title: Improving the assessment of activity in samples with non-uniform distribution using the sum peak count rate.
abstract: In this work a method for the evaluation of the activity when a point source containing (60)Co is located in an unknown position within a sample is developed. The method can be applied if the count rate in the 2,505 keV sum peak has an acceptable uncertainty. It is based on the correlation between the apparent efficiency for the 1,173 keV peak and the ratio of the count rate in the sum peak of 2,505 keV and in the 1,332 keV peak. The correlation was observed in the measurements of a (60)Co point source located in various positions in a soil sample. The measurements were done with a 47% efficiency n-type HPGe detector. The correlation is also observed in the measurements and simulations done with a Compton-suppressed spectrometer having a 100% n-type HPGe detector. The results obtained with the proposed method are less affected by the uncertainty of the position of the point source than the results obtained using the standard methods of activity evaluation.
authors.affiliation: Horia Hulubei National Institute for Physics and Nuclear Engineering, 077125 Magurele, Romania.
authors.forename: Rares
authors.initials: R
authors.lastname: Suvaila
authors.forename: Iolanda
authors.initials: I
authors.lastname: Osvath
authors.forename: Octavian
authors.initials: O
authors.lastname: Sima
mesh_terms: D000465:Algorithms; D003037:Cobalt Radioisotopes / Q000032:analysis*; D003627:Data Interpretation, Statistical; D011829:Radiation Dosage; D015203:Reproducibility of Results; D018401:Sample Size; D012680:Sensitivity and Specificity; D012990:Soil Pollutants, Radioactive / Q000032:analysis*; D013051:Spectrometry, Gamma / Q000379:methods*; D016008:Statistical Distributions
chemical_list: D003037:Cobalt Radioisotopes; D012990:Soil Pollutants, Radioactive
keywords: (60)Co; Coincidence summing effects; Gamma-ray spectrometry; Hot particle; Monte Carlo simulation