Subjects: Physics >> Nuclear Physics submitted time 2016-09-13
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
Abstract： 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.
Peer Review Status:
Awaiting Review
Subjects: Physics >> Nuclear Physics submitted time 2016-09-13
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
Abstract： 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.
Peer Review Status:Awaiting Review
Subjects: Physics >> Nuclear Physics submitted time 2016-09-01
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
Abstract： 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.
Peer Review Status:Awaiting Review
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