29 July 2018 to 4 August 2018
Russian Academy of Sciences
Europe/Moscow timezone

Performance and commissioning of HAPDs in the Aerogel RICH counter

31 Jul 2018, 12:15
25m
Russian Academy of Sciences

Russian Academy of Sciences

Leninsky Prospekt, 32а Moscow 119071 Russian Federation
oral presentation [20+5 min] Photon detection for Cherenkov counters Photon detection for Cherenkov counters

Speaker

Masanobu Yonenaga (Tokyo Metropolitan University)

Description

The Aerogel Ring Imaging Cherenkov (ARICH) counter is a particle identification device located in the endcap region of the Belle II detector. The main components of the ARICH counter are 248 silica aerogel tiles built into the Cherenkov radiator and 420 Hybrid Avalanche Photo Detectors (HAPDs) making up the photon detector. Angular distribution of Cherenkov photons emitted from silica aerogel and detected by HAPDs is used to identify charged particles. Therefore, HAPD performance is essential for the ARICH counter.
The HAPD is a vacuum tube made of ceramic body, quartz window with semitransparent photocathode and 4 segmented Avalanche Photo Diode (APD) chips. APD chips consist of 36 pixels covering $4.9 \times 4.9\, mm^2$ each. Multiplication in an HAPD is a combination of impact ionization of a photo-electron accelerated by the high voltage applied between photocathode and APD, bombardment gain, and APD avalanche process, avalanche gain.
All the HAPDs were tested before the installation into ARICH detector. One of the issues of HAPDs is a very large signal observed when operated inside the magnetic field therefore each HAPD was also tested in the magnetic field. Final results of the tests before the installation will be reported.
Installation of HAPDs to the ARICH detector finished in July 2017, and the ARICH was installed in the Belle II detector at the end of 2017. The commissioning of the ARICH counter was performed in the spring 2018 with cosmic rays and beam collision events. Although all HAPDs passed several tests before the assembly, few of them suffered issues as frequent large signals and inability to apply bias voltage properly. The behavior of these HAPDs will also be discussed. Performance of HAPDs based on the number of detected Cherenkov photons and Cherenkov angle distributions was evaluated and the results will be reported.

Primary author

Masanobu Yonenaga (Tokyo Metropolitan University)

Co-authors

Ichiro Adachi (High Energy Accelerator Research Organization (KEK), Graduate University of Advanced Science (SOKENDAI)) Leonid Burmsistrov (Laboratoire de Laccelerateur Lineaire (LAL)) Francois Le Diberder (Laboratoire de Laccelerateur Lineaire (LAL)) Shiori Kakimoto (Tokyo Metropolitan University) Hidekazu Kakuno (Tokyo Metropolitan University) Hideyuki Kawai (Chiba University) Takeo Kawasaki (Kitasato University) Haruki Kindo (Graduate University of Advanced Science (SOKENDAI)) Tomoyuki Konno (Kitasato University) Samo Korpar (University of Maribor, Jozef Stefan Institute) Peter Krizan (University of Ljubljana, Jozef Stefan Institute) Tetsuro Kumita (Tokyo Metropolitan University) Yun-Tsung Lai (High Energy Accelerator Research Organization (KEK)) Masahiro Machida (Tokyo University of Science) Manca Mrvar (Jozef Stefan Institute) Shohei Nishida (High Energy Accelerator Research Organization (KEK), Graduate University of Advanced Science (SOKENDAI)) Kouta Noguchi (Tokyo Metropolitan University) Kazuya Ogawa (Niigata University) Satoru Ogawa (Toho University) Rok Pestotnik (Jozef Stefan Institute) Luka Santelj (Hubert Curien Multi-disciplinary Institute (IPHC)) Makoto Tabata (Chiba University) Takayuki Sumiyoshi (Tokyo Metropolitan University) Sachi Tamechika (Tokyo Metropolitan University) Morihito Yoshizawa (Niigata University) Yosuke Yusa (Niigata University)

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