Preliminary Studies On Shielding Of EMuS Thick Target And Collimation Of High Energy Proton Beam

In August 2018,the Chinese Spallation Neutron Source(CSNS)was completed and officially start the operation,which provided an important basic condition for the construction of China's moun source.As one of the important research platforms for CSNS future plan.An Experimental Muon Source(EMuS)will be built in the highenergy proton experimental area of CSNS.The CSNS accelerator delivers a proton beam to EMuS with a beam power of 5 kW and an energy of 1.6 GeV.After the highenergy proton beam bombards the muon target,the severe radiation is generated around target area and on the fore-and-aft proton beam line.Even on the case of the beam shutdown,there exists a strong induced radioactivity due to the activation of materials.And the residual dose around the target area is still high.Therefore,the radiation shielding is an important part of EMuS designs and researches.According to the multi-step development plan,EMuS has planned two schemes: a baby scheme and a baseline scheme.In this paper,the particle transport code of FLUKA based on the Monte Carlo method is used to calculate nuclear reaction processes of the 1.6 GeV high-energy proton beam on target and track the multi-particle transmission.The research works include: 1)analysis of beam spot and energy distribution after proton beam bombarding on the target,calculation of energy deposition distribution on target,calculation of muon yield,background analysis,analysis of radiation dose in the entire target area,and a reasonable resultant shielding scheme;2)Proton beam collimation analysis and collimator designs before and after the target on the baseline scheme.For baby scheme,the analyses and researches including the thermal deposition distribution on the target,the abandoned proton beam treatment,and the muon beam extraction method,were carried out.At the same time,by comparing the activation difference for different target container materials and shielding difference for different target-area shielding materials,a combined shielding scheme using a A5083 target container,an inner layer iron shielding and outer layer sodium-free concrete was determined.For baseline scheme,the initial proton beam collimators and shield designs were studied.For the abandoned proton beam after the target,the collimated scheme between target and dump is given,by which the beam loss position of the abandoned proton beam is effectively controlled.The researches in the thesis provide the target physical design parameters and shielding scheme for the first domestic muon source which is planned and constructed in the future.They can be significant as an engineering reference.