Comparison of two independent methods for determining the neutron/gamma sensitivity of a dosemeter

Results obtained with two independent methods for measuring the n/gamma sensitivity of non-hydrogenous dosemeters are compared for the neutron beam produced by 8.3 MeV deuterons on beryllium. In one method, a pure neutron field is simulated by taking the difference between measurements made at diffrent angles in a mixed field with an isotropic gamma-ray component. In the second method, the mixed (n+gamma) beam is purified by lead filtration. An assumption in the lead filtration method is that the background radiation is invariant under three different beam conditions. This assumption was found not be be valid in our experimental arrangement; and caused the values obtained for the n/gamma sensitivity to be systematically high. A modification was made in the lead filtration method so that the dosemeter response to background could be determined for each beam condition. Good agreement was obtained between the results of the spectral difference and modified lead filtration methods.