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A study of the validity of the efficiency transfer method to calculate the peak efficiency using γ-ray detectors at extremely large distances



AbstractThe full-energy peak efficiency (FEPE) curves of the (2″ × 2″ and 3″ × 3″) NaI (Tl) detectors were measured at seven different axial positions from their surfaces. The calibration process was done using radioactive point sources, which produce a wide energy range from 59.53 up to 1,408.01 keV. This work has been undertaken to explain the effects of source energy and sourcE−to-detector distance on the detector efficiency calculations. The study provides an empirical formula to calculate FEPE based on the efficiency transfer method for different detectors using the effective solid angle ratio at very large distances and for higher energies. A remarkable agreement between the measured and calculated efficiencies for the detectors at the sourcE−to-detector distances