Intensity upgrade studies at the KEK-PS

Intensity upgrade studies have been performed at the KEK-PS for recent years in order to meet the need of new physics researches, especially the long base line neutrino oscillation experiment. Studies are concentrated on the reduction of the beam losses during injection, at the acceleration start and at the passing the transition energy. Obtained results to date are 6.8/spl times/10/sup 12/ particles at the acceleration start and 6.1/spl times/10/sup 12/ particles after acceleration, however an average beam intensity of 3-5/spl times/10/sup 12/ ppp are currently supplied for the experiments due to the beam loss during the slow extraction. We report the present results of these studies.