Upgrade of the CsI calorimeter for the KOTO experiment
Abstract
The aim of the KOTO experiment is to study new physics beyond the standard model via a search for the rare decay {K}L\to {π }0ν \bar{ν }. The KOTO detector consists of the electromagnetic calorimeter and hermetic veto counters. To reach the Standard Model sensitivity, we need to reject the neutron-induced backgrounds by a factor of ten. In the summer of 2018, we will start to instrument the front surface of the CsI calorimeter with 4096 multi pixel photon counters (MPPCs) to measure the arrival-time difference between the signals at MPPCs and at photomultiplier tubes connected to the rear surface of the calorimeter. The depth of energy deposition in the shower is measured through the timing difference, which in turn helps to discriminate neutrons and photons. To manage the large number of MPPCs, we have developed an electronics to reduce the number of channels down to 256. The method of gluing between the MPPC and the CsI crystals has been also developed. Using a quartz plate as a medium, the condition of atness is assured in advance and a stable gluing can be performed. By developing a dedicated method to glue the MPPC with the quartz plate, the glue joint gets to be able to endure the decrease of temperature down to -20 °. The functionality of the developed hardwares were con rmed by two beam tests.
- Publication:
-
Journal of Physics Conference Series
- Pub Date:
- January 2019
- DOI:
- 10.1088/1742-6596/1162/1/012030
- Bibcode:
- 2019JPhCS1162a2030S