTDBs). The back-end electronics are located off-detector in a radiation-shielded cavern and will comprise the LAr Signal Processors (LASPs) and the LAr Digital Processing System c Springer Nature Singapore Pte Ltd. 2018  Z.-A. Liu (Ed.): TIPP 2017, SPPHY 213, pp. 17–21, 2018. https://doi.org/10.1007/978-981-13-1316-5_4

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(LDPS). During the phase-1 upgrade [2] from 2019 till 2020, the LTDBs and LDPS will be installed. The phase-2 upgrade [3] of the readout electronics forsees a replacement of the FEBs and the installation of the new LASPs.

3

Requirements for the Front-End Electronics

The lower range of the preamplifiers of the FEBs is determined by the noise level and the amplitude of the minimum ionizing particle signal, while the upper end is defined by the maximum deposited energy in a single cell that is expected from new physics or Standard Model (SM) processes. Also, the high-precision measurements require an excellent linearity of the electronics being around 1 per mille for energies up to about 10% of the dynamic range. The noise level of the analog-to-digital converters (ADCs) should be below the intrinsic calorimeter resolution. Therefore either two gains with 14-bit ADCs or three gains with 12-bit ADCs are required to cover the 16-bit dynamic range (cf. Fig. 1).

Fig. 1. Intrinsic calorimeter resolution (black) and resolution of a two gain (14-bit ADCs, red) and a three gain (12-bit ADCs, blue) solution.

3.1

Preamplifier

The preamplifier will be implemented in a single application-specific integrated circuit (ASIC) together with the shaper. A low noise level and a low power consumption are required.

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There are two different R&D paths ongoing. One being a 65 nm complementary metal-oxide-semiconductor (CMOS) for which the test chips were submitted in April 2017 and a 130 nm CMOS for which the test chips were submitted September 2016. The 65 nm chip is a fully differential preamplifier. Post-layout simulations agree well with the schematics (cf. Fig. 2). The 130 nm CMOS is an electronically cooled preamplifier. The first measurements (cf. Fig. 3) show that the desired linearity of about 1 per mille for 10% of the dynamic range is achievable. In general, there is a good agreement with the simulations for the 130 nm design. Only the equivalent noise input shows a dicrepancy. However, the issue is understood and there will be a new prototype in 2017.

Fig. 2. Post layout simulations of the 65 nm CMOS.

3.2

Fig. 3. First measurements of linearity of the 130 nm CMOS.

Analog-to-Digital Converter

For the ADC, commercial and custom solutions are under investigation. An important criterion for choosing the ADC is the compatibility to the CERN lpGBT (low power gigabit transceiver) [4]. The custom design in 65 nm is a 14-bit ADC based on a 12-bit successive approximation register (SAR) ADC and a dynamic range enhancer (DRE). Monte Carlo simulations of capacitor mismatches (cf. Fig. 4) give an effective number of bits of about 11.75-bits. As for the commercial solutions, twenty 14-bit and seven 16-bit ADCs were reviewed. Based on performance and cost, a subset of these ADC candidates were selected for first irradiation tests scheduled for this year.

4

Specifications for the Back-End Electronics

After the phase-2 upgrade, there will be about 35000 optical fiber connections from the front-end electronics to the back-end. The input data rate will be about 275 Tbps. For the digital signal processing, 400 high-performance fieldprogrammable gate arrays (FPGAs) are required.

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Fig. 4. Monte Carlo simulation of the capacitor mismatches for the 65 nm custom ADC.

5

ATLAS Readout Electronics Upgrade Simulation

In addition to the hardware R&D, a simulation tool ATLAS Readout Electronics Upgrade Simulation (AREUS) was developed to simulate the readout chain. AREUS is used to study different filter algorithms for the digital signal processing. It is highly configurable. For instance, ADC settings, electronics noise, pile-up conditions, and pulse shapes can be switched easily. Acknowledgments. This work was supported in part by the German Bundesministerium f¨ ur Bildung und Forschung (BMBF) within the research network FSP-103.

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References 1. ATLAS Collaboration, The ATLAS Experiment at the CERN Large Hadron Collider, JINST 3, S08003 (2008) 2. ATLAS Collaboration, ATLAS Liquid Argon Calorimeter Phase-I Upgrade Technical Design Report, CERN-LHCC-2013-017 3. ATLAS Collaboration, ATLAS Phase-II Upgrade Scoping Document, CERNLHCC-2015-020 4. https://espace.cern.ch/GBT-Project/default.aspx. Accessed 15 June 2017

Upgrade of the ATLAS Tile Calorimeter for the High Luminosity LHC F. Tang(&) on behalf of the ATLAS Tile Calorimeter System The University of Chicago, Chicago, IL 60637, USA [email protected]

Abstract. The ATLAS hadronic Tile Calorimeter (TileCal) covers the central angular region of the detector. The TileCal will undergo a major replacement of its on- and off-detector electronics in 2024 for the high luminosity program of the LHC. The TileCal signals will be digitized and sent directly to the offdetector electronics, which will store them in fixed-latency buffers and digitally construct and transmit trigger sums for the Level-1 trigger at a rate of 40 MHz. The improved signal resolution and precision will allow more complex and effective algorithms to be implemented in the Level-1 trigger hardware. Three different front-end options are currently being investigated for the TileCal upgrade with extensive test beam studies to determine which option will be selected. The off-detector electronics are based on the Advanced Telecommunications Computing Architecture (ATCA) standard and are equipped with large, modern FPGAs and high-performance optical links. The on-detector electronics are designed to operate in a high radiation environment and has a high level of redundancy. The large scale, high performance FPGAs are also extensively used for the logic functions and data links in data acquisition for ondetector electronics. A hybrid Demonstrator prototype with the new calorimeter module electronics, but still compatible with the present system, is planned to be inserted in ATLAS in one of the next winter shutdowns. We present the components of the Tile Calorimeter upgrade for the high luminosity LHC, the production and performance of the readout electronics prototypes, the results of the beam tests at CERN and the plans for the next years. Keywords: LHC ATCA


HL-LHC
Tile calorimeter
Analog front-end readout

1 Introduction The High Luminosity Large Hadron Collider (HL-LHC, also known as Phase-2) is expected to start in 2026, with upgrade of the luminosity of up to 5–7  1034 cm−2 s−1 [1], allowing us to explore physics beyond the Standard Model, to study the electroweak symmetry breaking mechanism, and to measure the Higgs boson in detail. Here we describe the ATLAS TileCal upgrade program for the HL-LHC. The ATLAS TileCal is a cylindrical hadronic sampling detector with steel absorbers and scintillating plastic tiles, surrounding the EM calorimeter cryostat. It is divided into one long central © Springer Nature Singapore Pte Ltd. 2018 Z.-A. Liu (Ed.): TIPP 2017, SPPHY 213, pp. 22–30, 2018. https://doi.org/10.1007/978-981-13-1316-5_5

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barrel (LB) of 5.56 m in length, covering a total pseudorapidity range |η| < 1.0, and two extended barrel (EB) cylinders of 2.91 m in length, covering in total a pseudorapidity range of 0.8 < |η| < 1.7. Each cylinder is composed of 64 detector modules, each module covers the azimuthal u in an angle of 2p/64. The TileCal and its readout electronics contained in the Tile Electronics Drawers are depicted in Fig. 1.

Fig. 1. TileCal architecture with the readout system in the Tile Electronics Drawers Copyright 2017 CERN for the benefit of the ATLAS Collaboration. CC-BY-4.0 license

2 On-detector Electronics The TileCal on-detector electronics read out a total of *10, 000 photomultiplier tubes (PMT), housed in 256 Tile Electronics Drawers; the system structure is shown in Fig. 2. A Tile Electronics Drawer will consist of up to 4 identical Mini-drawers supporting up to 12 PMT blocks each, with front-end readout electronics and a Main Board (MB) to handle the data digitization and data concentration, and a Daughter Board (DB) to serve as a hub for the communication between on- and off-detector electronics.

Fig. 2. TileCal on-electronics system structure Copyright 2017 CERN for the benefit of the ATLAS Collaboration. CC-BY-4.0 license

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The assembly of a Mini-drawer with PMT blocks and electronics is shown in Fig. 3. Three different front-end electronics alternatives have been developed by three institutions in the TileCal collaboration. The “3-in-1” front-end electronics developed by The University of Chicago, USA, the QIE front-end electronics developed by Argonne National Laboratory, USA, and the FATALIC front-end electronics developed by Laboratoire de Physique Clermont-Ferrand, France. One of these will eventually be chosen for the upgrade production. The three alternatives are described in the following subsections.

Fig. 3. PMT blocks and readout electronics in a Mini-drawer Copyright 2017 CERN for the benefit of the ATLAS Collaboration. CC-BY-4.0 license

2.1

The 3-in-1 Front-End Readout Electronics

The upgrade of the 3-in-1 front-end electronics and associated MB is based on the present system used at the LHC [2]. It utilizes commercial off-the-shelf components. The active devices used in the design are selected from the advanced CMOS or BiCMOS technologies, most of them in 130 nm CMOS. A schematic for the hybrid Demonstrator prototype system aimed at the Phase 2 upgrade, equipped with the 3-in-1 front-end readout electronics is shown in Fig. 4.

Fig. 4. The TileCal readout structural diagram using the 3-in-1 front-end electronics Copyright 2017 CERN for the benefit of the ATLAS Collaboration. CC-BY-4.0 license

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In order to be compatible with the current readout system at the LHC, an analog trigger sum is still retained on the new 3-in-1 card. This is necessary for the hybrid Demonstrator, which is aimed for the planned insertion of a few prototype modules in the present ATLAS detector system. A functional diagram of the 3-in-1 card is shown in Fig. 5a. It processes a PMT output signal in two paths: the fast signal processing path and the slow signal processing path. The fast signal processing path receives the PMT signals with a 7-pole passive LC shaper. The shaper output is sent to the high gain and low gain channel in parallel. The high gain and low gain amplifiers have a gain ratio of 32. Both low and high gain amplifiers send the analog signals to the MB for digitization. For compatibility with the current Level-1 trigger, an analog trigger sum is still included on the 3-in-1 card. In Phase 2, the level-1 trigger will transition to fully digital inputs. The latency of the readout electronics is required to meet the fully digital Phase 2 trigger requirements.

Fig. 5. (a) Diagram of the 3-in-1 card, (b) Waveforms of bi-gain channel outputs, (c) Photo of a 3-in-1 card, (d) Dynamic range of the bi-gain system Copyright 2017 CERN for the benefit of the ATLAS Collaboration. CC-BY-4.0 license

The 7-pole passive LC shaper gives an output bandwidth of 1 kHz–12.5 MHz, with effective bandwidth roll-off −140 dB/Dec. The fast PMT output pulse in a rise time of 7–9 ns and a fall time of 17–20 ns is shaped to a waveform like a Gaussian function. The shaper output waveform has a rise time of 25 ns and a fall time of *26 ns and a pulse width of 50 ns FWHM as shown in Fig. 5b. The high-gain channel covers an input dynamic range of 0–25 pC to process the low energy particle signals, such as muons and electrons. The low gain channel covers an input dynamic range of 25–800 pC to process signals generated by large energy hadrons. With 12-bit 40 Mbps ADCs in digitization, the combined bi-gain system achieves input dynamic range of 17 bits as shown in Fig. 5d.

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The TileCal detector cells and PMT gains are calibrated using a Cesium source hydraulically driven through a system of steel tubes traversing all cells of the entire TileCal detector. The slow signal processing path measures PMT responses during the Cesium calibration and monitors the minimum bias current during the proton-proton collisions. The slow signals are measured by a slow integrator with 6 programmable gains having variable time constant of 10–20 ms. A prototype 3-in-1 card is shown in Fig. 5c. The dynamic range of the slow integrator is 0–10 uA with a resolution of 12 bits. 2.2

The QIE Front-End and Readout Electronics

The QIE front-end readout card [4] was developed in a BiCMOS technology. A block diagram of the QIE12 ASIC is shown in Fig. 6a. In principle, it is a 4 range current splitter in ratios of 1/23, 2/23, 4/23 and 16/32. Each range has a gated current integrator. The outputs of 4 integrators are sequentially digitized by a flash ADC (FADC) in multiplexed 4 clock phases from a 40 MHz clock source. A final encoder will sort and encode the 4 FADC outputs to a final digital value for the total charge of a PMT pulse. A time to digital converter (TDC) of 5-bits is also implemented in QIE 12 and read out together with the digitized charge value. The readout data is streamed out word-by-word at a rate of 80 MHz. The data word format consists of 7-bit digitized charge, 2-bit range, 2-bit clock-phase control ID and 5-bit TDC data. The dynamic range of QIE 12 is comprised of 4 ranges having non-linear transfer function shown in Fig. 6b. It presents 18-bit linear dynamic range after calibration with a look-up-table. The resolution and digitization uncertainty varying range by range is shown in Fig. 6c.

Fig. 6. (a) Principle of QIE 12 ASIC, (b) QIE 12 transfer function, (c) QIE 12 resolution and digitization uncertainty Copyright 2017 CERN for the benefit of the ATLAS Collaboration. CCBY-4.0 license

Upgrade of the ATLAS Tile Calorimeter for the High Luminosity LHC

2.3

27

The FATALIC Front-End and Readout Electronics

The FATALIC front-end readout is being developed with IBM 130 nm CMOS Technology [5]. The front-end analog block is a current conveyor that gives 3-outputs with a gain ratio of 64:32:1. The conveyor output pulses are shaped with an RC single pole integrator to a lower bandwidth pulse to meet the Nyquist criterion in 40 MHz sampling ADCs. A functional diagram of FATALIC 4 chip that currently in test is shown in Fig. 7. The on-chip 3 channels of 12-bit ADC cores convert the analog signal to digital data. The auto-range selection allows only 2 channels of data to be read out together for every event, e.g. read out data either from both medium-gain and low-gain channels or from both medium-gain and high-gain channels. The auto-range readout will help reduce the readout data bandwidth. The FATALIC 4 outputs are readout in 12-bit at 80 MHz.

