Upgrade of ASACUSA’s antihydrogen detector
Upgrade of ASACUSA’s antihydrogen detector
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ASACUSA反氢探测器升级
DOI：
10.1016/j.nima.2022.167568
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发表时间：
2023
期刊：
影响因子：
--
通讯作者：
et al.
中科院分区：
文献类型：
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作者：
Kraxberger V.;et al.
欧洲核子研究中心反质子减速器上的ASACUSA（Atomic Spectroscopy And Collisions Using Slow Antiproton）CUSP实验的目的是测量反氢原子的基态超精细分裂，以检验CPT不变性是否被破坏。ASACUSA hodoscope是一个探测器，由两层32个塑料闪烁体组成，每层两端分别由两个串联的硅光电倍增管（SiPM）读出。用于沿着射束轴的位置分辨率的两个附加层是闪烁体纤维，其现在将被放置在现有条上的闪烁瓦片所取代，并且也由SiPM读出。如果反氢原子的反质子在速度计的中心湮灭，就会产生粒子（主要是π介子），它们会穿过探测器的各个层并产生信号。速度计在欧洲核子研究中心的最后一次数据采集期间得到了成功的使用。通过使用波形数字化器和软件常数分数鉴别，实现了区分从外部穿过检测器的颗粒和在检测器中心产生的颗粒所需的时间分辨率。这种读出方案的缺点是读出速度慢，提高了两个数量级。这是通过省略数字转换器并将其替换为使用前沿鉴别阅读数字超阈值时间（ToT）信号的TDC来实现的。
The goal of the ASACUSA (Atomic Spectroscopy And Collisions Using Slow Antiprotons) CUSP experiment at CERN’s Antiproton Decelerator is to measure the ground state hyperfine splitting of antihydrogen in order to test whether CPT invariance is broken.The ASACUSA hodoscope is a detector consisting of two layers of 32 plastic scintillator bars individually read out by two serially connected silicon photomultipliers (SiPMs) on each end. Two additional layers for position resolution along the beam axis were scintillator fibres, which will now be replaced by scintillating tiles placed onto the existing bars and also read out by SiPMs. If the antiproton of antihydrogen annihilates in the centre of the hodoscope, particles (mostly pions) are produced and travel through the various layers of the detector and produce signals.The hodoscope was successfully used during the last data taking period at CERN. The necessary time resolution to discriminate between particles travelling through the detector from outside and particles produced in the centre of the detector was achieved by the use of waveform digitisers and software constant fraction discrimination. The disadvantage of this readout scheme was the slow readout speed, which was improved by two orders of magnitude. This was done by omitting the digitisers and replacing them with TDCs reading out the digital time-over-threshold (ToT) signal using leading edge discrimination.