Characteristics of a liquid scintillation spectrometer and experiment using it

The liquid scintillation counter used for characteristic measurement was a Packard's low-background liquid scintillation spectrometer system. For its purpose, the apparatus possesses a preset channel for three nuclides of 3H, 14C and 125I. That is, the gain and the discrimination level are set automatically, so that 300 samples can be measured continuously and repetitively. (Setting of the gain and discrimination level manually without using the preset channel is of course possible.) For the radioactivity measurement of the three nuclides, the preset channel is reliable, but its characteristic measurement may be worthwhile, and becomes necessary for other radioactivity measurements. Characteristic measurements were made using no-quenching standard sources and 10-class quenched standard sources of 3H and 14C. For experiment, fast and thermal neutron fluxes were measured in an irradiation field, using phosphorus powder. (Mori, K.)