Automated construction of detector models for efficiency interpolation in gamma-ray spectrometry.
A method was developed for automated construction of detector models in gamma-ray spectrometry, which can be used in Monte Carlo calculations of efficiency calibration curves. Full-energy peak efficiencies were first measured for different gamma-ray energies and for a given sample-detector arrangement and then calculated by the Monte Carlo method. For these calculations a detector model was employed along with a computer algorithm, which seeks agreement between the experimental efficiencies and the calculated ones by automatically determining the parameters of the model. The resulting agreement of the calculated data with the experimental one was within the relative uncertainty of the latter (3-4%) and the parameters of the detector models obtained were close to the values specified by the manufacturers. The detector models thus constructed can then be used for interpolation of calibration curves.
Full energy peak efficiency of NaI(Tl) gamma detectors and its analytical and semi-empirical representations
The validity of various analytical functions and semi-empirical formulae proposed for representing the full energy peak efficiency (FEPE) curves of Ge(Li) and HPGe detectors has been tested for the FEPE of 7.6 cm*7.6 cm and 5 cm*5 cm NaI(Tl) detectors in the gamma energy range from 59.5 to 1408.03 keV. The functions proposed by East (1971), and McNelles and Campbell (1973) provide by far the best representations of the present data. The semi-empirical formula of Mowatt (1969) describes the present data very well. The present investigation shows that some of the analytical functions and semi-empirical formulae, which represent the FEPE of the Ge(Li) and HPGe detectors very well, can be quite fruitfully used for NaI(Tl) detectors.
Validity of various semi-empirical formulae and analytical functions for the efficiency of Ge(Li) detectors
Abstract The validity of various semi-empirical formulae, proposed for representing the full energy peak efficiency, has been tested for 3.0 cm 3 and 4.2 cm 3 Ge(Li) planar detectors in the gamma ray energy range from 59.54 to 1836.13 keV. For a 38 cm 3 coaxial detector the existing analytical functions and a semi-empirical formula have been examined from 319.80 to 2598.80 keV. For planar detectors the semi-empirical formulae of Freeman and Jenkin, and Mowatt give excellent representation of the efficiency in the entire energy range. The eight-parameter function of McNelles and Campbell gives the best results for the 38 cm 3 coaxial detector.