Fig. 7. A functional diagram of the FATALIC 4 ASIC Copyright 2017 CERN for the benefit of the ATLAS Collaboration. CC-BY-4.0 license

The FATALIC 4 front-end electronics can handle a combined dynamic range of 0– 1.2 nC (18-bit). The output electric noise is 7.5 fC and has a non-linearity less than 2% for high and medium gain outputs. An on-chip dedicated electronics block is implemented for the purpose of the die testing. The FATALIC 4 chip operates in +1.6 V single power supply and consumes 205 mW. A new design of FATALIC 5 is planned to eliminate the need for data concentration by the FPGAs on the MB. 2.4

Front-End Electronics Performance and Test-Beam Results

In terms of electronics performance, the systems work well over a large dynamic range and with very low electric noise. All 3 front-end electronics candidates meet the TileCal design requirements in the lab tests. Both prototypes of the 3-in-1 and QIE systems gave very good results in test-beam experiments. The smallest interested low energy muon signals are clearly separated from the background noise in the beam testing for 3-in-1 shown in Fig. 8a and QIE readout systems shown in Fig. 8b.

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However, the test beam testing of FATALIC system is scheduled on the second half of 2017, the results can be reported in the near future.

Fig. 8. (a) 3-in1 test-beam result, (b) QIE test-beam results Copyright 2017 CERN for the benefit of the ATLAS Collaboration. CC-BY-4.0 license

2.5

The Main Board and Daughter Board

As shown in Fig. 9, two different Main Board designs with different functionalities have been built to accommodate the different front-end options, one for the 3-in-1 front-end electronics and a second which is compatible with both the FATALIC and QIE front-end readout electronics [6].

Fig. 9. Two types of Main Boards and the Daughter Board Copyright 2017 CERN for the benefit of the ATLAS Collaboration. CC-BY-4.0 license

The MB for the 3-in-1 front-end electronics has 24 channels of 12-bit 40 Mbps digitizers (LTC2264-12) supporting 12 PMTs in bi-gain channel readout. In order to avoid single point failures in a single centralized system, the MB divides the 12 PMTs to be read out in 4 groups; each group employs a low cost Altera Cyclone IV FPGA

Upgrade of the ATLAS Tile Calorimeter for the High Luminosity LHC

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that serves three 3-in-1 cards for configuration controls via a dedicated SPI bus. Each ADC provides 1-bit serial output at a rate of 560 Mbps sending directly to the DB without routing through the FPGAs. The FATLIC and QIE systems use same MB. FATALIC system uses two FPGAs to convert the 80 MHz, 12-bit ADC parallel data from each PMT to 2-bit serial data stream at a rate of 560 Mbps, which are then transmitted to the DB. By the contrast, the QIE electronics send the parallel data at a rate of 80 MHz directly to the DB. The DB is electronically compatible with all three readout interfaces, but requires different FPGA firmware for each front-end solution. The DB is a data hub responsible for the multi gigabit data communication between the on-detector and off-detector electronics. It receives detector control system (DCS) commands via 4.8 Gbps optical links in GBTX protocol from the off-detector TileProcessor (Tile PPr) module, which in turn collects data from the front-end electronics via the MB and send read out data and DCS monitoring data to the Tile PPrs. Both down-stream and up-stream optical links use redundancy to eliminate single point failures in the system, a failed link can be overcome by switching links at a patch panel in the counting room. This design will not require the duplication of Tile PPr modules.

3 Back-end Electronics The TileCal back-end electronics, Tile PPr will be housed in ATCA chassis, although they will not fully complying with ATCA backplane specifications [7]. A prototype Tile PPr module is shown Fig. 10. It sends trigger, clocks and slow control commands to the DB for the on-detector electronics using the GBTX protocol (4.8 Gbps) and receives the readout data from 4 identical Mini-drawers. The prototype Tile PPr has been designed to allow the testing of all the Phase 2 readout and trigger functionalities and provide backward capability with the current Readout-out Driver (ROD) system for data evaluations. In the Phase 2 runs, the Tile PPr receives data from the on-detector electronics at 40 MHz and transmits the data to a FELIX module for further data acquisition and trigger electronics. The Tile PPr is capable of preprocessing data based on the ATLAS physics requirements.

Fig. 10. Tile PPr Board Copyright 2017 CERN for the benefit of the ATLAS Collaboration. CC-BY-4.0 license

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4 Conclusion The Tile Calorimeter Phase 2 Upgrade design has been successfully tested in the lab and test-beam runs in 2016 with the Demonstrator prototype. All 3 candidates for the front-end analog readout electronics are expected to meet the requirements for implementation in ATLAS. Compared to the current system, the new system is improved in terms of reliability, mechanical assembly, and system installation. In a future winter shutdown, a hybrid Demonstrator prototype with the upgraded calorimeter module and the new calorimeter electronics compatible with the present system, is planned to be inserted in the ATLAS detector for data taking. This will permit all functionality and performance to be fully evaluated.

References 1. Schmidt, B.: The high-luminosity upgrade of the LHC. J. Phys. Conf. Ser. 706, 022002 (2016) 2. Tang, F., et al.: Upgrade analog readout and digitizing system for ATLAS TileCal demonstrator. IEEE Trans. Nucl. Sci. 60(2), 1255–1259 (2013) 3. Tang, F., et al.: IEEE Trans. Nucl. Sci. 62(3), 1045–1049 (2015) 4. Drake, G., et al.: QIE12: a new high performance ASIC for the ATLAS TileCal upgrade. In: Topical Workshop on Electronics for Particle Physics, Lisbon, Portugal (2015) 5. Pillet, N.: FATALIC, a wide dynamic range integrated circuits for the TileCal VFE atlas upgrade. In: TWEPP 2011 - Topical Workshop on Electronics for Particle Physics, Vienne, Austria, September 2011 (2011) 6. Bohm, C., On behalf of the ATLAS Tile Calorimeter System: A hybrid readout system for the ATLAS TileCal phase 2 upgrade demonstrator. In: ATL-TILECAL-PROC-2012-014 7. Carrió, F., et al.: The sROD module for the ATLAS tile calorimeter upgrade demonstrator. In: Proceedings IEEE Nuclear Science Symposium and Medical Imaging Conference, Seattle, WA, USA, November 2014, pp. 8–15 (2014)

Calibration and Performance of the ATLAS Tile Calorimeter During the Run 2 of the LHC Oleg Solovyanov(B) on behalf of the ATLAS Collaboration Institute for High Energy Physics, National Research Center, Kurchatov Institute, Protvino, Russia [email protected]

Abstract. The Tile Calorimeter (TileCal) is a hadronic calorimeter covering the central region of the ATLAS experiment at the LHC. It is a non-compensating sampling calorimeter comprised of steel and scintillating plastic tiles which are read-out by photomultiplier tubes (PMT). The TileCal is regularly monitored and calibrated by several different calibration systems: a Cs radioactive source that illuminates the scintillating tiles directly, a laser light system to directly test the PMT response, and a charge injection system (CIS) for the front-end electronics. These calibrations systems, in conjunction with data collected during proton-proton collisions, provide extensive monitoring of the instrument and a means for equalizing the calorimeter response at each stage of the signal propagation. The performance of the calorimeter and its calibration has been established with cosmic ray muons and the large sample of the proton-proton collisions to study the energy response at the electromagnetic scale, probe of the hadronic response and verify the calorimeter time resolution. This contribution presents a description of the different TileCal calibration systems with the latest results on their performance and the results on the calorimeter operation and performance during the LHC Run 2.

1

Introduction

The Tile Calorimeter [1] is a hadronic non-compensating sampling calorimeter of ATLAS experiment [3] at Large Hadron Collider (LHC) [4] at CERN. It uses steel as a radiator and scintillating tiles as an active medium. The 3 mm thick tiles, made of PSM or BASF polystyrene plus dopants, are oriented perpendicular to the beam axis, and are wrapped in Tyvek paper. The light from the tiles is read out via green wavelength shifting fibers (WLS) fibres, of type Y11 made by Kuraray, connected to the both short edges of the tiles. The WLS fibres are bundled and read out by Hamamatsu R7877 photomultiplier tubes, located in a modules girder, as shown in Fig. 1. The calorimeter is divided into c Springer Nature Singapore Pte Ltd. 2018  Z.-A. Liu (Ed.): TIPP 2017, SPPHY 213, pp. 31–36, 2018. https://doi.org/10.1007/978-981-13-1316-5_6

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3 cylinders: one Long Barrel (with two readout regions LBA and LBC) and two Extended Barrels (EBA,EBC). Each cylinder is further subdivided azimuthally in 64 modules. The calorimeter is 12 m in overall length with 4.25 m outer radius. The Long Barrel module covers the pseudo-rapidity region |η| < 1.0, while the Extended Barrels cover 0.8 < |η| < 1.7. Each module have three longitudinal layers (A,BC,D), with the total thickness in radiation lengths of about 7.4λ. The calorimeter cells are defined by the WLS fiber routing, giving about 5200 cells in all calorimeter with 0.1 × 0.1 Δη × Δφ granularity for A and BC cells, and 0.2×0.1 Δη×Δφ for outer D cells. Analogue trigger sums from pseudo-projective towers are provided for the first level trigger. The dynamic range of the PMTs and associated electronics from 10 MeV to 750 GeV allows for the measurements √ of single particles and large jets. The design resolution for jets is 50%/ E ⊕ 3% and the response is linear within 2% for up to 4 TeV jets [2].

Photomultiplier

Wave-length shifting fiber Scintillator

Steel

Source tubes

Fig. 1. ATLAS Calorimetry and Tile Calorimeter module design [2].

2

Calibration Systems

To provide correct energy and time for data reconstruction, an elaborate chain of calibration systems [5], shown in Fig. 2 is used: – Charge injection system (CIS) to calibrate the response of the ADC – Laser calibration system to measure the performance of the PMTs – Cesium radioactive source system (Cs) to calibrate the full optical path from scintillating tiles and WLS fibres down to integrated current of the PMT – Minimum bias monitoring system (MBM) to monitor the response of the calorimeter online via integrated currents of PMTs About 11% of 192 Tile calorimeter modules were calibrated at the test beams and the electromagnetic (EM) scale (1.05 pC/GeV) was transferred to the final detector with the help of calibration systems [6].

Calibration and Performance of the ATLAS Tile Calorimeter

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Integrator Readout (Cs & Particles)

Particles

Calorimeter Tiles

Photomultiplier Tubes Digital Readout (Laser & Particles)

137

Cs source

Laser light

Charge injection (CIS)

Fig. 2. Tile Calorimeter calibration systems chain [2].

For the charge injection system [7], charges of known values, spanning the full range of ADC (0–800 pC) are injected by a 5.2 pF (±2%) or more precise 100 pF capacitor (±1%) into the passive pulse shaper, that produces a pulse with a Gaussian shape (∼50 ns). Then the pulse is split and sent through two different amplifiers with a gain ratio of 1:64 and then digitized by 40 MHz ADCs. The injection timing with respect to the ADC clock can be varied. The charge injection calibration system allows to simulate a physics pulse from PMT and to calibrate both high and low gain ADCs, although the CIS pulse is shorter and has a “leakage” part. The charge of varying amplitude is injected and the slope of the response vs. injected charge gives the CIS constant for that ADC. The calibration is usually performed twice a week (for a few minutes). Typical uncertainty is 0.7% and the average of calibration coefficients was stable within 0.04% overall in year 2016. The system is also used to calibrate the first level calorimeter trigger. Significant PMT gain drift affects the detector response and calibration, thus the PMT gain monitoring is vital. Laser calibration system [8] delivers 532 nm green light, similar to the light from WLS fibres, via 400 × 100 m long clear fibres to all PMTs. For the LHC Run-2, the Laser optics box and control electronics were upgraded [9] to provide a more precise calibration and monitoring of the PMT gains, with the precision of the gain variation measurement better than 0.5%. A new integrated 6U VME control card allowed to reduce the number of system components. The laser runs are taken twice a week (for a few minutes) and some times a special long (1 h) sequence of runs is taken for precise measurements. In addition to the PMT gain monitoring, the Laser calibration system is used to cross-check problematic channels and to set-up and cross-check timing of the ADC channels. To measure the response of the full optical chain from the scintillating tiles down to PMTs, a system with the movable radioactive gamma-source (137 Cs, 0.662 MeV, 10 mCi) that floats in a dumb-bell shaped capsule inside stainless steel tubes through all the 436000 scintillating tiles of the calorimeter is provided [10]. The integrated PMT currents are read out during the source movement (30 cm/s). The system has been used during the optical instrumentation to check the quality of the assembly. It provides calibration constants and allows

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O. Solovyanov ATLAS Preliminary Tile Calorimeter 0.0

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Fig. 3. Tile Calorimeter PMT gain variation map during 2016 pp collisions period [11].

to transfer the EM scale from the test beam measurements of selected Tile Calorimeter modules to all the Tile Calorimeter. It allows to track the calorimeter response in time and to restore the response uniformity by adjusting the PMT gain via high voltage adjustments. The calibration scans are preformed every few months, each scan takes about 8 h during non-collision time. The measurement precision is better than 0.3% (Fig. 3). Using the same integrated current readout path, the integrated current values are measured during the beam time and stored for later analysis. This data provide additional luminosity measurements and cross-check of other luminometers of ATLAS detector. It provides the transfer of calibration from low to high luminosity conditions, thanks to wide range of measurable currents. The system also allows to follow the evolution of the response of the detector to beam particles between radioactive source scans. The online luminosity is also provided for prompt monitoring. To allow the monitoring of the calorimeter during beam time, an accelerator abort gap of about 3 us is used to send and register calibration pulses, namely the laser ones. To arbitrate, time and control these pulses with respect to the LHC signals, a 6U VME board called SHAFT is used, that contains a pattern memory with configurable delays. Normally the laser pulses are sent to the Tile Calorimeter at the rate of 3 Hz and recorded for further analysis.

