Abstract
Multi-turn charge-exchange beam injection is the key technique to achieve high-intensity proton beam accelerators. In J-PARC RCS, 400-MeV H- beams from LINAC are injected into stripper foils such that most of the beams are converted into protons. The stripper foils are irradiated not only with the injected H- beams but also with the protons circulating during the beam injection period. 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 foils. Therefore, an activation analysis method that uses sample pieces is required to investigate the secondary particle. Furthermore, a new experimental system to measure secondary particles from the foil was installed at the L3BT 100BD line. Initial testing of the system has been completed, and beam testing will commence in October 2018.
Highlights
The 3-GeV Rapid Cycling Synchrotron (RCS) in Japan Proton Accelerator Research Complex (J-PARC) accelerates protons from a kinetic energy of 400 MeV to 3 GeV with a repetition rate of 25 Hz, and the aim is to achieve beam output power of 1 MW
The RCS performs two main functions: it serves as a proton driver for neutron/muon production at the Material and Life science experimental Facility and as a booster of the Main Ring synchrotron (MR) at the Hadron experimental facility (HD) and Neutrino experimental facility (NU) [1]
To achieve MW-class high-power proton beams in J-PARC, multi-turn charge-exchange H- beam injection scheme with stripper foils has been adopted in RCS
Summary
The 3-GeV Rapid Cycling Synchrotron (RCS) in Japan Proton Accelerator Research Complex (J-PARC) accelerates protons from a kinetic energy of 400 MeV to 3 GeV with a repetition rate of 25 Hz, and the aim is to achieve beam output power of 1 MW. To achieve MW-class high-power proton beams in J-PARC, multi-turn charge-exchange H- beam injection scheme with stripper foils has been adopted in RCS. To confirm the effect of beam loss localization, residual dose rates along the ring were measured periodically. The measurement results showed that unexpectedly high levels of radioactivity were found around the stripper foil [6]. After the two LINAC upgrades, finer beam tuning was performed to reduce beam losses in RCS. Radioactivity around the foil increased after the LINAC upgrade, and the residual dose rate around the foil could not be reduced drastically. It is very important to understand the cause of this radioactivity and reduce the residual dose rate around the foil to achieve stable user operation in
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