A simple and fast procedure for absolute activity determination

A convenient procedure for determining sample activities using a HPGe detector based gamma-ray spectrometer with a 28 K microcomputer is described. Two BASIC programs for gamma spectrum analysis employing convolution with zero-area rectangular transforms have been written. Overlapping of peaks is accounted for to a limited extent. A few precalibrations are necessary to set parameters incorporated in the spectrum analysis programs. Separate programs are used for fast and easy energy, efficiency and peak intensity calibration. All programs are stored an cassette tape. A modification of a recently introduced 6-parameter detector efficiency model is proposed and tested. By means of this model the efficiency can be accurately determined from 60 keV upwards. m e best achievable accuracy in activity determination is about 2.5 %. A 4096-channel spectrum is typically processed in about 10 minutes. The possibility of coding the spectrum transformation in machine language using integer arithmetic will be investigated. This would substantially reduce the processing time.