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1. chinaXiv:201609.00914 [pdf]

Aging effect in the BESIII drift chamber

DONG Ming-Yi; XIU Qing-Lei; WU Ling-Hui; WU Zhi; QIN Zhong-Hua; SHEN Pin; AN Fen-Fen; JU Xu-Dong; LIU Yi; ZHU Kai; OU-YANG Qun; CHEN Yuan-Bo
Subjects: Physics >> Nuclear Physics

As the main tracking detector of BESIII, the drift chamber works for accurate measurements of the tracking and the momentum of the charged particles decayed from the reaction of BEPCII e+ and e-. After operation six years, the drift chamber is suffering from aging problems due to huge beam related background. The gains of the cells in the first ten layers experience an obvious decrease, reaching a maximum of about 29% for the first layer cells. Two calculation methods for the gains change (Bhabha events and accumulated charges with 0.3% aging ratio for inner chamber cells) get almost the same results. For the Malter effect encountered by the inner drift chamber in Jan., 2012, about 0.2% water vapor was added to MDC gas mixture to solve this cathode aging problem. These results provide an important reference for MDC operation high voltage setting and the upgrade of the inner drift chamber.

submitted time 2016-09-13 Hits786Downloads430 Comment 0

2. chinaXiv:201609.00908 [pdf]

Evaluation of new large area PMT with high quantum efficiency

LEI Xiang-Cui; HENG Yue-Kun; QIAN Sen; XIA Jing-Kai; LIU Shu-Lin; WU Zhi; YAN Bao-Jun; XU Mei-Hang; WANG Zheng LI Xiao-Nan; RUAN Xiang-Dong; Wang Xiao-Zhuang; YANG Yu-Zhen; WANG Wen-Wen; FANG Can; LUO Feng-Jiao; LIANG Jing-Jing 1,4 YANG Lu-Ping 1,7 YANG Biao 1,2
Subjects: Physics >> Nuclear Physics

The neutrino detector of the Jiangmen Underground Neutrino Observatory (JUNO) is designed to use 20 kilotons of liquid scintillator and approximately 16,000 20-inch photomultipliers (PMTs).One of the options is to use the 20-inch R12860 PMT with high quantum efficiency which has recently been developed by Hamamatsu Photonics. The performance of the newly developed PMT preproduction samples is evaluated. The results show that its quantum efficiency is?0%燼t?00nm. Its Peak/Valley (P/V) ratio for the single photoelectron is 4.75 and the dark count rate is?7kHz燼t the threshold of 3 mV while the gain is at??07. The transit time spread of a single photoelectron is2.86ns. Generally the performances of this new 20-inch PMT are improved over the old one of R3600.

submitted time 2016-09-13 Hits744Downloads433 Comment 0

3. chinaXiv:201609.00002 [pdf]

The test of the electronics system for the BESIII ETOF upgrade

WANG Xiao-Zhuang; DAI Hong-Liang; WU Zhi; HENG Yue-Kun; Zhang Jie; CAO Ping; JI Xiao-Lu; Li Cheng; SUN Wei-Jia; WANG Si-Yu; WANG Yun
Subjects: Physics >> Nuclear Physics

It is proposed to upgrade the endcap time-of-flight (ETOF) of the Beijing Spectrometer III (BESIII) with multi-gap resistive plate chamber (MRPC), aiming at overall time resolution about 80 ps. After the entire electronics system is ready, some experiments, such as heat radiating, irradiation hardness and large-current beam tests,are carried out to certify the electronics' reliability and stability. The on-detector test of the electronics is also performed with the beam at BEPCII E3 line, the test results indicate that the electronics system fulfills its design requirements.

submitted time 2016-09-01 Hits1004Downloads503 Comment 0

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