Influences of fusion neutrons on Compton suppressed γ-spectrum analyses at the HL-2A tokamak

Abstract

The newly-built Compton suppression system at the HL-2A tokamak works in a harsh fusion neutron field especially when the second neutral beam injection system is put into application. The present paper performed Geant4 simulations to study the influences of fusion neutrons on Compton suppressed γ-spectrum analyses. The simulation data show that the influence of fusion neutrons on suppressed γ-spectrum shape is limited, while the influence on detection efficiencies is considerable. Consequently, the changes of detection efficiencies caused by the coexisting neutrons must be taken into account in the subsequent γ-spectrum analyses. Hence, the empirical formulas of γ-ray detection efficiencies of the Compton suppression system, which had considered the influences of fusion neutrons, were put forward and then applied to unfold the experimental γ-spectra. This work lays a superior foundation for the further analyses of the Compton suppressed γ-spectra at the HL-2A tokamak.