3

Performance

To maintain the smallest possible number of “dead” cells and to ensure the highest quality of the data, the on-detector electronics, normally not accessible during data taking, is maintained yearly during detector openings. During the

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winter shut down of 2016–2017, 48 out of 256 electronics “drawers” were opened and all high and many low priority problems were fixed, leading to the 0.06% of “dead” cells after the end of the maintenance. The ever-increasing performance of the LHC led to the increase of the pile-up and hence to the increase of the noise levels, well above the pure electronics noise that stays below 20 MeV for the most of the cells, while the pile-up noise can reach 160 MeV for the inner layer of the calorimeter cells. The time calibration resolution reaches 1 ns level for energies above 4 GeV in one cell. The timing is initially set with splashes and tuned later with muons and jets. The stability of the time settings during the data taking is monitored with the laser pulses in empty bunches of LHC abort gap, described above. One of the goals of the sophisticated chain of calibration systems is to monitor the response variation of Tile Calorimeter in time, as the cell response is not constant due to PMT gain variation and scintillator degradation. One of the most exposed cells of inner calorimeter layer have shown as much as 2% difference between the Laser (sensitive to PMT gain variation only) and integrated currents (sensitive to PMT gain variation and scintillator degradation) responses. While one can see some recovery during 2015 data taking of LHC Run-2, there was almost no recovery in the following, high luminosity data taking period of 2016, as shown in Fig. 4.

5000 28/06 2016

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An important Tile Calorimeter characteristic is the ratio of energy to track momentum (E/p) for isolated, charged hadrons in minimum bias events, and it is used to evaluate calorimeter uniformity and linearity during data taking. The data and simulation agree well, showing linearity and uniformity in detector response, the dE/dx of minimum ionizing muons (near noise threshold) show data and Monte-Carlo (MC) agreement within 3%. Muons from cosmic rays, beam halo and collisions are used to study in-situ the electromagnetic energy scale. Only 1% response non-uniformity in η is seen in Tile Calorimeter Long Barrel, with a good energy response uniformity in all calorimeter layers and the data and simulation agreement.

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One of the main use of the hadronic Tile Calorimeter is the measurement of jet energy and missing transverse energy (MET). The data and MC simulations agree well, the jet energy scale is consistent and the jet energy resolution is below 10% for pT > 100 GeV. The constant term is within expected 3%.

4

Summary

The hadronic Tile Calorimeter is a key detector to measure jet energy and missing transverse energy in ATLAS experiment at LHC. To calibrate and monitor the calorimeter response a set of calibration systems is used, that allowed to achieve great performance of Tile Calorimeter in LHC Run 2 with better than 1% precision.

References 1. ATLAS Collaboration: ATLAS Tile Calorimeter: Technical Design report, CERNLHCC-96-42 (1996). https://cds.cern.ch/record/331062 2. ATLAS Collaboration: Readiness of the ATLAS Tile Calorimeter for LHC collisions. Eur. Phys. J. C 70, 1193 (2010) https://doi.org/10.1140/epjc/s10052-0101508-y 3. ATLAS Collaboration: The ATLAS experiment at the CERN large Hadron Collider. JINST 3, S08003 (2008). https://doi.org/10.1088/1748-0221/3/08/S08003 4. Evans, L., Bryant, P.: LHC machine. JINST 3, S08001 (2008). https://doi.org/10. 1088/1748-0221/3/08/S08001 5. Boumediene, D., et al.: C alibration of the Tile Hadronic Calorimeter of ATLAS at LHC. J. Phys. Conf. Ser. 587(1), 012009 (2015). https://doi.org/10.1088/17426596/587/1/012009 6. Adragna, P., et al.: Testbeam studies of production modules of the ATLAS tile calorimeter. Nucl. Instrum. Meth. A 606, 362 (2009). https://doi.org/10.1016/j. nima.2009.04.009 7. Anderson, K., et al.: Design of the front-end analog electronics for the ATLAS tile calorimeter. Nucl. Instrum. Meth. A 551, 469–476 (2005). https://doi.org/10. 1016/j.nima.2005.06.048 8. Abdallah, J., et al.: The Laser calibration of the Atlas Tile Calorimeter during the LHC Run 1. JINST 11, T10005 (2016). https://doi.org/10.1088/1748-0221/ 11/10/T10005 9. Scuri, F., at al.: Performance of the ATLAS Tile LaserII calibration system. In: Proceedings, 2015 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC 2015) (2015). https://doi.org/10.1109/NSSMIC.2015.7581768 10. Starchenko, E., et al.: Cesium monitoring system for ATLAS Tile Hadron Calorimeter. Nucl. Instrum. Meth. A 494, 381 (2002). https://doi.org/10.1016/S01689002(02)01507-3 11. ATLAS Tile Calorimeter Subsystem, Approved Plots. https://twiki.cern.ch/twiki/ bin/view/AtlasPublic/ApprovedPlotsTile. Accessed 22 May 2017

Performance Studies and Requirements on the Calorimeters for a FCC-hh Experiment C. Neub¨ user(B) on behalf of the FCC-hh Detector Working Group CERN - European Laboratory for Particle Physics, 1211 Geneve 23, Switzerland [email protected]

Abstract. The physics reach and feasibility of the Future Circular Collider (FCC) with center of mass energies up to 100 TeV and unprecedented luminosity is currently under investigation. This energy regime opens new opportunities for the discovery of new heavy particles (new gauge bosons), as well as new precise measurements in the Higgs sector (self-coupling, rare decays). However, high mass gauge bosons or high pT vector bosons decaying to pairs of hadrons require an efficient reconstruction of very high pT jets. The reconstruction of these boosted jets (∼5–20 TeV), with a large fraction of highly energetic hadrons, sets the requirements on the calorimetry: excellent energy resolution (especially low constant term), containment of highly energetic hadron showers, and high transversal granularity to provide sufficient distinction of close by objects. Additionally the FCC detectors have to meet the challenge of a very high pile-up environment. We will present the preliminary results of the ongoing performance studies, discuss the feasibility and potential of the technologies under test, while addressing the needs of the physics benchmarks of the FCChh experiment for the calorimeters.

1

Introduction

The collaboration around the Future Circular Collider (FCC) project studies the next generation of circular colliders for electron-electron (ee), hadron-hadron (hh) and electron-hadron (eh) collisions with desired center-of-mass energies of up to 100 TeV. Therefore, the construction of a 100 km tunnel in the Geneva area is under investigation. Hereby CERN functions as the host laboratory and provides necessary infrastructure. The high energy and intensity require new developments of magnets and RF structures for the accelerator, as well as new experiment and detector designs. Within this paper we will elaborate on the key requirements on the detectors, with the focus on the calorimeters, and introduce the current design proposal that is used as a reference for the conceptional design report in preparation for the FCC study. c Springer Nature Singapore Pte Ltd. 2018  Z.-A. Liu (Ed.): TIPP 2017, SPPHY 213, pp. 37–43, 2018. https://doi.org/10.1007/978-981-13-1316-5_7

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FCC-hh Experiment

The new energy regime of a FCC-hh experiment opens new possibilities to probe the Standard model. An interesting study is the Higgs production in vector boson fusion (VBF) processes which give access to a range of Higgs properties and allows for dark matter searches in invisible Higgs decays [1]. However, the associated jets will carry low transverse momentum and thus appear at high pseudo-rapidities in the detector. This sets the requirements of the detector to cover η ranges of up to 6, which corresponds to a distance from the beam-pipe of 2 cm at a distance of 10 m to the interaction point. Therefore a forward tracking system is proposed to cover η > 2.5 to η = 6, see Fig. 1. This requires two additional solenoids, which provide a magnetic field of 4 T. The ultimate running scenario reaches a luminosity of 30 × 1034 cm−2 s−1 ; with a bunch spacing of 25 ns, and an average of 1,000 proton-proton collisions. After 25 years of operation this sums up to approx. 30 ab−1 . One of the challenges arising from these conditions is the need to resolve the pile-up events that are on average expected to be separated by 170 μm in space and 0.5 ps in time. This sets the requirements on the spacial and timing resolution of the tracking system and becomes especially challenging for η > 2.5 [3]. Another challenge are the large data rates, produced by the large amount of channels of the detector systems and the expected high occupancy. Investigations on how to deal with hundreds of TB/s started within the collaboration. Additionally, most of the instruments have to withstand extreme radiation. The expected radiation levels are shown in terms of 1 MeV neutron equivalent

Fig. 1. The FCC-hh reference detector. The tracking system is shown in grey, the electromagnetic calorimeters (ECALs) are shown in dark blue and the hadronic calorimeters (HCALs) are shown in light green and blue. The E- and HCALs in the Barrel and Endcap regions sit within the central solenoid. The muon chambers are shown in yellow and orange [2].

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fluence in Fig. 2, which illustrates the need for a 50 times radiation harder inner pixel detector than planned for the High-Luminosity upgrade of the LHC.

a) Layout

b) 1 MeV neq fluence

Fig. 2. (a) The reference layout of the detector systems in y-z [4]. (b) The FLUKA simulations [5] of the expected 1 MeV neutron equivalent fluence in the FCC-hh reference detector after 30 ab−1 [6].

2.1

FCC-hh Calorimeters

The FCC-hh reference calorimeter system consists of electromagnetic and hadronic sections, in the Barrel and extended Barrel (B and EB) η < 1.5, Endcap (EC) 1.5 < η < 2.5, and Forward (F) η > 2.5 regions. In the areas most strongly exposed to radiation, the reference detector is equipped with Liquid Argon (LAr) calorimeters (based on lead absorbers and LAr as active material) [7], while the outer barrel regions are covered by a Scintillator-Stainless Steel hadron calorimeter based on the ATLAS TileCal design [7]. This combined system has proven good performance in the ATLAS experiment, however for the new energy frontier reachable with the FCC, the calorimeter technologies have to be further developed to provide the necessary performance in jet reconstruction.

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This requires higher transverse and longitudinal granularity for particle shower separation, reconstruction algorithms e.g. particle flow, and pile-up rejection. Additionally, the depth in terms of nuclear interaction lengths has to be sufficient to provide full containment of hadrons with energies up to 10 TeV [8]. To achieve the best possible energy resolutions for single particles and jets at very high energies, the constant term b of the energy resolution, following Eq. 1, has to be kept as small as possible. σErec a = √ ⊕b Erec  E

(1)

The constant term is dominated by shower leakage and uncertainties on the calibration, while the stochastic term a is dominated by the sampling fluctuations of a calorimeter and additionally increase in hadronic calorimeters in case of noncompensation and the fluctuations in the invisible shower components. For full simulations of the FCC-hh reference detector a new software framework is in development [9], which currently includes the tracking and calorimeter system in the Barrel and Endcap regions. The material budget is shown in Fig. 3 and shows the η coverage up to 2.5. Figure 3(b) illustrates that a coverage of 11 λ is achieved, except for around η ∼ 1.7. In order to overcome this depth deficit an increase in z of the length of the HCAL EB of 50 cm is needed and will be implemented in the new detector layout. The number of radiation lengths, see Fig. 3(a) are especially important for the muon detection outside the solenoids. The degradation of the muon momentum measurement by multiple scattering in the calorimeters is currently under investigation.

Fig. 3. Material budget of the FCC-hh reference detector in terms of radiation lengths X0 in (a) and nuclear interaction lengths λ in (b).

2.2

Electromagnetic Calorimeter

In terms of energy resolution, the electromagnetic calorimeter is required to √ % ⊕ 1 % to achieve a resolve electrons and photons with at least a precision of 10 E

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41

precise Higgs mass measurement for H → γγ. Additionally, the non-linearities of the calorimeter have to be on the sub-percent level to sufficiently suppress the systematic uncertainties on the physics searches. The reference LAr ECAL Barrel calorimeter is tested in simulation using lead plates as absorbers. The geometry of the ECAL layers is simplified compared to the ATLAS design by arranging the active layers with an inclination angle of 30◦ . By this the longitudinal segmentation can be increased, which results in an increase of the sampling fraction with the radius and requires a correction within the calibration. After the calibration and a correction of the lost energy within the cryostat providing the cooled Argon, the single electron reconstruction achieves and exceeds the required energy resolution, see Fig. 4(a). However, the effects of electronic noise and noise originating from the large number of pile-up events is not yet included in the simulations. (〈Etot〉-Ebeam)/E

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Fig. 4. The energy resolution and non-linearity obtained for single electrons and pions with the FCC-hh reference calorimeter system consisting of the LAr ECAL and Sci/Steel HCAL. (a) shows the resolution of the ECAL for electron energies up to 1 TeV. (b) shows the combined performance of E + HCAL on the EM scale for single pions at η = 0.36. All resolutions are extracted from Gaussian fits performed in the range ±2σ.

2.3

Hadronic Calorimeter

The hadronic calorimeter for a FCC-hh experiment has to fulfil three major tasks; First it has to reconstruct jets in forward regions up to η = 6. Second, it needs to contain the high-energy hadron showers, which requires a thickness of the whole calorimeter system of ≈11λ. And third, the transverse and longitudinal granularity has to be high enough to distinguish between close by, boosted objects.

