Advanced measurement control for gamma spectrometric measurements

In the gamma-ray spectrometric measurements, usual problem is related to how long to collect the spectrum from the detector to achieve statistically good data for analysis without unreasonable long time. Usually the selection of data acquisition time has been based on experienced user decision; samples are treated with standard procedures to ensure basic detection capability within reasonable data acquisition time. The intention of this study was to find out possibilities to make the laboratory measurement control automatic and to find out if we can increase the detection capability and free laboratory resources (i.e. detector time) for other purposes. Applications presented here were built into UniSampo gamma spectrum analysis software and they can be used as part of laboratory practice. The main problem has two components: statistics and decay of radionuclides. Specially, in the environmental samples where we are searching traces of forensic information, we have to deal with complex mechanics where naturally occurring radionuclides are masking the nuclides of our interest and on the other hand decay of the interesting fission and activation products is limiting the sample cooling time and data acquisition time. Furthermore, the concentrations of radionuclides of interest may be sometimes so high that no cooling is needed at all and we can get the analysis information of those cases out as soon as possible.