Scintillation and ionization yields of helium-xenon gas mixture for application in neutron detectors

The scintillation and ionization yields of helium-xenon gas mixture were measured using a gridded ionization chamber with Am-241 alpha particles to study the potential of the mixture to be applied in neutron detectors. The ionization yields for various ratios of the mixture gases were obtained with gas pressures of 1.0, 0.657, and 0.100 MPa. The yield data were explained well using the ratio of the number of excited atoms to that of ionized atoms in helium, i.e. 0.541 +/- 0.005. The scintillation yield increased with xenon partial pressure and saturated at 10% of the total pressure, while the ionization yield increased up to 1.59 times of the initial value for pure helium at 1% of the total pressure then gradually increased to 1.8 times. The helium gas with added xenon at 10% of its pressure was suggested as a medium of a neutron detector with signal readouts from both scintillation and ionization, since it increases the scintillation yield to more than 1.1 times of pure xenon and increases the ionization yield to more than increases 1.8 times of pure helium. (C) 2020 The Japan Society of Applied Physics