Proposal to Participate in J-Parc KL Experiment

During the previous grant period we have been working on the J-PARC KL E14 (KOTO) experiment with the goal to discover and measure the rate of the rare decay neutral kaons to a pion and two neutrinos. This CP-violating flavor changing neutral current decay proceeds through second-order weak interactions. Other, as yet undiscovered particles, which can mediate the decay could provide an enhancement to the branching ratio, which in the Standard Model predicted to be about 2.80E-11. The experiment is expected to observe 100 events at the Standard Model branching ratio for a 10% measurement. The experiment is a follow-up to E391a at KEK and has been approved as experiment E14 at J-PARC. The main barrel vacuum vessel, the charged veto detectors, and the main barrel photon veto system will be reused from E391a. The main calorimeter has been replaced with Cesium Iodide crystals that are both smaller to provide improved shower reconstruction and longer to prevent energy leakage out of the back of the calorimeter. New trigger and data acquisitions electronics will be used