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تسجيل مستخدم جديدCharged-particle veto detector for the $K_L to pi^0 u bar u$ study in the J-PARC K$^O$TO experiment
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Yosuke Maeda
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A charged-particle veto detector was constructed to study the rare decay $K_{L} rightarrow pi^{0} u bar{ u}$ in the J-PARC K$^{mathrm{O}}$TO experiment. This detector consists of 3mm-thick plastic scintillator strips and wavelength shifting fibers coupled with MPPCs at the both ends, which makes it possible to obtain large light output over the wide region. After the construction and installation to the K$^{mathrm{O}}$TO experimental area, its performance was studied using charged particles from $K_{mathrm{L}}$ decays. As a preliminary result, we found that the detector had the light yield larger than 10p.e./100keV and the timing resolution better than 3ns for most regions, which satisfied the requirements to achieve the standard model sensitivety($sim10^{-11}$) for the $K_{L} rightarrow pi^{0} u bar{ u}$ detection.
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The rare decay $K_L !to! pi^0 u overline{ u}$ was studied with the dataset taken at the J-PARC KOTO experiment in 2016, 2017, and 2018. With a single event sensitivity of $( 7.20 pm 0.05_{rm stat} pm 0.66_{rm syst} ) times 10^{-10}$, three candidate
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