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The reference hadron calorimeter is a Scintillator-Steel sampling calorimeter, based on the ATLAS design, with an increased granularity to Δη×Δϕ = 0.025× 0.025 and 10 longitudinal layers. This design is currently under test within full simulations and achieves an energy resolution (with a depth of 9.3 λ at η = 0.36) % for single pions up to 10 TeV of σEE = 42.4 E ⊕ 3.3 %. This calorimeter is noncompensating (e/h = 1.23) which intrinsically degrades the energy resolution of hadronic showers, but it also motivates the application of algorithms that reweight the calorimeter cells to optimise the calorimeter resolution. Thus further improvement can be expected using so-called software compensating algorithms. The combined calorimeter system has been tested for the energy reconstruction of single pions with both systems calibrated to the EM scale. The energy resolution and non-linearity, without further corrections for the dead material between the calorimeters nor for the non-compensation, are shown in Fig. 4(b) and compared to the performance of the HCAL only. The large non-linearity is expected due to the energy losses in the cryostat of the ECAL and can be eliminated by additional corrections applied during the energy reconstruction. 2.4

Technological Options

Additional technological options for the calorimeters are currently taken under consideration. For the ECAL parts of the FCC-hh detector a Silicon-Lead sampling calorimeters following the CMS Phase II Endcap upgrade design [10] is planned to be further tested in simulations and the experiences and performance results within the CMS collaboration will be followed with high interest. Another option for the ECAL is also based on Silicon-Lead technology, however considering digital signal information of Monolithic Active Pixel Sensors (MAPS). This technology is also considered for the forward calorimeter upgrade for the ALICE experiment and first simulation studies for the FCC-hh experiment have started and show promising results. However, these Silicon based technologies can only be considered in the barrel regions of the FCC-hh detector due to radiation tolerances. An option for the hadronic calorimeter in the barrel region is the ScintillatorSteel sampling calorimeter following the CALICE Analogue Hadron Calorimeter (AHCAL) design, that has a classical sampling geometry with an integrated readout. This technology has been developed for the future electron-positron collider ILC, but is currently being adjusted for the CMS experiment which again rises the attention within the FCC-hh collaboration.

3

Outlook

The FCC-hh detector design is based on the experiences from the running LHC experiments, including adjustments to the new energy regime reachable with the FCC machine. The current efforts focus on the completion of the conception design report to provide the input for the next European strategy update in 2019.

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The simulation of the reference calorimeter system of the FCC-hh experiment has proven good performance for single particle reconstruction. Further optimisation studies concerning material, total depth, η coverage and geometry are on-going. Finally the system has to demonstrate good performance in the high pile-up environment and in jet reconstruction, especially for boosted topologies.

References 1. Goncalves, D., Plehn, T., Thompson, J.M.: Weak Boson Fusion at 100 TeV. Phys. Rev. D95(9), 095011 (2017). arXiv:1702.05098 2. H.F.P. Da Silva for the FCC Detector Magnets Working Group: FCC-hh Detector integration and opening-closing scenario, talk at FCC Week 2017. (http://www. fccw2017.web.cern.ch) 3. Z. Dr´ asal, M. Mannelli On behalf of the FCC-hh detector working group: Tracker design overview, talk at FCC Week 2017. (http://www.fccw2017.web.cern.ch) 4. W. Riegler for the FCC Hadron Detector Working Group: FCC-hh Detector and Experiments CDR Outline and Status, talk at FCC Week 2017. (http://www. fccw2017.web.cern.ch) 5. FLUKA is a fully integrated particle physics Monte Carlo simulation software package. www.fluka.org/ 6. Besana, M.I., Cerutti, F., Ferrari, A., Vlachoudis, V., Riegler, W.: Radiation Environment, talk at FCC Week (2017. (http://www.fccw2017.web.cern.ch) 7. ATLAS collaboration: The ATLAS experiment at the CERN Large Hadron Collider. JINST 3, S08003 (2008) 8. Carli, T., Helsens, C., Henriques Correia, A., Solans Snchez, C.: Containment and resolution of hadronic showers at the FCC. JINST 11, P09012 (2016). https://doi. org/10.1088/1748-0221/11/09/P09012 9. http://fccsw.web.cern.ch/fccsw/ 10. Magnan, A.-M.: HGCAL: a High-Granularity Calorimeter for the endcaps of CMS at HL-LHC. JINST 12, C01042 (2017)

Precision Timing Calorimetry with the Upgraded CMS Crystal ECAL Adi Bornheim(B) on behalf of the CMS Collaboration Caltech, E. California Blvd., Pasadena, CA 91125, USA [email protected]

Abstract. Particle detectors with a timing resolution of a few 10 ps allow to improve event reconstruction at high luminosity hadron colliders tremendously. The upgrade of the Compact Muon Solenoid (CMS) crystal electromagnetic calorimeter (ECAL), which will operate at the High Luminosity Large Hadron Collider (HL-LHC), will achieve a timing resolution of around 30 ps for high energy photons and electrons. In this talk we will discuss the benefits of precision timing for the ECAL event reconstruction at HL-LHC. Simulation and test beam studies carried out for the timing upgrade of the CMS ECAL will be presented and the prospects for a full implementation of this option will be discussed. Keywords: Calorimeter · Picosecond timing Radiation hard scintillators

1

· LHC

Introduction

The Large Hadron Collider (LHC) at CERN is scheduled to be upgraded to increase the instantaneous luminosity it can deliver by about a factor 5 to 7 over the current performance. The physics goal of this High Luminosity phase of the LHC (HL-LHC) is to perform precision studies of the Higgs boson production, decay kinematics and rates as well as the measurement of the Higgs self coupling. This will be a crucial test of the SM electroweak symmetry breaking sector. Searches for physics beyond the standard model will also be conducted. To achieve these goals an integrated luminosity of at last 3, possibly more than 4.5 ab−1 has to be accumulated. The data taking for HL-LHC will last for 10 years. The detector performance during this period needs to be maintained at a level achieved during LHC Run I in the first 3 years of LHC operation. The instantaneous luminosity target is set to 1035 cm−2 s−1 [1] or above. This requires the operation of the HL-LHC at beam intensities that will result in 200 simultaneous proton-proton collisions (PU) per bunch crossing. Precision timing capabilities of the LHC detectors are a crucial new technique to maintain the physics performance of the event reconstruction under such high rate data taking conditions. With a timing precision of a few 10 ps, c Springer Nature Singapore Pte Ltd. 2018  Z.-A. Liu (Ed.): TIPP 2017, SPPHY 213, pp. 44–48, 2018. https://doi.org/10.1007/978-981-13-1316-5_8

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equivalent to a spatial resolution of a few mm, final state objects such as tracks and calorimeter clusters, can be assigned to primary vertices by using time-offlight (ToF) techniques. The CMS Collaboration is envisioning the concept of a holistic event reconstrution where all tracks and calorimeter clusteres will have a time measurement with a precision of a few 10 ps. In this paper, we describe the usage of precision timing for high energy photons in the CMS detector and the upgrades of the CMS ECAL for HL-LHC which will improve its timing measurement precision to about 30 ps for photons of around 10 GeV and above.

2

Applications of Precision Timing Measurements for High Energy Photons in CMS

Physics signatures with high energy photons in the final state are particularly vulnerable to the effect of PU, as photons do not have tracks which would allow to link them to their vertex of origin. In LHC Run I data it was typically sufficient to select the photons with the highest transverse momentum (pT ) to identify them as the decay products of eg. Higgs bosons. In HL-LHC data this will not be sufficient any more. The probability of a PU event containing a photon of similar of higher pT as the ones from Higgs decays becomes significant. The efficiency of finding the correct vertex of a Higgs boson decay vertex using the photon pT as the main discriminant will decrease from above 80%, as achieved in LHC Run I, to below 40% in the presence of 200 PU events. The ability to trace the origin of the photons with ToF techniques will allow to separate randomly combined ones from ones stemming from a common vertex. The fundamental principle is illustrated in Fig. 1. With a precise measurement of the photon location and time in the calorimeter and the constrained on the x- and y-position of the beam axis, the z-position and time of the common vertex of origin of the two photons can be calculated analytically. The technique is equivalent to a satellite based navigation system. The achievable precision scales with the timing resolution. A timing resolution of 30 ps for each of the two photons in a Higgs decay translates into a vertex resolution of better than 1 cm. Similar techniques can also be applied to assign or reject neutral calorimeter clusters to jets or to isolation cone variables around leptons and photons. In the context of the HL-LHC upgrade the CMS collaboration is also investigating the option to enhance the timing performance of the endcap calorimeter replacement to the level of a few 10 ps, as well as the option to install a precision timing detector for charged particles to assign time stamps to all tracks [3] (Fig. 2).

3

The Upgrade of the CMS ECAL for HL-LHC

The CMS ECAL is a high-resolution, homogeneous electromagnetic calorimeter made of 75,848 scintillating lead tungstate crystals [4]. The crystal matrix of the ECLA barrel, consisting of about 60000 crystals, will be preserved for HL-LHC.

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Fig. 1. Illustration of the reconstruction of an event vertex using the time-offlight of two photons. With a precise measurement of the photon location and time in the calorimeter and the constrained on the x- and y-position of the beam axis, the z-position and time of the common vertex of origin of the two photons can be calculated analytically.

Fig. 2. Impact of photon timing measurement on the mass measurement of Higgs bosons decaying into two photons. The improved vertex reconstruction efficiency results in an improved invariant mass resolution.

The very frontend electronics (VFE) will have to be replaced to cope with the higher trigger and readout rates, the increased dark current induced noise in the avalanche photo detectors (APD) as well as fake signals induced by nuclear counter effects in the APD. As the APD attachment to the crystals is deeply integrated into the mechanical support of the ECAL it is not practical to replace it during the upgrade [6]. The large, temporally coherent, primary signals generated in these crystals, the scintillation light, make them ideal sensors for precision timing measurements. Already during LHC Run I the timing resolution of the calorimeter was found to be around 190 ps for clusters from electrons stemming from the decay of Z bosons [5]. The constant term of the time resolution was measured to be 20 ps in the test beam. Detailed studies of the systematic effects impacting the timing resolution identified the precision of the electronic clock synchronizing the VFE as the primary limitation to the timing precision achieved in LHC Run I. The replacement of the VFE will offer the opportunity to improve the clock stability to the required level. The impedance of the APD, in combination with its cable connection to the VFE, results in an effective high pass filter with an upper frequency cutoff at around 35 MHz, resulting in a minimal achievable signal rise time of the analog APD risetime of around 20 ns. This limits the bandwidth requirement for the subsequent amplification to this range. A trans-impedance amplifier (TIA) with a subsequent digitization at 160 MHz was found to optimally exploit the timing capability of the existing crystals in combination this the APD.

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In Fig. 3 we show the timing resolution achieved in a test beam measurement with a TIA prototype, digitized with a 5 GHz ring-sampling digitizer. By downsampling to a rate of 160 MHz in the offline data analysis it is demonstrated that this is a sufficient sampling rate to optimally exploit the analog output form the TIA. A time resolution of around 30 ps is achieved for an effective amplitude equivalent to an energy deposit of around 25 GeV in the ECAL crystals. Throughout the operational life of HL-LHC the radiation induced increase off the APD dark current will degrade this performance to about 30 ps for energy deposits of 60 GeV and above. This will be sufficient to get good timing measurement for the majority of photons used in a Higgs analysis.

Fig. 3. Time resolution measured with a 5 × 5 CMS ECAL crystal matrix read out with a prototype VFE based on a TIA and a 5 GHz digitizer. A time resolution of around 30 ps is achieved for an effective amplitude equivalent to an energy deposit of around 25 GeV.

Fig. 4. Time spectrum of the scintillation light arriving on the APD at the end of a CMS ECAL crystal. The rise time of about 3 ns is driven by the dispersion of the light traveling through the crystal from different locations along the shower.

Aside from the clock distribution and the bandwidth limitations of the APD we also studied the temporal structure of the primary signal creation and propagation in the P bW O4 crystal. The scintillation light output signal rise time has been measured to be on the order 60 ps [2]. The temporal structure of the scintillation light arriving at the photo sensor is shaped by several effects. The shower process in the crystal propagates with the speed of light, spreading it out over about one nanosecond along the 25 cm long crystal [5]. The propagation speed of the scintillation light from the location it is created at to the photo sensor at the end of the crystal is reduced by the refractive index of P bW O4 , which is larger than 2. There is further dispersion of the time structure due to internal reflection of scintillation light that is not emitted directly onto the photo

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sensor, increasing the travel time of these photons inside the crystal. In Fig. 4 we show a simulation of the time structure of scintillation photons arriving on the APD sensor of a CMS ECAL crystal. The rise time of the signal is about 3 ns, driven by the dispersive effects described above. The effects of the shower propagation and light transport in the crystal on the timing resolution of the detector are negligible since the signal risetime arriving at the digitizer of the VFE is dominated by the effective APD bandwidth. For future calorimeters with faster photo detectors however such effects may become dominant.

4

Summary

Precision timing can be a powerful handle to mitigate pile-up effects at HLLHC. The upgrade of the CMS detector for the HL-LHC will enhance the timing performance of the CMS ECAL crystal calorimeter to achieve a timing resolution of around 30 ps for energy deposits of 25 GeV. This will allow to reconstruct photon vertices with a precision of around 1 cm, significantly enhancing the event reconstruction under high PU conditions. The timing performance of the CMS ECAL after the upgrade will be limited by the effective bandwidth of the APD. With faster photo detectors the timing precision could be improved further.

References 1. Rossi, L., Bruning, O.: High Luminosity Large Hadron Collider A description for the European Strategy Preparatory Group, CERN-ATS-2012-236. https://cds.cern. ch/record/1471000 2. Derenzo, S.E., Weber, M.J., Moses, W.W., Dujardin, C.: Measurements of the intrinsic rise times of common inorganic scintillators. IEEE TNS 47, 860–864 (2000) 3. The CMS Collaboration: CMS Phase II Upgrade Scope Document, CERN-LHCC2015-019 4. CMS collaboration: The CMS electromagnetic calorimeter project: Technical Design report, CERN-LHCC-97-33 (1997) 5. The CMS Collaboration: Electron and photon energy calibration and resolution with the CMS ECAL at sqrt(s) = 7 TeV. JINST 8, P09009 (2013). https://doi.org/ 10.1088/1748-0221/8/09/P09009. CERN-PH-EP-2013-097 6. Barria, P.: TIPP2017, these proceedings 7. The CMS Collaboration: Timing performance of the CMS electromagnetic calorimeter and prospects for the future, CMS-CR-2014-141, PoS: TIPP2014 (2014)

Construction and First Beam-Tests of Silicon-Tungsten Prototype Modules for the CMS High Granularity Calorimeter for HL-LHC Francesco Romeo(B) On behalf of the CMS collaboration Institute of High Energy Physics, Beijing, China [email protected]

Abstract. The High Granularity Calorimeter (HGCAL) is the technology choice of the CMS collaboration for the endcap calorimetry upgrade planned to cope with the harsh radiation and pileup environment at the High-Luminosity LHC. The HGCAL is realized as a sampling calorimeter, including an electromagnetic compartment comprising 28 layers of silicon pad detectors. Prototype modules, based on hexagonal silicon pad sensors have been constructed and tested in beams at FNAL and at CERN. We present the construction and first beam-tests of these modules both in the laboratory and with beams of electrons, pions and protons, including noise performance, calibration with minimum ionizing particles, electron relative energy and position resolutions and precisiontiming measurements.

