Development of water Čerenkov detector for on-line proton rejection in hypernuclear spectroscopy via the () reaction

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• 作者：T. Gogami ; ^{gogami@scphys.kyoto-u.ac.jp" class="auth_mail" title="E-mail the corresponding author} ; N. Amamo ; S. Kanatsuki ; T. Nagae ; K. Takenaka
• 关键词：Ξ&minus ; Ξ&minus ; hypernuclear spectroscopy ; Water Čerenkov detector ; On-line proton rejection
• 刊名：Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
• 出版年：2016
• 出版时间：1 May 2016
• 年：2016
• 卷：817
• 期：Complete
• 页码：70-84
• 全文大小：3378 K

文摘

The missing mass spectroscopy of Ξ⁻${\mathrm{\Xi }}^{-}$ hypernuclei with the (K⁻,K⁺${\mathrm{K}}^{-},{\mathrm{K}}^{+}$) reaction is planned to be performed at the J-PARC K1.8 beam line by using a new magnetic spectrometer, Strangeness -2 Spectrometer (S-2S). A Čerenkov detector with a radiation medium of pure water (refractive index of 1.33) is designed to be used for on-line proton rejection for a momentum range of 1.2–1.6 GeV/c   in S-2S. Prototype water Čerenkov detectors were developed and tested with positron beams and cosmic rays to estimate their proton-rejection capability. We achieved an average number of photoelectrons of greater than 200 with the latest prototype for cosmic rays, which was stable during an expected beam time of one month. The performance of the prototype in the cosmic-ray test was well reproduced with a Monte Carlo simulation in which some input parameters were adjusted. Based on the Monte Carlo simulation, we expect to achieve bbdb4794a70997949f0a5b232a184d" title="Click to view the MathML source">>90%$>90\%$ proton-rejection efficiency while maintaining $>95\%{\mathrm{K}}^{+}$ survival ratio in the whole S-2S acceptance. The performance satisfies the requirements to conduct the spectroscopic study of Ξ⁻${\mathrm{\Xi }}^{-}$ hypernuclei at J-PARC.