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Yoshimoto, Masahiro; Okabe, Kota; Harada, Hiroyuki; Kinsho, Michikazu; Kato, Shinichi*
no journal, ,
The charge exchange multi-turn beam injection scheme is adopted in the J-PARC 3GeV Rapid Cycling Synchrotron Accelerator (RCS) due to achieve 1MW beam power operation. In the conventional multi-turn beam injection scheme, which is provided by only the septum and bump magnets, injecting turn numbers are limited by the beam losses at the septum. On the other hand, charge exchange multi-turn beam injection does not cause the beam losses at the septum; there is no restriction in principle on the injecting turn number. However, high residual doses are observed around the stripper foil. During the charge exchange multi-turn beam injection, not only the injecting beam but also circulating beam hit the foil, and then a large number of secondary particles, namely protons and neutrons, are generated. PHITS simulation results indicate that the secondary particles cause the high residual doses around the foil. To verify this examination, secondary particles measurement is key issue. But injection system is too complex to detect the pure signals of the secondary particles from the stripper foil. Thus, a new independent type foil introducing device is installed in the 100
dump beam transport line in order to construct a simple experimental system for secondary particle measurements. We plan the two experiments by using this system; one is a directly secondary particle detecting method, and the other is a radioactivation analysis method with metal sample pieces. Now, we started the study of how the identification of species and energies of the secondary particles with PHITS code. In this presentation, we report the simulation results of the utility of the radioactivation analysis method.
Yoshimoto, Masahiro; Okabe, Kota; Kinsho, Michikazu
no journal, ,
The 3 GeV Rapid Cycling Synchrotron (RCS) of the Japan Proton Accelerator Research Complex (J-PARC) adopts the charge-exchange multi-turn beam injection with stripper foils to achieve 1 MW class high power beam operation. Residual dose measurement and particle simulation by the PHTS suggest that the high radio-activation at the injection area is caused by the secondary particles generated by interaction between the stripper foil and the injecting and circulating beam. In order to measure the secondary particles from the stripper foil directly, a new radiation detector combined Stilbene of an organic scintillator and a normal plastic scintillator is developed. This new radiation detector aims for discrimination among proton, neutron, and gamma ray. In the first step of the development, Stilbene scintillator is assembled and tested in the RCS utility tunnel, where proton does not exist because there is the thick concrete shield between the accelerator tunnel and the utility tunnel. The Stilbene scintillator can detect and discriminate the neutron and gamma ray experimentally. In this presentation, we report the discrimination test with the Stilbene scintillator in the utility tunnel in detail.
Yoshimoto, Masahiro; Okabe, Kota; Kinsho, Michikazu
no journal, ,
In the J-PARC RCS, 400 MeV H
beams from the LINAC are injected to the stripper foils so that the most of beams are converted to protons. The stripper foil is irradiated not only by the injected H beams but also by the circulating protons. The high energy and intense beam irradiation into the foil generates secondary neutrons and protons via nuclear reactions. These secondary particles cause high residual activation around the stripper foil. To measure the secondary particles from the stripper foil, the particle detector system is required to discriminate among proton, neutrons and 
rays. Then, we develop the detector system combining a stilbene organic scintillator and a plastic scintillator. The stilbene scintillator can discriminate rays and other particles (protons and neutrons) with the Pulse Shape Discrimination (PSD) function. Furthermore, it can separate protons from neutrons by using the plastic scintillator which is set on the front of the stilbene scintillator. In this presentation, we report the PSD performance test of the stilbene scintillator in the utility tunnel in the RCS.
Yoshimoto, Masahiro; Okabe, Kota; Harada, Hiroyuki; Kinsho, Michikazu
no journal, ,
no abstracts in English