Abstract
To estimate the lifetime and the radiation dose of the proton beam window used in the spallation neutron source at J-PARC, it is necessary to understand the accuracy of the production cross section of 3-GeV protons. To obtain data on aluminum, the reaction cross section of aluminum was measured at the entrance of the beam dump placed in the 3-GeV proton synchrotron. Owing to the use of well-calibrated current transformers and a well-collimated beam, the present data has good accuracy. After irradiation, the cross sections of Al(p,x)7 Be, Al(p,x)22 Na-22 and Al(p,x)24 Na were obtained by gamma-ray spectroscopy using a Ge detector. It was found that the evaluated data of JENDL/HE-2007 agree well with the current experimental data, whereas intra-nuclear cascade models (Bertini, INCL-4.6, and JAM) with the GEM statistical decay model underestimate by about 30% in general. Moreover, gas production, such as T and He, and the cross sections were measured for carbon, which was utilized as the muon production target in J-PARC. The experiment was performed with 3-GeV proton having beam power of 0.5 MW, and the gasses emitted in the process were observed using a quadrupole mass spectrometer in the vacuum line for beam transport to the mercury target. It was found that the JENDL/HE-2007 data agree well with the present experimental data.
Highlights
The Japan Proton Accelerator Research Complex (J-PARC) [1] houses a MW-class pulsed neutron source in the Materials and Life Science Experimental Facility (MLF) within the Japan Spallation Neutron Source (JSNS) [2] and the Muon Science Facility [3]
The escape of residual nuclides from the sample was calculated with PHITS code[9] using the cascade model of INCL-4.6[10], and it was found to be lower than a few percent
The JAM and the INCL-4.6 cascade models in the PHITS code overestimated compared to the present result
Summary
The Japan Proton Accelerator Research Complex (J-PARC) [1] houses a MW-class pulsed neutron source in the Materials and Life Science Experimental Facility (MLF) within the Japan Spallation Neutron Source (JSNS) [2] and the Muon Science Facility [3]. To efficiently use protons for particle production, both targets are aligned in a cascade scheme, with the graphite target placed 33 m upstream of the neutron target. For both sources, the 3 GeV proton beam is delivered from a rapid cycling synchrotron (RCS) to the targets by the 3 GeV RCS to neutron facility beam transport (3NBT) [4, 5]. Before injection into the RCS, the proton beam is accelerated up to 0.4 GeV by a LINAC. The extracted 3 GeV proton beam, with a 150-ns bunch width and spacing of 600 ns, is transferred to the muon production target and the spallation neutron source
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