Commissioning run of the long-baseline neutrino oscillation experiment at the 12-GeV KEK-PS

A prompt report for the commissioning run of the long-baseline neutrino oscillation experiments is presented. Improvement of the KEK-PS main ring has been performed for recent years in order to prepare the long-baseline neutrino oscillation experiment. Intensity upgrade studies and the hardware improvements result in a factor of 50% increase in the beam intensity to 5-6/spl times/10/sup 12/ ppp up to now. It depends on the reduction of the micro-instability at the crossing of the transition energy and the fine tuning of the closed orbit distortion and so on. The neutrino oscillation experiment requests the fast extraction. It needs to construct the fast kicker magnet system, consists of the 12.5 ohm kicker magnets and Blumlein power supplies, and to re-construct the septum magnets and some other equipment. These works have been under going during a long shut down, which was scheduled for the preparation and construction of the neutrino oscillation experiments facility until January, 1999. The switching of the fast extraction and the slow extraction will be possible without the evacuation of the equipment in order to serve the beam for the multi-users as effective as possible. The prompt results of the commissioning run, which will start at the end of January 1999, and the performance of the KEK-PS main ring are presented.