B-MESON PHYSICS BY ELECTRON-POSITRON COLLISIONS

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The final physics objective of this study is to measure the CP violation via B meson decays. In order to achieve that, we must realize a B-factory which produce a large number of B meson decays by asymmetric-energy electron-position collider. We started this study as basic and realistic preparation of the B-factory in Japan. Fortunately, the B-factory project at KEK was approved in 1994, we could make systematic and thorough activities for the construction of B-factory in these three years. The main results are summarized as follows.(1) The first yearWe have organized the world-wide experimental team, named as 'BELLE collaboration', based on the collaboration of this Grant-in-Aid for Co-operative Research (A). We then could complete a Proposal for B-factory Experiment, as a 'Letter of Intent.'. The first design baseline is that the BELLE detector would be constructed at Fuji experimental hall, using VENUS super-conducting magnet and support structure.(2) The second yearThe design of the accelerator was changed, especially, the interaction region was moved to Tukuba experimental hall. Therefore, the design for BELLE detector was drastically changed, e.g., new magnet, new support structure, new shape of vertex detector etc. We have completed a detailed 'Technical Design Report' in this year.(3) The third yearMost of the specifications had been fixed by this year except for Particle Identifier (PID). After long term of dedicated efforts, we have selected a Aerogel Cherenkov counter and TOF as the baseline for PID.Since all the specifications were fixed, we can start the detector integration from next year. As a whole, we could achieve the major part of the preparation for the construction of the B factory as expected.