Experiments with K-meson decays Komatsubara, T.K.
Progress in particle and nuclear physics,
October 2012, Letnik:
67, Številka:
4
Journal Article
Recenzirano
Odprti dostop
Recent results and future prospects of particle physics experiments with neutral and charged K-meson (kaon) decays are reviewed. Topics include CP violation, rare decays, leptons in kaon decays, ...tests of CPT and quantum mechanics, radiative decays, hadrons in kaon decays, basic observables, Vus and CKM unitarity, and exotic searches. Experimental techniques developed for the kaon decay experiments are discussed.
First search for KL → π0γ Shimizu, N
Physical review. D,
09/2020, Letnik:
102, Številka:
5
Journal Article
Recenzirano
We report the first search for the KL → π0γ decay, which is forbidden by Lorentz invariance, using the data from 2016 to 2018 at the J-PARC KOTO experiment. With a single event sensitivity of (7.1 ± ...0. 3stat ± 1. 6syst) × 10−8, no candidate event was observed in the signal region. The upper limit on the branching fraction was set to be 1.7 × 10−7 at the 90% confidence level.
A search for the rare decay KL → π0νν¯ was performed. With the data collected in 2015, corresponding to 2.2 × 1019 protons on target, a single event sensitivity of (1.30 ± 0.01stat ± 0.14syst) × 10–9 ...was achieved and no candidate events were observed. We set an upper limit of 3.0 × 10–9 for the branching fraction of KL → π0νν¯ at the 90% confidence level (C.L.), which improved the previous limit by almost an order of magnitude. An upper limit for KL → π0X0 was also set as 2.4 × 10–9 at the 90% C.L., where X0 is an invisible boson with a mass of 135 MeV /c2.
We developed a high voltage system for the electromagnetic calorimeter of the KOTO detector. The system is designed around a low noise, low power Cockcroft–Walton (CW) photomultiplier tube base with ...a high gain preamplifier. The low power makes it suitable for operations in vacuum. The low noise and high gain allow detecting signals in the 1MeV range. We achieved a final noise level below 180μVrms for a preamplifier gain of more than 40. A vacuum tolerant control system for the CW bases power distribution was also designed. This system is able to control and monitor the high voltage of each individual base.
CsI calorimeter for the J-PARC KOTO experiment Sato, K.; Lee, J.W.; Banno, S. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2020, Letnik:
982, Številka:
C
Journal Article
Recenzirano
Odprti dostop
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∕EGeV% in the inner region of the calorimeter.
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