Scattered proton detection system for scattering experiment with the cylindrical scintillating fiber tracker and BGO calorimeters

円筒形シンチレーションファイバー検出器とBGOカロりメータからなるシグマ陽子散乱実験のための散乱陽子検出システム

中田 祥之; 長谷川 勝一   ; 早川 修平

Nakada, Yoshiyuki; Hasegawa, Shoichi; Hayakawa, Shuhei

J-PARC K1.8ビームラインにおいてシグマ陽子散乱実験を計画している。本実験では散乱された陽子の飛跡とエネルギーと生成したK中間子の運動量から運動学を計算することで、散乱事象を再構成する手法を用いる。このため、高い散乱事象検出効率を達成するために、散乱された陽子の飛跡とエネルギーを高い精度で測定する必要がある。現在、散乱陽子の飛跡とエネルギーを高精度で測定するための散乱陽子検出システムを開発中であり、この散乱陽子検出システムのテストを2014年秋に80MeV陽子とポリエチレン標的を用いて東北大学サイクロトロンラジオアイソトープセンターで行った。そこで得られた結果についての講演を行う。

The proton detection system is under construction for the scattering experiment at J-PARC (J-PARC E40) for the purpose of investigating Baryon-Baryon interaction. The E40 experiment is a double-scattering experiment, that is, followed by in the liquid hydrogen () target. Then, the scattering events are identified by tagging the production with spectrometer systems, and by measuring the scattered proton with the proton detection system. The momentum of produced can be calculated from the momenta of and measured by the spectrometer systems. We can reconstruct scattering events using their kinematics. The scattered proton detection system (CATCH: Cylindrical Active Tracker and Calorimeter system for Hyperon scattering) for this experiment is composed of cylindrical scintillating fiber tracker (CFT) and calorimeter of bismuth orthogermanate (BGO) crystals. Enough energy resolution of CFT to separate protons and s is essential for good S/N. The construction of the 2 layer of CFT (CFT-2 and CFT-UV2) was completed. We performed a test experiment at the Cyclotron and Radioisotope Center in Tohoku University to evaluate its performance. proton beams were irradiated to polyethylene () film target, and proton scattering data were acquired. Using the and scattering data, we evaluated proton detection efficiency of CFT-2 and -UV2 and their energy resolution.