Cosmic-ray test of a time-of-flight detector for double-strangeness experiments at J-PARC

J-PARCにおけるダブルストレンジネス実験のための飛行時間測定用検出器の宇宙線によるテスト

Kim, S. H.*; Hwang, S.; Ahn, J. K.*; 江川 弘行; 早川 修平; Hong, B.*; 細見 健二  ; 今井 憲一; Kim, M. H.*; Lee, J. Y.*; Moon, T. J.*; Ryu, S. Y.*; 佐甲 博之   ; 高橋 俊行*; 谷田 聖   

Kim, S. H.*; Hwang, S.; Ahn, J. K.*; Ekawa, Hiroyuki; Hayakawa, Shuhei; Hong, B.*; Hosomi, Kenji; Imai, Kenichi; Kim, M. H.*; Lee, J. Y.*; Moon, T. J.*; Ryu, S. Y.*; Sako, Hiroyuki; Takahashi, Toshiyuki*; Tanida, Kiyoshi

We have developed a time-of-flight (ToF) array consisting of 24 plastic scintillators for triggering and timing measurements in a series of planned experiments to study double-strangeness hadronic and nuclear systems at the K1.8 beamline of J-PARC. Each ToF scintillator is 180 cm long with a cross-section of 83 cm and is read out by H1949-50 photomultiplier tubes at both ends. The timing and attenuation properties of the scintillators are measured using cosmic-ray muons and rays from . The cosmic-ray muon events are triggered by three pairs of 120-cm-long plastic scintillators, sandwiching the ToF array. The intrinsic time resolutions of the scintillators are estimated to be in the range 60-100 ps, which is adequate for reliable separation between and at 1.2 GeV/. The attenuation length is measured to be approximately 210 cm, which is half that for a bulk scintillator.