PoS - Proceedings of Science
Volume 332 - XIV International Conference on Heavy Quarks and Leptons (HQL2018) - Kaon Physics
The both-end readout system of the KOTO CsI calorimeter
N. Hara*  on behalf of the KOTO Collaboration
Full text: pdf
Pre-published on: December 05, 2018
Published on: December 11, 2018
The purpose of the J-PARC KOTO experiment is to observe the rare decay $K_L\to\pi^0\nu\bar{\nu}$. This decay is highly suppressed in the Standard Model ($\rm{BR} = 3.0 \times 10^{-11}$) because it violates the CP symmetry directly. This decay mode is thus sensitive to new physics that breaks the CP symmetry. The signal of $K_L\to\pi^0\nu\bar{\nu}$ is only two gammas with a finite transverse momentum. To detect this signal, we have an electromagnetic calorimeter made of CsI crystals. One of the main background sources is beam-halo neutrons producing two fake clusters in the calorimeter. To suppress the neutron background, we are preparing to attach 4096 Multi Pixel Photon Counters (MPPCs) on the upstream side of the crystals. We can distinguish neutrons and photons by measuring the timing difference between the MPPCs, and PMTs attached on the downstream side of the crystals.
For the both-end readout system, we developed front-end circuits to reduce the number of readout channel and to control the MPPCs.
DOI: https://doi.org/10.22323/1.332.0034
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