News from Japan Proton Accelerator Research Complex

Takenori Suzuki (KEK)
Tokushi Shibata (KEK)
Hiroshi Nakashima (JAERI)

Japan Proton Accelerator Research Complex (J-PARC) is a high-intensity proton accelerator facility, which aims to study frontier science in nuclear and particle physics, materials and life sciences, and nuclear technology. The plan has been discussed and proposed jointly by the High-Energy Accelerator Research Organization (KEK) and the Japan Atomic Energy Research Institute (JAERI). Previously these institutions proposed the Japan Hadron Facility (JHF) at KEK and the Neutron Science Project (NSP) at JAERI, respectively. J-PARC is based on these past proposals, and scientists and engineers from KEK and JAERI are jointly working for the project.

The completed facilities of J-PARC will comprise three accelerators (a 400-MeV proton linear accelerator, a 3-GeV synchrotron [RCS], and a 50-GeV synchrotron [MR]) and four experimental facilities (Materials and Life Sciences Facility [MLF], Nuclear and Particle Physics Facility [NP], Neutrino Experimental Facility [NEF], and Accelerator-Driven Transmutation Experimental Facility [ADS]).

When J-PARC was funded three years ago by the government, the NEF and ADS were assigned to the second phase of the project, which would be constructed after the completion of the Phase I project. Since Professor Koshiba was awarded the Nobel Prize for neutrino science in 2002, many scientists recommended that the NEF should be realized as early as possible. After intensive discussions through the Council for Science and Technology Policy, Cabinet Office (CSTP) of Japan, and the special working group formed for the evaluation of the neutrino project, finally the NEF project was authorized in December 2003 as part of Phase I for the Japanese fiscal year (JFY) of 2004 (April to March in Japan). At this stage, the test beam of Phase I is scheduled as follows: linear accelerator--the middle of JFY 2006; RCS--the beginning of JFY 2007; MR--the middle of JFY 2007; MLF--the middle of JFY 2007; NP--the beginning of JFY 2008; and NEF--the beginning of JFY 2009.

From a radiation safety point of view, many accelerator components, magnets, scrapers, and septa will be expected to be highly activated. As J-PARC will be the first facility in Japan to handle such highly activated accelerator components due to the 1-MW beam, we are studying how international accelerator facilities have been facing these problems and how they have managed to reduce workers' radiation doses. We asked radiation officers of these facilities to supply their past data about the trends in dose to radiation workers. We would like to express our gratitude to those facilities that sent us their data.