Experimental study on background reduction of γ-ray spectrometer using anticoincidence and thermal neutron shielding methods

Based on material shielding,a newly developed anti-cosmic low-background γ-ray spectrometer is used to conduct experimental study on background reduction of secondary cosmic muons and neutrons by combining anticoincidence shielding with thermal neutron shielding. The results show that the anticoincidence shielding (plastic scintillation detector) can reduce the μ background significantly on the HPGe detector, while effectively suppressing the background from the fast neutron inelastic scattering on the Ge crystal and shielding materials. The suppression factor of the anticoincidence integrated background is up to 8 in the energy region of 100-2000 keV. The addition of thermal neutron shielding (Cd absorber) can obviously reduce the background generated by the thermal neutron captured in the Ge and shielding materials, increasing the suppression factor of 511 keV γ-ray annihilation peak background from 5.8 to 20.7, and the suppression factor of anticoincidence integrated background in 100-2000 keV to 13.2. (authors)