1

Introduction

The CMS collaboration will replace its current endcap calorimeters with a silicon-based High Granularity Calorimeter (HGCAL) for the High-Luminosity LHC era, in order to sustain the high radiation and guarantee excellent-quality object reconstruction and identification in the dense pileup environment. The HGCAL is a sampling calorimeter that includes both electromagnetic (lead absorber and hexagonal silicon sensors) and hadronic (stainless steel absorber and silicon or scintillators detectors) sections. More details on HGCAL detector and the motivations for building it can be found in [5]. We discuss the construction and first beam-tests of silicon-tungsten prototype modules and the beam-test of irradiated and unirradiated diodes performed in 2016. The aim is to validate the HGCAL design concept based on silicon sensors, whilst evaluating their performance and comparing them with a detailed simulation.

c Springer Nature Singapore Pte Ltd. 2018  Z.-A. Liu (Ed.): TIPP 2017, SPPHY 213, pp. 49–55, 2018. https://doi.org/10.1007/978-981-13-1316-5_9

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Experimental Setup for the Study of Silicon-Tungsten Modules

In this section, we describe the silicon sensors used and the corresponding module assembly, the data acquisition system, and the data-taking setup and conditions for the beam tests of part of the electromagnetic section of the HGCAL. 2.1

Silicon Sensors and Module Assembly

The used silicon sensors are n-type with a physical (depleted) thickness of 320 (200) µm. Each hexagonal silicon sensor, cut from 6” wafers, has 128 readout cells. Most of these cells are 1.1 cm2 in size and are hexagonal in shape, except for two central cells used for calibration that have 1/9 of the standard size, and some cells around the edges that have variable size and shape. Figure 1a shows an example of such a module and Fig. 1b the module assembly. Each module has a copper-tungsten (25%Cu:75%W) hexagonal baseplate with coefficient of thermal expansion close to that of silicon. The baseplate provides mechanical rigidity to the module and is part of the calorimeter absorber. It is glued, using Araldite 2011 non-conductive epoxy, to a polyimide gold-surfaced sheet, which allows for the biasing of the back side of the silicon sensor. The polyimide foil is then glued to the sensor itself and the sensor to a first PCB, which connects electrically to the front side of the silicon cells with aluminium wire bonds through holes in the PCB and routes these signals to two small connectors. A second “readout PCB”, connected to the first, contains the front-end electronics and connectors to the outside world. An existing ASIC has been used: the “Skiroc2” [2] developed for the CALICE collaboration [4]. Each Skiroc2 has 64 channels, with each channel having a preamplifier and two separate slow shapers (with gain ratio 10:1), a fast shaper, self-trigger and fifteen-cell pipeline, as well as a 12-bit ADC. Only the slow shapers were used in our system, since we utilized an external trigger, while the fast shaper is used for self-trigger. Two Skiroc2 ASICs were mounted on each readout PCB.

(a)

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Fig. 1. (a) A 128-cell hexagonal silicon sensor. (b) The assembly of 1 of the modules. From CMS-CR-2017-169. Published with permission by CERN.

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Data Acquisition System

Figure 2a shows a photograph of the full DAQ chain, which uses commercial components mounted on custom PCBs. The data from the Skiroc2s are first transferred from the module to an intermediate “elbow board”, which provides the bias voltage (operation voltage of the sensors is 120 V), and then moved to a dual daughterboard carrier (DDC) card through polyimide cables. These DDC hosts two “FMCIO” mezzanines, utilizing standard FMC connectors and incorporating Xilinx XC7A100T “Artix” FPGAs, and routes the signals from two FMCIO (hence two modules) to a standard HDMI connector. The “Zedboard” then accumulates data through another passive custom board, known as the “ZEDIO”. The final link is from the Zedboard to a standard PC via ethernet.

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Fig. 2. (a) The DAQ system. The yellow arrows represent the data path. (b) FNAL experimental setup. (c) “CERN setup II” experimental setup. From CMS-CR-2017-169. Published with permission by CERN.

2.3

Data Taking at FNAL and CERN

The data taking at FNAL and CERN has been carried out with 3 configurations. At FNAL, 16 modules were available, arranged as double-sided layers interspersed with tungsten absorbers, for a total thickness of about 15 X0 , as shown in Fig. 2b. Electrons with energies in the range [4–32] GeV and protons with energies of 120 GeV were used. A single 2 × 2 cm2 scintillator was used as a trigger, as readout devices in coincidence. At CERN, 8 modules were used in 2 schemes: “CERN setup I”, having the modules placed between about 6 X0 and 15 X0 , and “CERN setup II”, shown in Fig. 2c, with modules covering from 5 X0 to 27 X0 . Electrons with energies in the range [20–250] GeV and pions with energies of 125 or muons decaying from pions of 120 GeV were used. The trigger was based on two consecutive scintillators in coincidence, with the one closest to the detector defining the trigger size of 4 × 4 cm2 . The various setups described in the previously are simulated with GEANT4 [6], using the FTFP BERT EMM (the default one used in CMS [3]) and QGSP FTFP BERT physics lists.

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Performance of Silicon-Tungsten Modules

In this section, we summarize the results of the measurements related to the properties of the silicon-tungsten modules described in Sect. 2. The raw information provided as input from the DAQ is processed through a dedicated analysis framework implemented in the standard CMS software. The energy deposited in each cell is calibrated in terms of minimum ionizing particle, “MIP”, as follows. First, the pedestal and a common mode noise, found in the cells of the modules when the bias voltage is applied, are subtracted from the ADC count (the pedestal RMS and noise RMS are found to be stable within 2 ADC counts). Then, the corrected ADC counts are converted to MIPs using the single-particle response curves in a cell of the detector originated from proton (FNAL) and pion or muon (CERN) beams. Since proton and pion at the energies mentioned are not strictly minimum ionizing, the obtained single particle response was suitably corrected using inputs from simulation. 1 MIP is found to be approximately 17 ADC counts, from the calibration on the cells of sensors within the trigger area. 3.1

Transverse and Longitudinal Shower Shapes

Figure 3a illustrates an example of the energy deposit from an electron crossing a hexagonal module. The red cell represents the cell with the highest energy release, E1 , while the orange (green) ones the 6 (12) cells in the first (second) ring around it, so that E7 (E19 ) is the energy sum in these cells and the ones inside them. From these cells some quantities can be defined to study the transverse profile, such as the E1 /E7 ratio, which is displayed in Fig. 3b.  8

(E X

)

8 i 0,i , The longitudinal shower barycentre is instead defined as t = i=1 i=1 Ei where Ei is the layer energy and X0,i the total calorimetric radiation length up to layer i, and is illustrated in Fig. 3c. These two examples for studying the transverse and longitudinal electron shower profiles show a very good agreement between the data and the simulation.

3.2

Energy Measurement and Resolution

The energy of showering electrons is reconstructed from the sum of the individual energies, exceeding a threshold of 2 MIP, deposited in all the cells and the modules. This quantity, which represents only the energy released in the active layers, is combined with sampling factors reflecting the dE/dX for MIPs in the absorbers to give the final energy measurement. The cores of the obtained energy distributions are fitted with Gaussian functions and the resulting mean and σ values are taken as the mean energy response and the energy resolution of the detector. Figure 4a shows the relative energy resolution as a function of the beam energy for both data and simulation. The FNAL and CERN setup II configurations are displayed on the same canvas to emphasize the different sampling regimes of the two setups. An energy resolution

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Fig. 3. (a) Event display of the energy seen in a module due to electron-induced electromagnetic showers. (b) Example of distribution for the study of the transverse profile. (c) Example of distribution for the study of the longitudinal profile. From CMS-CR2017-169. Published with permission by CERN.

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Fig. 4. (a) Relative energy resolution as a function of the electron energy. (b) Residual widths of the X-coordinate reconstruction on the first sensitive layer as a function of incident electron energy. (c) The intrinsic precision of the HGCAL sensors X-coordinate measurement for all layers and for all energies. From CMS-CR-2017-169. Published with permission by CERN.

below about 7%, for an electron energy > 50 GeV, can be achieved. We can see that the limited longitudinal samplings clearly limit the possible electron energy resolution that is achievable but that the simulation matches the data at the 5% level for all the studied energies. 3.3

Position Measurement and Resolution

The position is measured as the difference between the track position, extrapolated from two wire chambers upstream of first HGCAL module, and the electron shower position, taken as the logarithmic weight of the energy deposited in the E19 cluster, using CERN setup I. The width of the distribution of this residual is considered as the position resolution of a given sensor. Figure 4b shows the X-coordinate resolution on the first sensitive layer as a function of incident electron energy. Figure 4c shows the intrinsic precision of the

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HGCAL sensors’ X-coordinate measurement for all layers and for all energies. A precision of a few millimeters can be achieved, which increases with energy and decreases with depth in calorimeter. A good agreement between data and simulation is found.

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Precision-Timing with Silicon Diodes

This measurement is performed on sets of 5 × 5 mm2 silicon diodes of different types (p-on-n and n-on-p) and thicknesses, previously irradiated to a range of neutron fluences representative of those expected in the HGCAL. The experimental setup, shown in Fig. 5a, consists of 3 sets of 6 diodes (2 non irradiated and 4 irradiated) interspersed with lead absorbers. The irradiated diodes were operated at 600 and 800 V, while the non-irradiated ones at 600 V only. Data were taken with electron beams of 100 and 150 GeV for p-type and n-type diodes. The pulse from each diode was digitized at 5 GHz and the pulse amplitude and timing information were extracted on an event-by-event basis, following the same procedure as in [7]. To estimate the timing capabilities of these devices, the timing measured by each diode is compared to that of an unirradiated diode of the same thickness and type. The distributions of the time differences are fitted with a Gaussian function. In Figs. 5b, c the resolution on the time difference between an unirradiated and an irradiated diode is shown for p-type, n-type diodes of 300 µm thick, as (S/N )ref (S/N )n , “ref” a function of the effective S/N, given by (S/N )ef f = √ 2 2 (S/N )ref +(S/N )n

being the reference diode and “n” the diode used for the difference. The plots show that it is possible to achieve a 20 ps timing resolution for reasonably large signals and that there is no degradation in performance at different fluences.

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Fig. 5. (a) Layout of the experimental setup for precision-timing measurement of irradiated and unirradiated diodes. (b), (c) Resolution on the time difference between an unirradiated and an irradiated diode as a function of (S/N )ef f , shown for the 300 µm thick diodes of p-type (b) and n-type (c). From CMS-CR-2017-169. Published with permission by CERN.

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Summary and Outlook

The HGCAL is the CMS subdetector chosen for replacing its current endcap in the High-Luminosity era. A proof of concept of this new calorimeter has been obtained through the construction and first beam-tests in 2016 of the siliconabsorber modules that form the basis of the electromagnetic section of the HGCAL calorimeter and the beam-test with diodes. The measurements show that it is possible to achieve a relative energy and a position resolution below ∼7% and ∼2 mm, for electrons with energy greater than 50 GeV, and a timing resolution of ∼20 ps for different radiation levels and at modest values of (S/N )ef f . The comparison with the simulation shows a good agreement of the measurement with respect to the data, giving credence to its accuracy and scalability. In 2017, the beam-tests plan foresees the study of silicon modules with an updated front-end chip (“Skiroc2-CMS” [1]) with the capability to process time information and including a configuration that can be representative of the hadronic sections of HGCAL as well.

References 1. Cokoc, S., Dulucqa, D., de La Taillea, F., Rauxa, C., Sculacc, L., Borg, T., Calliera, J., Thienpon, D.: SKIROC2 CMS an ASIC for testing CMS HGCAL. J. Instrum. 12(02), C02019 (2017) 2. Callier, S., Dulucq, F., de La Taille, C., Martin-Chassard, G., Seguin-Moreau, N.: SKIROC2, front end chip designed to readout the electromagnetic CALorimeter at the ILC. J. Instrum. 6(12), C12040 (2011) 3. CMS Collaboration The CMS experiment at the CERN LHC. JINST 3, S08004 (2008) 4. The CALICE collaboration: Construction and commissioning of the CALICE analog hadron calorimeter prototype. JINST 5, P05004 (2010) 5. Contardo, D., Klute, M., Mans, J., Silvestris, L., Butler, J.: Technical Proposal for the Phase-II Upgrade of the CMS Detector. Technical report CERN-LHCC-2015010. LHCC-P-008. CMS-TDR-15-02, Geneva, June 2015 6. GEANT4 Collaboration: Geant4 - a simulation toolkit. Nucl. Instrum. Meth. A 506, 250 (2003) 7. Akchurin, N., et al.: On the timing performance of thin planar silicon sensors. Submitted to Nuclear Instruments and Methods (2016)

Precision Timing Detectors with Cadmium Telluride Sensors Adi Bornheim(B) , Jiajing Mao, Aashrita Mangu, Cristian Pena, Maria Spiropulu, Si Xie, and Zhicai Zhang Caltech, E. California Blvd., Pasadena, CA 91125, USA [email protected]

