Current status and history for the lowering of background of liquid scintillation counters

In 1971, Aloka Co. Ltd. developed the world's first low background liquid scintillation counter for 100mL vials to measure the low level of 3H occurring in the nature, based on the characteristics of radiation measurement by the liquid scintillation method. Numerous performance enhancements, including low background technique for liquid scintillation counting have achieved by Hitachi Aloka Medical Co. Ltd. An overview of the enhancements and development of low background liquid scintillation counter are reviewed briefly. (author)