REDUCING BACKGROUND FROM COSMIC RAYS IN THE ANTICOINCIDENCE SHIELDED GAMMA-RAY SPECTROMETER

In the measurements of low level radioation the background of a detector ordetection system should be as low as possible. In laboratory the backgroundusually comes from three sources: radioactive impurities in the detector andshielding material, environment radioation from the laboratory and the cosmicrays. In this work, the measures is taken to reduce the background causedby the first two effects. Special effort is made to overcome the backgroundfrom the cosmic rays. As a result for our spectrometer a background rate as lowas 8.7±0.1 count/min over the energy range from 100 to 2000 keV is obtained,which is presently one of the lowest among the spectrometers of its kind.