A novel analytical method to calibrate cylindrical side-hole type sodium iodide scintillation detectors

Geometrical and absolute efficiencies play a significant role in the calibration of radioactivity measuring systems, which are regularly complicated. A novel analytical method of efficiency calibration is proposed for cylindrical side-hole type sodium iodide scintillation detectors. Cylindrical side-hole type sodium iodide scintillation detectors have a cylindrical side-hole passing perpendicularly on the sodium iodide crystal axis, which is gathered in the aluminum cover. This detector is a setup for low-level gamma radiation measurement, because of the close 4π solid angle correlated with it, this setup is convenient when low-energy radiation requires efficient detection. Also, the 4π gamma-ray counting is an established way for direct activity measurements and is remarkably well suited for radionuclides with complex gamma-ray spectra. This novel approach depends on the calculation of two primary factors, the photon path length inside the detector active material, and the solid angle, delimited by the radiation source-detector system. In addition, the attenuation of photons by the sodium iodide crystal covering substance is also included by determining the photon path length through this substance. The novel analytical approach calculates the total and geometrical efficiencies of this kind of detector. In comparison, the differences with the published data in the literature indicate that the current approach is favorable in the efficiency measurement of the cylindrical side-hole type sodium iodide scintillation detectors.