| Summary: | This work deals with full-energy peak efficiency for a counting array of two
NaI(Tl) scintillation detectors (2"x 2" and 3" x 3" with 7.5% and 8.5%
resolutions, respectively) and radioactive sources in the form of rectangular
parallelepipeds of various dimensions. Aqueous solutions containing the 152Eu
radionuclide were used; the latter exhibits a favourable multiline gamma
spectrum covering a wide energy range from121.78 keV up to 1408.03 keV. A new
mathematical and analytical approach to the problem is developed. The well
known, accurate and widely used efficiency transfer principle is applied,
together with detector efficiency calculations based on the effective solid
angle concept. The self-attenuation of the source matrix, attenuation by the
source container and detector housing materials, as well as a number of other
relevant details of the experimental set-up were duly accounted for. A
remarkable agreement between the measured and calculated efficiencies was
observed for a variety of source-to-detectors distances, confirming the
reliability of the method developed.
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