A method to calculate the gamma ray detection efficiency of a cylindrical NaI (Tl) crystal

Abstract

Given a wide range application of NaI(Tl) detector in industrial and medical sectors, computation of the related detection efficiency in different distances of a radioactive source, especially for calibration purposes, is the subject of radiation detection studies. In this work, a 2in both in radius and height cylindrical NaI (Tl) scintillator was used, and by changing the radial, axial, and diagonal positions of an isotropic 137 Cs point source relative to the detector, the solid angles and the interaction probabilities of gamma photons with the detector's sensitive area have been calculated. The calculations present the geometric and intrinsic efficiency as the functions of detector's dimensions and the position of the source. The calculation model is in good agreement with experiment, and MCNPX simulation. K: Detector modelling and simulations I (interaction of radiation with matter, interaction of photons with matter, interaction of hadrons with matter, etc); Scintillators, scintillation and light emission processes (solid, gas and liquid scintillators) 1Corresponding author.

Estimation of radioactive activity by gamma spectroscopy

“…By a process of fitting, the The absolute efficiency ε was defined as the ratio between the quanta of radiation detected and those emitted by a sample. This had two contributions: one came from a factor associated with the extension and geometric shape of the instrument, and the other came from the probability that once the quantum of energy entered the sensitive volume of the instrument, it was effectively detected [3,[18][19][20]. They were denoted as the geometric factor G and intrinsic efficiency ε I , respectively.…”

“…where Ω is the solid angle subtended by the detector with respect to the sample. In this case, the sources were considered point sources, and due to the cylindrical shape of the detector, the solid angle was [20].…”