[Effect of chemical quenching on background counting rate in tritium channel of a large volume liquid scintillation counter].

Background counting rate in tritium channel of a large volume liquid scintillation counter increased with water content ranged 0 to 50% of liquid scintillator. This phenomenon can be explained as follows: The height of scintillation pulses of Compton electrons induced by background gamma radiation is lowered by chemical quenching and shifts to tritium channel. The background counting rate in tritium channel showed a linear relationship with external standard channel ratio of background samples. This relationship is applicable to determine the correct background counting rate for quenching samples and to achieve higher precision of tritium measurement.