Abstract. Precision timing detectors for high energy physics experiments with temporal resolutions of a few 10 ps are of pivotal importance to master the challenges posed by the highest energy particle accelerators. Calorimetric timing measurements have been a focus of recent research, enabled by exploiting the temporal coherence of electromagnetic showers. Scintillating crystals with high light yield as well as silicon sensors are viable sensitive materials for sampling calorimeters. Silicon sensors have very high efficiency for charged particles. However, their sensitivity to photons, which comprise a large fraction of the electromagnetic shower, is limited. A large fraction of the energy in an electromagnetic shower is carried by photons. To enhance the efficiency of detecting photons, materials with higher atomic numbers than silicon are preferable. In this paper we present test beam measurements with a Cadmium-Telluride sensor as the active element of a secondary emission calorimeter with focus on the timing performance of the detector. A Schottky type Cadmium-Telluride sensor with an active area of 1 cm2 and a thickness of 1 mm is used in an arrangement with tungsten and lead absorbers. Measurements are performed with electron beams in the energy range from 2 GeV to 200 GeV. A timing resolution of 20 ps is achieved under the best conditions. Keywords: Picosecond timing Radiation detection

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Introduction

Precision timing detectors for high energy physics experiments with temporal resolutions of a few 10 ps are of pivotal importance to master the challenges posed by the highest energy particle accelerators [1]. Calorimetric timing measurements have been a focus of recent research, enabled by exploiting the temporal coherence of electromagnetic showers [2]. In this paper, we present results of studies of a calorimeter prototype using Cadmium-Telluride (CdTe) sensors as the active material. CdTe has been studied extensively in the context of thin film solar cells and has become a mature c Springer Nature Singapore Pte Ltd. 2018  Z.-A. Liu (Ed.): TIPP 2017, SPPHY 213, pp. 56–60, 2018. https://doi.org/10.1007/978-981-13-1316-5_10

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and wide-spread technology. It has also been used as a radiation detector for nuclear spectroscopy, and is known to have high quantum efficiency for photons in the x-ray range of the spectrum. This feature is of particular interest in the context of its use in calorimetry because it would be sensitive to secondary particles in the keV range, a significant component of the electromagnetic shower. Therefore, the first study of electromagnetic showers using CdTe sensors has the potential to yield new insight into the behavior of secondary particles produced within an electromagnetic shower with energies in the keV range, and has the potential to yield an improvement on the energy measurement due to the additional contribution of the higher energy x-ray photons to which previous calorimeters were not sensitive. The recent interest on precision timing has resulted in new studies of the timing properties of silicon sensors. These studies have found a time resolution at 20 ps level, provided a sufficiently large signal size in a variety of applications ranging from calorimetry to charged particle detectors [3]. The signal formation process in CdTe sensors are very similar to the process in silicon and has similar potential to yield precise timestamps. In this article, we study the signal response of the CdTe sensor to electromagnetic showers of varying energies and at different shower depths. We also study the timing performance of the CdTe sensors for electromagnetic showers.

2

Setup

Our measurements were conducted with a CdTe Schottky type diode purchased from Acrorad [4]. It is 1 cm2 in transverse size and 1 mm thick. It was operated at a bias voltage of 700 V and the dark current was between 3 nA and 6 nA depending on the environmental conditions in the test beam experimental zones. The sensor was placed in a box made of 0.3 mm copper sheets sealed with copper tape to shield against environmental noise. A broadband amplifier with a bandwidth of 1.5 GHz was used to amplify the signals from the sensor. We performed the measurements at the H2 beamline of the CERN North-Area testbeam facility and the T9 beamline of the CERN East-Area testbeam facility. They provide secondary electron beams from the Proton Synchrotron (PS) and Super Proton Synchrotron (SPS) of energies ranging from 2 GeV to 200 GeV. The DAQ system uses a CAEN V1742 switched capacitor digitizer based on the DRS4 chip. Wire chambers are used to measure the position of each incident beam particle in the plane transverse to the beamline. A micro-channel plate photomultiplier (MCP-PMT) detector is used to provide a very precise reference timestamp. The precision of the time measurement for both types of MCP-PMTs is less than 10 ps. Further details on the experimental setup can be found in [5].

3

Experimental Results

In Fig. 1 we show the pulse shape of the CdTe sensor exposed to a shower of a 100 GeV electron induced in 6 X0 of tungsten. The pulse features an initial

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Fig. 1. Pulse shape of the CdTe sensor exposed to a shower of a 100 GeV electron induced in 6 X0 of tungsten. The pulse features an initial fast pulse with a rise time of about 1.3 ns and width of less than 10 ns, superimposed by a longer pulse with a length of order 100 ns at about 10% or the amplitude.

Fig. 2. Amplitude response of the CdTe sensor for different beam energies. The figure to the left shows the amplitude response for electrons of beam energies of 2 to 7 GeV impinging on an absorber of 2 X0 lead. The picture to the right shows the amplitude response for electrons with a beam energy of 50 to 200 GeV impinging on an absorber of 6 X0 of tungsten.

fast pulse with a rise time of about 1.3 ns and width of less than 10 ns, superimposed by a longer pulse with a length of order 100 ns at about 10% or the amplitude. Further studies are ongoing to understand if the two components can be attributed to the electron and hole charge carrier velocity which are know to be quite different in this material. The signal to noise in this data set is exceeding 100. In Fig. 2 we show the amplitude response of the CdTe when exposed to the shower induced by electrons with energies between 2 GeV to 200 GeV impinging on a absorbers of 2 X0 of lead or 6 X0 of tungsten respectively. We find a good linearity of the signal which the beam energy, considering that the shower containment is limited and the location of the sensor with respect to the shower max varies for the different beam energies. In Fig. 3 we show the timing resolution of the CdTe sensor measured with the 100 GeV electron beam. The timing measurement is extracted from a fit to the leading edge of the pulse shown in Fig. 1. We achieve a timing resolution of 25 ps averaging across the sensor. Closer studies of the uniformity of the timing response revealed that there is a peculiar dependency of the timing precision across the sensor, as shown in Fig. 4. The timing precision close to the positive bias voltage connection is around 20 ps and degrades to about 32 ps close to the ground connection. A closer study of field and charge collection homogeneity inside the sensor will have to be carried out to understand the details of the signal generation and its impact on the timing performance.

Precision Timing Detectors with Cadmium Telluride Sensors

Fig. 3. Timing resolution as measured with the CdTe sensor for electromagnetic showers induced by 100 GeV electrons on a 6 X 0 tungsten absorber. A timing resolution of about 25 ps is achieved averaging over the sensor area.

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Fig. 4. Timing resolution of the CdTe sensor as a function of the impact point on a line connecting the two corners of the sensor between the anode and the cathode side connection. The timing resolution varies between around 20 ps and 30 ps depending on the impact point.

Summary

In this paper we studied CdTe sensors as active elements in a precision timing calorimeter. We have measured the rise time for signals in the Schottky type CdTe sensor diode to be about 1.3 ns which makes them suitable as devices for precision timing applications. The large ionization signal yield we achieve with a 1 mm thick sensor, resulting in a very good signal to noise, is equally favorable for precision timing applications. We observe dependencies of the measured time on the geometric position of the beam particle impact point on the sensor, which may indicate inhomogeneities in the charge collection dynamics. More detailed studies of this aspect are needed and a more optimal design of the connection of the sensor readout is envisioned. Correcting for these dependencies yield time resolutions of 25 ps for a single layer CdTe sensor of transverse area 1 cm 1 cm, uniformly sampled by the electromagnetic shower of electrons with energy above 100 GeV after 6 radiation lengths of tungsten and lead absorber. In the most favorable region of the sensor we observe time resolutions as low as 20 ps. These initial results are encouraging and motivate further in-depth studies in the future.

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References 1. Bornheim, A., et al.: On the usage of precision timing detectors in high rate and high pileup environments. PoS (Vertex2016) 044 (2016) 2. Bornheim, A., et al.: Precision timing calorimetry for high energy physics. NIM-A. https://doi.org/10.1016/j.nima.2015.11.129 3. Apresyan, A., et al.: Test beam studies of silicon timing for use in calorimetry. NIM-A. https://doi.org/10.1016/j.nima.2016.04.031 4. Acrorad Co., Ltd. http://www.acrorad.co.jp/ 5. Bornheim, A., Pena, C., Spiropulu, M., Xie, S., Zhang, Z.: Precision timing detectors with cadmium-telluride sensor. https://doi.org/10.1016/j.nima.2017.04.024

Prototype Tests for a Highly Granular Scintillator-Based Hadronic Calorimeter Yong Liu(B) for the CALICE Collaboration Institut f¨ ur Physik and Cluster of Excellence PRISMA, Johannes Gutenberg-Universit¨ at Mainz, 55099 Mainz, Germany [email protected]

Abstract. Within the CALICE collaboration, several concepts for the hadronic calorimeter of a future lepton collider detector are studied. After having demonstrated the capabilities of the measurement methods in “physics prototypes”, the focus now lies on improving their implementation in “technological prototypes”, that are scalable to the full linear collider detector. The Analogue Hadronic Calorimeter (AHCAL) concept is a sampling calorimeter of tungsten or steel absorber plates and plastic scintillator tiles read out by silicon photomultipliers (SiPMs) as active components. The front-end electronics is fully integrated into the active layers of the calorimeter and is designed for minimal power consumption (i.e. power pulsing). The versatile electronics enables the prototype to be equipped with different types of scintillator tiles and SiPMs. In recent beam tests, a prototype with ∼3700 channels, equipped with several types of scintillator tiles and SiPMs, was exposed to electron, muon and hadron beams. The experience of these beam tests resulted in an optimal detector design with surface-mounted SiPMs suitable for the automated mass assembly. The proceeding will cover topics including the testbeam measurements with the AHCAL technological prototype, the improved detector design and the ongoing development of a large prototype for hadronic showers.

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Introduction

Precision physics programs at future lepton colliders impose stringent requirements on the calorimeter performance. In order to reach an unprecedented jet energy resolution. Calorimeters are required to be highly granular and compact inside the magnet coil. The CALICE collaboration has been developing highly granular options for electromagnetic and hadronic calorimeters [1]. The Analogue Hadronic Calorimeter (AHCAL), as one of the CALICE technical options, is a sampling hadron calorimeter concept based on scintillator tiles (30 × 30 × 3 mm3 ) coupled to silicon photomultipliers (SiPMs) as active components. Iron and tungsten have been used as absorber materials. A large physics prototype has been exposed to various beams and the capabilities of the AHCAL concept have been demonstrated [2]. The current focus lies on the c Springer Nature Singapore Pte Ltd. 2018  Z.-A. Liu (Ed.): TIPP 2017, SPPHY 213, pp. 61–65, 2018. https://doi.org/10.1007/978-981-13-1316-5_11

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implementation of a large technological prototype, which needs to be scalable to a full detector at a future lepton collider.

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AHCAL Beam-Test Campaigns and Highlights

An AHCAL prototype with 14 active layers (3744 channels in total) was tested using beams at CERN SPS in 2015 using a steel stack and a tungsten stack, respectively, as shown in Fig. 1. Large data sets have been collected, including muons for the detector calibration, electrons for precision electromagnetic shower studies and pions for detailed hadronic shower studies.

Fig. 1. The schematics of the AHCAL prototype at CERN SPS in 2015

The SiPM response to single photons has been obtained using the UV light generated by an on-board LED for each channel. The gain of each SiPM was extracted from the LED data, which can also monitor temperature variations. The detector was calibrated using muon beams as minimum ionising particles (MIPs). The readout electronics in the AHCAL prototype with a feature of fine timing measurements enables possibilities to study the temporal evolution of hadronic showers. The reference time (T0) signals come from trigger scintillator plates placed in front and rear of the AHCAL detector and the time of hits (T) in each active layer can be compared to T0. Preliminary results of muon data show similar distributions of the time difference T-T0 in steel and tungsten absorbers. Based on the time calibration procedure established by muon data, the timing analysis of electron and pion data is ongoing.

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AHCAL Mass Assembly

Various designs for the SiPM-tile coupling have been tried in the AHCAL prototype in the CERN beamtests. The surface-mounted design turned out to be

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the only solution which is suitable for mass assembly. In this design, a surfacemounted SiPM (SMD-SiPM), soldered on the PCB, directly couples to from top to a tile with a dome-shaped cavity. The thin package is fully accommodated inside the cavity, as shown in Fig. 2. The design was optimised by the GEANT4 full simulation to achieve a high and uniform light collection efficiency when particles pass through different positions [3]. A first proof-of-principle readout board with 144 channels using this design (SMD-HBU) was successfully built in 2014 via mass assembly using a pickand-place machine with electronics established for SMD-SiPMs and individually wrapped tiles. In 2016, six new SMD-HBUs were built using new SiPMs and an updated tile design while the mass assembly routine was fully practised (Fig. 2). With the benefit of new SiPMs, dark-count noise is reduced and inter-pixel crosstalk is dramatically suppressed. One such new SiPM was characterised at different temperatures. Figure 3 shows the crosstalk level is lower than 2% at the nominal reversed voltage. Also the uniformity of the SiPM quality, piece by piece as well as pixel by pixel within the same device, is much improved.

Fig. 2. Schematics of the surface-mounted design (top left), the first SMD-HBU (bottom left) and a moment of the automated tile assembly (right)

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AHCAL Technological Prototype

As the first step towards developing a large AHCAL technological prototype, a small prototype of 15 active layers with a single HBU per layer has been developed using high-quality SiPMs for electromagnetic shower studies. Interface boards of 15 layers have been updated. The detector interface (DIF) board have been redesigned, equipped with a modern FPGA. The power board has been improved for better power-pulsing performance and for lower heat dissipation. Meanwhile, new HBUs have been developed for the updated ASIC chips (SPIROC2E) in a new package (BGA). Preliminary LED tests show that there is no observable gain drop with a switch-on time of 60 µs in the powerpulsing mode, compared to the constantly running mode.

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Fig. 3. Measurements of dark-count rates at different thresholds with a new lowcrosstalk SiPM (left); a new steel stack with 15 active layers (right)

The small prototype was tested using electron beams at DESY for precision measurements of electromagnetic showers and for testing the power-pulsing performance. Promising performance has been achieved: all channels are working and the channel-wise SiPM gain is quite uniform. Efforts are being invested to check the performance differences between with and without power pulsing and to apply corrections to the SiPM saturation effect and temperature variations. The ultimate goal of the AHCAL technological prototype is to instrument 40 active layers with 2 × 2 HBUs per layer in a steel stack (∼1% of the barrel ILC-AHCAL) to demonstrate the scalability to build a final detector. Steady steps have been made towards the mass production and quality assurance. More than 24000 tiles have been produced via injection moulding. Dedicated test stands have been developed to check the functionalities of readout chips, to fully characterise SiPM samples and to test fully assembled HBUs.

