Evaluation of the influence of samples properties and geometry in gamma ray spectrometry

Variations in sample properties and sample geometry can occur in the measurements of standards and samples for neutron activation analysis. This work presents an evaluation of errors in gamma ray spectrometric analyses due to variations in sample properties and geometry, dead time of the system and pile up of pulses. To study these effects, simulated samples were prepared using 152 Eu tracer solutions. Gamma ray measurements were carried out by using an hyperpure Ge detector connected a gamma ray spectrometer. As expected, the results have indicated that sample self - absorption depends on sample density and the gamma ray energy. Counting geometry errors were the most important source of errors when samples are measured close to the detector. The sample holder thickness can also alter the measurements depending on the gamma ray energy. To avoid the overall correction for dead time and pile-up effects, the percentage of dead time has to be lower than 15%. (author)