Murayama, R; Komatsubara, TK; Lim, GY; Matsumura, T; Miyazaki, K; Nanjo, H; Nomura, T; Okuno, H; Pod, E; Sato, T; Shiomi, K; Togawa, M; Tajima, Y; Toyoda, T; Wah, YW; Watanabe, H; Yamanaka, T; Ahn, JK; Comfort, J; Inagaki, T; Isoe, M; Kamiji, I; Kim, EJ; Kim, JL; ,
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
ISSN: 0168-9002
The J-PARC KOTO experiment aims to explore new physics beyond the Standard Model through the K-L -> pi(0)nu(nu) over bar decay. We installed a new photon-veto detector, named the Inner Barrel (IB), to improve the detection efficiency and the timing resolution for photons in the region transverse to the neutral beam. The IB is a 2.8-m-long cylindrical detector with a 1.5 m inner diameter. The IB is a lead-scintillator sampling shower counter with a 5-radiation-length thickness and with a low mass support structure, and fits inside the 14-radiation-length-thick cylindrical detector. Scintillating light is read out from both ends via wavelength shifting fibers with a short decay time. The design, construction and performance of the IB are presented in this paper.