Detector R&D for stopped KィイD1+ィエD1 decay experiment

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Rare K-meson decay process is one of ideal probes to test the Standard Model and search for new physics. The aim of this R&D project is to develop hermetic detector for stopped KィイD1+ィエD1 decay experiment in high-intensity environment.We pursued the detector R&D as follows :1. We analyzed the data taken in '95-'97 by the international collaboration E787 at Brookhaven National Laboratory to obtain physics outputs and know if future upgrades concerning hardware and software were possible. (1) Based on one observed even of KィイD1+ィエD1→πィイD1+ィエD1νν, we concluded that the branching ratio is B(KィイD1+ィエD1→πィイD1+ィエD1νν) = (1.6 +3.8-1.4) x 10ィイD1-10ィエD1. (2) We analyzed by-product processes accompanying νray in the final state. New physics results for KィイD1+ィエD1→πィイD1+ィエD1πィイD10ィエD1γ, μィイD1+ィエD1νγ,πィイD1+ィエD1γ processes were presented at international conferences. (3) Study of the detector upgrade was carried on and summarized as a proposal BML-E949.2. We investigated performance of GSO and PbWO4. (1) R&D of detecting track position and track time using GSO-bar and plastic-scintillator bar. (2) Test of Cherenkov-light output by changing the La concentration.3. We developed a fast decision trigger circuits with ALTERA chip to made efficient and flexible data taking possible.4. "International Workshop on CP Violation in K" and "Workshop on Chiral Dynamics and related Particle and Nuclear Physics Experiments" were held at KEK-Tanashi, where future prospects of the K-decay physics were actively discussed.