Geometry Optimization of Muon Production Graphite Target by 600 MeV Proton Beam

The Rare Isotope Science Project was launched in December 2011, and a heavy-ion accelerator complex in Korea, named RAON, has been designed, including a muon facility for muon spin rotation, relaxation, and resonance (μSR). In this study, the graphite target in RAON was designed to have a rotating ring shape and was cooled by radiative heat transfer, which presents advantages in the cool-down process such as a low-temperature gradient in the target and no necessity of a liquid coolant-cooling system. Monte-Carlo simulations and ANSYS calculations were performed to optimize the proton beam size and the dimensions of the target to produce a sufficient number of surface muons in a thermally stable condition. A comparison between the simulation and the experimental data was also included in this paper in order to obtain a reliable result. The expected number of surface muons was 6.942×108 with a 100 kW proton beam and Δp/p~5%. The maximum temperature was 2012 °K and the maximum stress in the target was 8.1598 kPa with the 400 kW proton beam, which guarantees safety during the replacement cycle of the target.