Design of the radiation shield and collimator for neutron and gamma-ray diagnostics at EAST

New compact radiation shields have been designed to reduce the scattered neutrons and background gamma-rays for neutron and gamma-ray diagnostics in the EAST hall. The design focused on optimizing radiation shielding performance versus volume and weight to fit the small amount of available space outside the tokamak device. Based on the Monte Carlo method and using the Geant4 tool kit, three-dimensional models of the shield were created for material selection and structural design optimization. The 10-cm and 15-cm polyethylene doped with 12 wt.% B4C, and 10-cm cast lead were finally selected for the main body of the shield. In addition, the shape and structure of the collimator in the front half of the shield are optimized, and a replaceable aperture adjuster module design has been adopted for the collimator. For incident particles with different energies, the collimation efficiency of the collimator has also been calculated.