Present status and future prospect of the open utilization in HIMAC

The first medically-dedicated heavy ion accelerator facility in the world was constructed at NIRS and the treatment of cancer patients began in June, 1994. A number of the treated patients exceeds 500 in 4.5 years. In a fiscal year of 1997, a number of accepted proposals is 129 and a number of the outside users is 330. HIMAC is operated 24 hours from Tuesday to Friday while the treatment is carried out in the daytime. The rest of the beam time (nights and weekends) is used for these researches under this utilization system. Beam time provided to the users in FY 1997 is 2800 hours for the clinical trial and 3100 hours for the open utilization. Ion species are C (3760 hs), Ar (460 hs), Si (380 hs), Ne (270 hs), He (170 hs) and H2+ (160 hs). The beams of Fe and Kr will be added in a list of available ions. These increase of beam time is largely due to development of the time sharing mode in the linac system. Proposal from abroad increases gradually. For example, the NASA group is interested in using the beam in HIMAC for their research. The problem is the shortage of manpower who guides and helps the outside groups and infrastructure such as electronics or machine shops and accommodations, although they are indispensable for smooth running of the research. (J.P.N.)