CsI calorimeter for the J-PARC KOTO experiment

K. Sato, J. W. Lee, S. Banno, M. Campbell, J. Comfort, T. Furukawa, E. Iwai, N. Kawasaki, T. K. Komatsubara, G. Y. Lim, Y. Maeda, T. Masuda, T. Matsumura, D. Mcfarland, R. Murayama, D. Naito, Y. Nakaya, H. Nanjo, T. Nomura, Y. OdaniT. Ota, Y. D. Ri, M. Sasaki, N. Sasao, S. Seki, T. Shimogawa, T. Shinkawa, K. Shiomi, Y. Sugiyama, S. Suzuki, Y. Tajima, M. Tecchio, M. Togawa, T. Yamanaka, Y. Yanagida, H. Yokota, H. Yoshimoto, Y. W. Wah, H. Watanabe, J. Xu

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)


An electromagnetic calorimeter made of undoped CsI crystals is used in the J-PARC KOTO experiment to search for new physics beyond the standard model with the KL→π0νν̄ decay. The calorimeter is designed to operate in vacuum of 0.1 Pa and in a high-rate environment where the counting rate due to KL decays is O(100) kHz. A special method to calibrate the calorimeter during the data taking without using a tracking system for charged particles is reported. The energy, position, and timing resolutions of the calorimeter were evaluated in several beam tests, and the resolutions satisfy the required performance. The energy resolution with the total energy E is 0.66⊕1.81∕E[GeV]% in the inner region of the calorimeter.


  • Calorimeter
  • Pure CsI
  • Undoped CsI

ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Instrumentation


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