A new cylindrical photon-veto detector for the KL→π0νν¯ experiment

R. Murayama, M. Togawa, J. K. Ahn, J. Comfort, T. Inagaki, M. Isoe, I. Kamiji, E. J. Kim, J. L. Kim, T. K. Komatsubara, G. Y. Lim, T. Matsumura, K. Miyazaki, H. Nanjo, T. Nomura, H. Okuno, E. Pod, T. Sato, K. Shiomi, Y. TajimaT. Toyoda, Y. W. Wah, H. Watanabe, T. Yamanaka

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)


The J-PARC KOTO experiment aims to explore new physics beyond the Standard Model through the KL→π0νν¯ 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.


  • Kaon rare decay
  • Photon veto
  • Wavelength shifting (WLS) fiber

ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Instrumentation


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