Commissioning of the electron identification system for Dilepton measurement in pA collisions at J-PARC
Commissioning of the electron identification system for Dilepton measurement in pA collisions at J-PARC
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J-PARC 调试用于 pA 碰撞中双轻子测量的电子识别系统
DOI：
10.1016/j.nima.2022.167335
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发表时间：
2022
期刊：
影响因子：
--
通讯作者：
et al.,
中科院分区：
文献类型：
--
作者：
S. Nakasuga;M. Ichikawa;M. Naruki;H. Sako;S. Sato;et al.,
由于手征对称性的部分恢复，强子质谱有望在核物质中被修改。我们利用J-PARC E16实验测量了核中矢量介子的光谱修正。我们检测到的电子-正电子对衰变的介子，产生在30 GeV的pA反应。从巨大的强子背景中分离出电子是我们实验的关键。为了识别电子，我们开发了两级探测器，包括强子盲探测器（HBD）和铅玻璃电磁量能器（LGs）。这些探测器于2020年建造并安装在J-PARC高动量光束线上，并于2020年和2021年进行了调试运行。HBDs和LG在10 MHz pA靶相互作用中产生的高计数率下稳定运行，并成功检测到电子。初步结果表明，在工作阈值下，HBD和LG的π介子抑制率分别为97.6±0.6%和91.2±0.7%，与设计性能一致。电子效率的进一步评估正在进行中。
Hadron mass spectra are expected to be modified in nuclear matter due to a partial restoration of chiral symmetry. We perform the J-PARC E16 experiment to measure the spectral modification of vector mesons in nuclei. We detect electron–positron pairs from decays of ϕ mesons, produced in 30 GeV pA reactions. It is a key for our experiment to separate electrons from huge hadronic backgrounds. To identify electrons, we developed two-stage detectors comprising hadron blind detectors (HBDs) and lead-glass electromagnetic calorimeters (LGs). These detectors were constructed and installed at the J-PARC high-momentum beamline in 2020, and commissioning runs were performed in 2020 and 2021. The HBDs and the LGs were stably operated at a high counting rate generated in 10-MHz pA interaction at targets, and successfully detected electrons. In the preliminary results, the pion rejection powers were found to be 97.6±0.6% and 91.2±0.7% for the HBD and LG, respectively, which are consistent with the design performance, at the operation thresholds. Further evaluation of electron efficiency is ongoing.