5

Summary and Outlook

The scintillator-based hadronic calorimeter concept is being developed within the CALICE collaboration. Based on the experience from successful beam tests for several AHCAL prototypes, an optimal detector design suitable for the mass assembly has been chosen and promising performance has been achieved. In addition, procedures for the automated assembly and testing have been established. The AHCAL technological prototype is scheduled to be built within 2017. Meanwhile, there will be a beam test with a strong magnetic field in 2017. More tests by exposing the large prototype to hadron beams are expected in 2018.

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References 1. Sefkow, F., et al.: Experimental tests of particle flow calorimetry. Rev. Mod. Phys. 88, 015003 arXiv:1507.05893 2. The CALICE collaboration, Construction and commissioning of the CALICE analog hadron calorimeter prototype. JINST 5, P05004 arXiv:1003.2662 (2010) 3. Liu, Y., et al.: A design of scintillator tiles read out by surface-mounted SiPMs for a future hadron calorimeter. In: IEEE Nuclear Science Symposium and Medical Imaging Conference Rec. arXiv:1512.05900 (2014)

Design, Status and Perspective of the Mu2e Crystal Calorimeter G. Pezzullo2,8(B) , N. Atanov3,8 , V. Baranov3,8 , J. Budagov3,8 , F. Cervelli2,8 , F. Colao5,8 , E. Diociaiuti5,8 , M. Cordelli5,8 , G. Corradi5,8 , E. Dan`e5,8 , Yu. Davydov3,8 , S. Donati1,2,8 , R. Donghia5,8 , S. Di Falco2,8 , B. Echenard4,8 , L. Morescalchi2,8 , S. Giovannella5,8 , V. Glagolev3,8 , F. Grancagnolo6,8 , F. Happacher5,8 , D. Hitlin4,8 , M. Martini5,7,8 , S. Miscetti5,8 , T. Miyashita4,8 , L. Morescalchi2,8 , P. Murat7,8 , E. Pedreschi2,8 , F. Porter4,8 , F. Raffaelli2,8 , M. Ricci5,8 , A. Saputi5,8 , I. Sarra5,7,8 , F. Spinella2,8 , G. Tassielli6,8 , V. Tereshchenko3,8 , and R. Y. Zhu4,8 1

4

Department of Physics, University of Pisa, Largo B. Pontecorvo 3, Pisa, Italy 2 INFN Sezione di Pisa, Largo B. Pontecorvo 3, Pisa, Italy [email protected] 3 Joint Institute for Nuclear Research, Joliot-Curie 6, Dubna, Russia Department of Physics, California Institute of Technology, 1200 E California Blvd, Pasadena, CA, USA 5 INFN Laboratori Nazionali di Frascati, via Enrico Femri 40, Frascati, Italy 6 INFN Sezione di Lecce, Via Arnesano, 73100 Lecce, Italy 7 Fermi National Accelerator Laboratory, Main Entrance Rd, Batavia, IL, USA 8 Department of Energy, University Guglielmo Marconi, via Plinio, 44, 00193 Roma, Italy

Abstract. The Mu2e experiment at Fermilab will search for the charged lepton flavor violating process of neutrino-less μ → e coherent conversion in the field of an aluminum nucleus. Mu2e will reach a single event sensitivity of about 2.5 · 10−17 that corresponds to four orders of magnitude improvements with respect to the current best limit. The detector system consists of a straw tube tracker and a crystal calorimeter made of undoped CsI coupled with Silicon Photomultipliers. The calorimeter was designed to be operable in a harsh environment where about 10 krad/year will be delivered in the hottest region and work in presence of 1 T magnetic field. The calorimeter role is to perform μ/e separation to suppress cosmic muons mimiking the signal, while providing a high level trigger and a seeding the track search in the tracker. In this paper we present the calorimeter design and the latest R&D results.

1

Introduction

Observation of the neutrino oscillation during the last decades boosted the interest of the experimental community in the search of Lepton Flavour Violating (CLFV) processes also in the field of charged leptons. The muon conversion represents a powerful channel to search for CLFV, because it is characterized by a distinctive signal consisting in a mono-energetic electron with energy c Springer Nature Singapore Pte Ltd. 2018  Z.-A. Liu (Ed.): TIPP 2017, SPPHY 213, pp. 66–69, 2018. https://doi.org/10.1007/978-981-13-1316-5_12

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Ece = mµ −Eb −E2µ /(2mN ) , where mµ is the muon mass at rest, Eb ∼ Z2 α2 mµ /2 is the muonic atom binding energy for a nucleus with atomic number Z, Eµ is the nuclear recoil energy, Eµ = mµ −Eb , and mN is the atomic mass [1]. In case of aluminum, which is the major candidate for upcoming experiments, Ece = 104.973 MeV [2].

2

Calorimeter Design

The calorimeter consists of two disks anulii, separated by 75 cm, with ineer (outer) radius of 37.4 (66) cm. Each disk is filled wih 678 undoped CsI crystals 20 × 3.4 × 3.4 cm3 . The inner region is left un-instrumented to avoid interactions with low energy electrons, while the separation between the disks maximize the acceptance for the conversion electrons (CE). Each crystal is read out by two arrays 2 × 3 of 6 × 6 mm2 SiPM. Each SiPM array is matched to a front end electronics board (FEE) that provides an amplification stage and also local voltage regulation. Signal form the FEE is then digitized by a custom made waveform digitizer @ 200 Msps [3]. Figure 1 shows a 3D representation of the calorimeter and a picture of the crystals and SiPM from the pre-production. A more detailed description of the calorimeter design can be found on reference [4].

Fig. 1. Left: Calorimeter design. Right: Undoped CsI crystals from the pre-production and one SiPM + FEE module.

3

Role of the Calorimeter in Mu2e

The main role of the calorimeter in Mu2e is to provide particle identification capabilities that are essentials to distinguish Cosmic μ @ p = 105 MeV/c mimicking the CE. The rejection algorithm is based on a likelihood ratio that uses as input the following observables: (1) E/p: ratio of the track momentum and the calorimeter cluster energy; (2) Δt: time residual between the calorimeter cluster and the track time as extrapolated to the calorimeter. Figure 2 shows the distribution of E/p and Δt for CE and μ @ p=105 MeV/c. The calorimeter

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information are also useful for driving the track search in the tracker by means of time and spatial correlations with the hits in the chamber associated to the same particle that produced the calorimeter cluster [5]. Figure 3 shows how the hits pre-selection reduces the number of background hits in a typical event with one CE overlaid with the expected background.

Fig. 2. Left: distribution in Δt for CE and μ @ p=105 MeV/c. Right: Distribution in E/p for CE and μ @ p=105 MeV/c.

Fig. 3. Transverse view of an event display for a CE event with background hits included, with (right) and without (left) the calorimeter pre-selection. The black crosses represent the straw hits, the red bullets the calorimeter clusters, and the red circle the CE trajectory.

4

R and D

During late 2016 we started the pre-production of the crystals, SiPM and FEE boards that were used for the assembly of the final calorimeter prototype, see Fig. 4. This prototype has a key role in validating the expected physics performance and also check several mechanical properties, like the performance of the cooling system and the assembly procedures. During May 2017 a test beam was performed at the Beam Test Facility in Frascati (Italy) [6] using an e− beam in the range [60, 120] MeV.

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Fig. 4. Calorimeter prototype during the assembly phase.

5

Summary

In this paper the calorimeter project for the Mu2e experiment has been presented. We showed that the Mu2e calorimeter design is able to provide particle identification capabilities, an high level trigger and is also a helpfull tool for improving the tracking pattern recognition. A test beam with a prototype of the calorimeter was performed during May 2017 using an electron beam in the energy range [60, 120] MeV. Acknowledgment. This work was supported by the US Department of Energy; the Italian Istituto Nazionale di Fisica Nucleare; the US National Science Foundation; the Ministry of Education and Science of the Russian Federation; the Thousand Talents Plan of China; the Helmholtz Association of Germany; and the EU Horizon 2020 Research and Innovation Program under the Marie Sklodowska-Curie Grant Agreement No.690385.

References 1. Marciano, W.J., et al.: Charged lepton flavor violation experiments. Ann. Rev. Nucl. Part. Sci. 58(1), 315–341 (2008) 2. Kitano, R., et al.: Detailed calculation of lepton flavor violating muon electron conversion rate for various nuclei. Phys. Rev. D 66(9), 096002 (2002) 3. Di Falco, S., et al.: Components qualification for a possible use in the Mu2e calorimeter waveform digitizer. JINST 12(03), C03088 (2017) 4. Mu2e Calorimeter group, The Mu2e Calorimeter Final Technical Design Report. http://mu2e-docdb.fnal.gov/cgi-bin/ShowDocument?docid=8429 5. Pezzullo, G., Murat, P.: The calorimeter-seeded track reconstruction for the Mu2e experiment at Fermilab. In: Proceedings of 2015 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC), pp. 1–3 (2015) 6. Mazzitelli, G., et al.: Commissioning of the DAφNE beam test facility. NIM A 515(3), 524–542 (2003)

Applications of Very Fast Inorganic Crystal Scintillators in Future HEP Experiments Ren-Yuan Zhu(&) California Institute of Technology, Pasadena, CA 91125, USA [email protected] Abstract. Future HEP experiments at the energy and intensity frontiers require fast inorganic crystal scintillators with excellent radiation hardness to face the challenges of unprecedented event rate and severe radiation environment. This paper reports recent progress in application of fast inorganic scintillators in future HEP experiments, such as thin layer of LYSO crystals for a shashlik sampling calorimeter and a precision TOF detector proposed for the CMS upgrade at HL-LHC, undoped CsI crystals for the Mu2e experiment at Fermilab and yttrium doped BaF2 crystals for Mu2e-II. Applications of very fast crystal scintillators for Gigahertz hard X-ray imaging for the proposed Marie project at LANL will also be discussed. Keywords: Inorganic scintillators


Crystals
Radiation hardness

1 Introduction Fast and radiation hard inorganic crystal scintillators are needed for future HEP experiments at the energy and intensity frontiers. For experiments to be operated at HLLHC with 3000 fb−1, for example, crystals should survive an environment with absorbed dose of 100 Mrad, charged hadron fluence of 6  1014 cm−2 and fast neutron fluence of 3  1015 cm−2. For future HEP experiments at the intensity frontier, such as Mu2e-II, ultra-fast crystals are needed to face the challenge of unprecedented event rate as well as severe radiation. Table 1 lists basic properties of crystals commonly used in HEP experiments, where experiment names in brackets were proposed but not constructed. Among the crystals listed in Table 1, bright, fast and radiation hard lutetium yttrium oxyorthosilicate (Lu2(1−x)Y2xSiO5:Ce or LYSO) crystals were proposed for a LYSO/W/Quartz capillary sampling calorimeter [1] and a precision time of flight (TOF) layer for the CMS upgrade for the HL-LHC [2]. Undoped CsI crystals are used to construct a calorimeter for the Mu2e experiment at Fermilab [3]. BaF2 crystals have a unique fast scintillation light with sub-ns decay time, but also a slow scintillation light component with 600 ns decay time. Recently developed yttrium doped BaF2 crystals with effective slow component suppression have a great potential for an extra fast calorimeter for Mu2e-II. They may also be used in the proposed MaRIE facility [4], where unprecedented X-ray fluxes requires ultra-fast X-ray imaging [5].

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Table 1. Inorganic crystals commonly used in HEP experiments

2 Time Resolution of Crystal Scintillators Crystal time resolution depends on the signal to noise ratio for the rise time measurement. While the intrinsic rising time of most crystals is as fast as a few tens ps [6], Fig. 1 shows the rising time measured for ten crystal samples of 1.5X0 size by using a Hamamatsu R2059 PMT. The fast rise time of about 1.5 and 1.6 ns observed respectively for BaF2 and LYSO is limited by the PMT rise time 1.3 ns (2500 V) and the rise time of 0.14 ns of the Agilent MSO9254A (2.5 GHz) DSO. The measured rise time is also faster for the same crystal with a black wrapping, where the light propagation in crystal is minimized [7]. Table 2 lists the figure of merit values on time resolution for various crystal detectors, which is defined as the light output in the 1st, or the 1st 0.1, ns [7]. It is clear that the best crystal scintillators for ultra-fast timing are BaF2, LSO:Ca,Ce and LYSO: Ce. LaBr3 is a material with high potential theoretically, but suffers from scattering centers in the crystal as well as its intrinsic hygroscopicity.

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Fig. 1.

Scintillation rising time measured for ten crystal samples of 1.5 X0

Table 2. Figure of merit for time resolution for various crystal scintillators

3 Quality of Preproduction CsI Crystals for Mu2e The Mu2e experiment at Fermilab is constructing a fast calorimeter using undoped CsI crystals. 72 preproduction CsI crystals from three vendors were characterized. Figure 2 compares data with the Mu2e specifications (red dashed lines), showing that most crystals meet the specifications on light output, FWHM energy resolution, light response uniformity, F/T (Fast/Total) ratio, c-ray induced noise and radiation hardness. Some crystals failed specifications on F/T ratio and c-ray induced noise because of significant slow scintillation component. Excellent correlations have been observed between the light output and the energy resolution, and the dark current, the c-ray induced readout noise and the F/T ratio, confirming that they are of the same origin [8].

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Fig. 2.

