GEANT4 Simulation of the Focal Plane Detection Array of Gas-filled Recoil Separator

The gas-filled recoil nuclear separator SHANS(Spectrometer for Heavy Atoms and Nuclear Structure) is an important experimental device for synthesing new neutron-deficient actinide nuclides and studying α decay properties of heavy nuclides in China. In order to further improve the detective efficiency of the focal plane detector array for heavy nuclide α decay particles and \gamma rays, we plan to upgrade the existing detection instrument. The main work of this paper is to simulate the existing detector array by using the GEANT4 software based on Monte Carlo method. In order to verify the accuracy of the program, the simulation was compared with the experimental data. The results show that the detective efficiency of the new detector system for α decay particles is about 88%, and the detective efficiency for \gamma rays with an energy of 1 MeV is about 7%.