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Quality of preproduction undoped CsI crystals of 3.4  3.4  20 cm

4 Yttrium Doped BaF2 Crystals BaF2 crystal has a very fast scintillation component peaked at 220 nm with sub-ns decay time, which provides a solid foundation for a very fast calorimetry. It, however, has also a slow scintillation component peaked at 300 nm with 600 ns decay time and a five times brightness of its fast component, which would cause pileup. Two approaches are used to reduce the pileup caused by slow component: selective doping with rare earth (La, Y, and Ce) in BaF2 and selective readout with solar blind photodetector [9]. Figure 3 shows a set of yttrium doped BaF2 crystal samples of U18  21 mm doped with yttrium from 0 to 7 mol% from BGRI. Also shown are their spectra of X-ray excited luminescence (XEL) and transmittance, light output as a function of integration time, light output in 50 and 2,500 ns gates, and the corresponding ratios as a function of the level of yttrium doping in mol%. It was found that the optimized yttrium doping in BaF2 is about 5 mol%, which increases the F/s (Fast/Slow) ratio from 1/5 to 5/1 without selected readout while the amount of fast light is unchanged. The crystals of this nature is expected to find a broad application in future HEP experiments and GHz X-ray imaging.

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Fig. 3.

Performance of Yttrium doped BaF2 crystals of U18  21 mm

5 Summary LYSO is a robust scintillators against ionization dose as well as charged and neutral hadrons expected at the HL-LHC. Commercially available undoped CsI crystals satisfy the Mu2e requirements. Commercially available undoped BaF2 crystals provide sufficient fast light with sub-ns decay time and excellent radiation hardness beyond 100 Mrad and 1  1015 p cm−2. They promise a very fast and robust calorimeter in a severe radiation environment. Yttrium doping in BaF2 crystals increases the F/S ratio from 1/5 to 5/1 without using a selected readout, while maintaining the amount of fast scintillation light. The slow contamination at this level is already much less than commercially available undoped CsI. The novel crystals of this nature is promising a very fast calorimetry for future HEP experiments and GHz X-ray imaging. Photodetector with DUV response, e.g. a Si or diamond based photodetector [10] and the radiation hardness of yttrium doped BaF2 crystals need to be investigated. Acknowledgements. This work is supported by the U.S. Department of Energy, Office of High Energy Physics program under Award Number DE-SC0011925.

References 1. Zhang, L.Y., Mao, R.H., Yang, F., et al.: LSO/LYSO crystals for calorimeters in future HEP experiments. IEEE Trans. Nucl. Sci. 61, 483–488 (2014) 2. Tabarelli de Fatis, T.: Precision timing studies and detector concept proposal. Presentation given in the CMS general meeting, 16 November 2016

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3. Pezzullo, G.: Design, status and perspectives for the Mu2e crystal calorimeter. In: Proceedings of Matter-Radiation Interactions in Extremes (MaRIE). 4. http://www.lanl.gov/science-innovation/science-facilities/marie/index.php 5. Wang, Z., Barnes, C.W., Kapustinsky, J.S., et al.: Thin scintillators for ultrafast hard X-ray imaging. In: Proceedings of SPIE 9504, Photon Counting Applications, Paper 95040N, 6 May 2015 6. Derenzo, S.E., Weber, M.J., Moses, W.W., Dujardin, C.: Measurements of the intrinsic rise times of common inorganic scintillators. IEEE Trans. Nucl. Sci. 47, 860 (2000) 7. Zhu, R.-Y.: http://www.hep.caltech.edu/*zhu/talks/ryz_110428_time_resolution.pdf 8. Yang, F., Zhang, L.Y., Zhu, R.-Y.: Slow scintillation component and radiation induced readout noise in pure CsI crystals. Paper N07-9 in 2016 IEEE NSS conference record 9. Yang, F., Chen, J.F., Zhang, L.Y., Zhu, R.-Y.: Development of BaF2 crystals for future HEP experiments at the intensity frontiers. Paper N36-7 in 2016 IEEE NSS conference record 10. Monroy, E., Omnes, F., Calle, F.: Wide-bandgap semiconductor ultraviolet photodetectors. Semicond. Sci. Technol. 18, R33 (2003)

Liquid Xenon Detector with VUV-Sensitive MPPCs for MEG II Experiment Shinji Ogawa(&) on behalf of the MEG II Collaboration Faculty of Science, Graduate School of Science, The University of Tokyo, Tokyo 113-0033, Japan [email protected]

Abstract. The MEG II experiment is an upgrade of the MEG experiment which searched for the charged lepton flavor violating decay of muon, l!ec. The target sensitivity of MEG II experiment is 4  10−14. The liquid xenon (LXe) detector was used to detect c-ray from the signal decay, and its performance will be upgraded in MEG II. To achieve the higher granularity and uniformity of the scintillation readout, 216 photomultiplier tubes (PMTs) on the c-ray entrance face has been replaced with 4092 Multi-Pixel Photon Counters (MPPCs). In this replacement, a large area VUV-MPPC is used which was newly developed in collaboration with Hamamatsu Photonics K.K. The performance of this MPPC was measured in LXe. Photon detection efficiency for LXe scintillation light was confirmed to be over 15%. Mass production of MPPC was performed and it was successfully installed to the detector. Detector commissioning is now ongoing towards the pilot run at the end of this year. Keywords: Calorimeter

 Liquid xenon  MPPC  SiPM  VUV light

1 Liquid Xenon Detector in MEG II Experiment 1.1

MEG II Experiment

MEG experiment has searched for the charged lepton flavor violating decay of muon, l!ec. MEG experiment was carried out at Paul Scherrer Institut (PSI), where the world’s most intense DC muon beam was available. By the analysis of the MEG full dataset, upper limit of the branching ratio of l!ec decay (at 90% confidence level) has been set to 4.2  10−13 [1]. MEG II experiment is an upgrade of the MEG experiment and its target sensitivity is 4  10−14 [2]. Muon beam intensity in MEG II will be 7  107 l/s, which is twice larger than MEG. To reduce the accidental background due to the higher beam intensity, all MEG II detectors are designed to improve their resolutions by a factor of 2. 1.2

Liquid Xenon Gamma-Ray Detector in MEG II

In the MEG experiment, a 900 L liquid xenon (LXe) c-ray detector was used. The purpose of this detector is to measure the hit position, energy, and hit timing of the © Springer Nature Singapore Pte Ltd. 2018 Z.-A. Liu (Ed.): TIPP 2017, SPPHY 213, pp. 76–79, 2018. https://doi.org/10.1007/978-981-13-1316-5_14

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52.8 meV c-ray coming from l!ec decay. In the MEG II experiment, this LXe detector has been upgraded to improve its performance significantly. We have replaced 216 Photo Multiplier Tubes (PMTs) on the c-ray entrance face with 4092 Multi-Pixel Photon Counters (MPPCs). Thanks to this replacement, better uniformity and granularity of the scintillation readout (Fig. 1) will be realized.

Fig. 1. c-Ray entrance face of LXe detector. (Left) MEG experiment, (right) MEG II experiment. We have replaced 216 2-in. PMTs with 4092 12  12 mm2 MPPCs

A Monte Carlo simulation has been prepared based on the measured properties of the MPPC which is described in the Sect. 2. Estimated performance of MEG II LXe detector is summarized in the Table 1. Position and energy resolution is expected to be improved by a factor of 2. Table 1. LXe detector performance for signal c-ray. r (position) r (energy) r (timing) Efficiency

MEG (measured) *5 mm *2% 67 ps 65%

MEG II (simulated) *2.5 mm 0.7–1.5% 50–70 ps 70%

2 Development of VUV-Sensitive MPPC 2.1

Large Area VUV-Sensitive MPPC

There are several requirements for the MPPC used in the MEG II LXe detector. At first it has to be sensitive to the LXe scintillation light in vacuum ultraviolet (VUV) range (k = 175 nm [3]). In addition to that, the sensitive area per one readout channel has to be sufficiently large (12  12 mm2) to keep the number of channels manageable. Since there was no MPPC which meets these requirements, a new MPPC has been developed in collaboration with Hamamatsu Photonics K.K (Fig. 2) [4]. This is a discrete array of four 6  6 mm2 MPPC chips whose pixel pitch is 50 lm. The sensor

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chips are covered by a VUV-transparent quartz window for protection. LXe can be entered between sensor chip and quartz window, not to lose the light by a reflection.

Fig. 2. (Left) Large area VUV-sensitive MPPC

Fig. 3. (Right) Setup for the MPPC performance measurement

The PDE of the commercial MPPC for VUV light was almost zero due to the absorption before reaching to the sensitive region. In our MPPC, sensitivity to VUV light is achieved by removing the protection layer of resin, optimizing the optical matching between LXe and the sensor surface, and thinning the contact layer. Four sensor chips on a same package are connected in series in the readout PCB to reduce the large sensor capacitance due to large sensitive area per channel. 2.2

Performance of Our MPPC

Performance of our MPPC has been measured in LXe by using a setup shown in Fig. 3. Waveform without segmentation (equivalent to 12  12 mm2 MPPC) and that with series connection of four 6  6 mm2 chips have been compared (Fig. 4). Time constant has been reduced with series connection, and sufficiently short time constant has been achieved. Crosstalk and after pulse probabilities have been measured to be only 15% for each at 7 V over voltage.

Fig. 4. (Left) MPPC waveform with normal connection and series connection

Fig. 5. (Right) PDE for xenon scintillation light (as a function of over voltage)

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Photon detection efficiency (PDE) for xenon scintillation light has been measured. It is defined as a ratio of the detected number of photoelectrons to the expected number of impinging photons. Effect of the correlated noises have been corrected. PDE over 15% was confirmed as shown in Fig. 5.

3 Detector Construction 3.1

Mass Production and Mass Test of MPPC

Mass production of 4200 MPPCs finished in October 2015, and all of them have been tested at room temperature to reject bad chips. By measuring the I–V curves and waveforms from LED light of each chips, most of the sensors are confirmed to be OK. The fraction of the bad chips was only 0.2%. 3.2

Detector Assembly

After the mass test, MPPCs have been installed into the cryostat. Installation has been done by mounting MPPCs on PCB, which is fixed to the cryostat. These PCBs are used both for the signal readout and the alignment of MPPCs. Position of the MPPCs have been measured by 3D Laser scanner. Installation of other materials, such as PMTs, cables, and calibration sources have also been finished. Detector has been installed to the experiment area. Detector commissioning is now ongoing towards the pilot run under the nominal MEG II beam condition at the end of this year.

4 Summary MEG II experiment will search for l!ec decay with the sensitivity of 4  10−14, and upgraded LXe detector will play an important role for this sensitivity improvement. For this purpose, large area VUV-sensitive MPPC has been successfully developed, and its excellent performance has been confirmed in our test. Detector assembly has been finished, and detector commissioning is ongoing towards the pilot run under the nominal MEG II beam condition at the end of this year. Acknowledgements. This work was supported by Grant-in-Aid for JSPS fellows, and JSPS KAKENHI Grant Numbers 22000004 and 26000004.

References 1. Baldini, A.M., et al.: Search for the lepton flavour violating decay l+!e+c with the full dataset of the MEG experiment. Eur. Phys. J. C 76, 434 (2016) 2. Baldini, A.M., Mori, T., et al.: MEG upgrade proposal. arXiv:1301.7225 3. Fujii, K., et al.: High-accuracy measurement of the emission spectrum of liquid xenon in the vacuum ultraviolet region. Nucl. Instrum. Methods A 795, 293 (2015) 4. Ootani, W., et al.: Development of deep-UV sensitive MPPC for liquid xenon scintillation detector. Nucl. Instrum. Methods A 787, 220 (2015)

Electromagnetic Calorimeter Prototype for the SoLID Project at Jefferson Lab Y. Tian1 , J.-P. Chen2 , C. Feng1(B) , J. Jiao1 , A. Li1 , Y. Yu1 , and X. Zheng3 1

2

Shandong University, Jinan 250100, China [email protected] Thomas Jefferson National Accelerator Facility, Newport News, VA 23606, USA 3 University of Virginia, Charlottesville, VA 22904, USA

Abstract. SoLID (Solenoidal Large Intensity Device) is a large acceptance spectrometer which can handle very high luminosity, being planned for experimental Hall A at Jefferson Lab, USA. The shashlik-type sampling detector will be used for the electromagnetic calorimeter for SoLID. This calorimeter is 18 radiation-lengths long with 194 layers each of 1.5 mm-thick plastic scintillators alternating with 0.5 mm-thick lead plates. A few prototype of the calorimeter have been built at Shandong University. The light yield of these modules have been tested with cosmic ray. The assembling process of these prototypes and cosmic ray test results are presented. Keywords: SoLID · Electromagnetic calorimeter Shashlik calorimeter

1

Introduction

To fully exploit the potential of the Jlab 12 GeV energy upgrade, a large acceptance spectrometer known as SoLID (Solenoidal Large Intensity Device) [1], which can handle very high luminosity, is being planed in Hall A at Jefferson Lab. As shown in Fig. 1, SoLID project includes two configurations: the SIDIS (Semi-Inclusive Deep Inelastic Scattering) and the PVDIS (Parity-Violating Deep Inelastic Scattering), which have different geometrical layouts but similar detectors. SoLID Electromagnetic Calorimeter (EC) will be used in both PVDIS and SIDIS configurations to separate electron from pions and other hadrons by measuring their energy deposition. Special challenges due to high background and high magnetic field must be considered in the EC design. The desired performance of SoLID EC is illustrated in Table 1. A shashlik style [2] sampling EC is designed to meet the needs of both configurations. The Shashlik calorimeter is based on a technique to readout the scintillation light of multi-layer lead/scintillator plate sampling calorimeter with the use of WLS (Wave-Length Shifting) fibers running perpendicular to the plates through holes in the plates. It has been applied in several particle and c Springer Nature Singapore Pte Ltd. 2018  Z.-A. Liu (Ed.): TIPP 2017, SPPHY 213, pp. 80–85, 2018. https://doi.org/10.1007/978-981-13-1316-5_15

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Fig. 1. Two configurations of the SoLID detector layout. The detectors in blue are the Electromagnetic Calorimeters. Table 1. SoLID EC desired performance. Specification

Desired performance

π−

50–100:1

−

e

Energy resolution

>90–95% √ less than 10%/ E(GeV)

Timing resolution

100∼500 ps

efficiency

Radiation resistance >500 kRad Position resolution