New mathematical approach to calculate the geometrical efficiency using different radioactive sources with gamma-ray cylindrical shape detectors

Thabet, Abouzeid A.,Hamzawy, A.,Badawi, Mohamed S. Korean Nuclear Society 2020 Nuclear Engineering and Technology Vol.52 No.6

The geometrical efficiency of a source-to-detector configuration is considered to be necessary in the calculation of the full energy peak efficiency, especially for NaI(Tl) and HPGe gamma-ray spectroscopy detectors. The geometrical efficiency depends on the solid angle subtended by the radioactive sources and the detector surfaces. The present work is basically concerned to establish a new mathematical approach for calculating the solid angle and geometrical efficiency, based on conversion of the geometrical solid angle of a non-axial radioactive point source with respect to a circular surface of the detector to a new equivalent geometry. The equivalent geometry consists of an axial radioactive point source with respect to an arbitrary elliptical surface that lies between the radioactive point source and the circular surface of the detector. This expression was extended to include coaxial radioactive circular disk source. The results were compared with a number of published data to explain how significant this work is in the efficiency calibration procedure for the γ-ray detection systems, especially in case of using isotropic radiating γ-ray sources in the form of point and disk shapes.

Analytical-numerical formula for estimating the characteristics of a cylindrical NaI(Tl) gamma-ray detector with a side-through hole

Thabet Abouzeid A.,Badawi Mohamed S. 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.10

NaI(Tl) scintillation materials are considered to be one of many materials that are used exclusively for gray detection and spectroscopy. The gamma-ray spectrometer is not an easy-to-use device, and the accuracy of the numerical values must be carefully checked based on the rules of the calibration technique. Therefore, accurate information about the detection system and its effectiveness is of greater importance. The purpose of this study is to estimate, using an analytical-numerical formula (ANF), the purely geometric solid angle, geometric efficiency, and total efficiency of a cylindrical NaI(Tl) g-ray detector with a side-through hole. This type of detector is ideal for scanning fuel rods and pipelines, as well as for performing radio-immunoassays. The study included the calculation of the complex solid angle, in combination with the use of various points like gamma sources, located axially and non-axially inside the through detector side hole, which can be applied in a hypothetical method for calibrating the facility. An extended g-ray energy range, the detector, source dimensions, “source-to-detector” geometry inside the side-through hole, path lengths of g-quanta photons crossing the facility, besides the photon average path length inside the detector medium itself, were studied and considered. This study is very important for an expanded future article where the radioactive point source can be replaced by a volume source located inside the side-trough hole of the detector, or by a radioactive pipeline passing through the well. The results provide a good and useful approach to a new generation of detectors that can be used for lowlevel radiation that needs to be measured efficiently.

STUDY ON THE EFFECT OF THE SELF-ATTENUATION COEFFICIENT ON γ-RAY DETECTOR EFFICIENCY CALCULATED AT LOW AND HIGH ENERGY REGIONS

El-Khatib, Ahmed M.,Thabet, Abouzeid A.,Elzaher, Mohamed A.,Badawi, Mohamed S.,Salem, Bohaysa A. Korean Nuclear Society 2014 Nuclear Engineering and Technology Vol.46 No.2

The present work used the efficiency transfer method used to calculate the full energy peak efficiency (FEPE) curves of the (2"*2" & 3"*3") NaI (Tl) detectors based on the effective solid angle subtended between the source and the detector. The study covered the effect of the self attenuation coefficient of the source matrix (with a radius greater than the detector's radius) on the detector efficiency. $^{152}$ An Eu aqueous radioactive source covering the energy range from 121.78 keV up to 1408.01 keV was used. In this study an empirical formula was deduced to calculate the difference between the measured and the calculated efficiencies [without self attenuation] at low and high energy regions. A proper balance between the measured and calculated efficiencies [with self attenuation] was achieved with discrepancies less than 3%, while reaching 39% for calculating values [without self attenuation] due to working with large sources, or for low photon energies.

Study on the Effect of the Self-Attenuation Coefficient on γ-ray Detector Efficiency Calculated at Low and High Energy Regions

Ahmed. M. El-Khatib,ABOUZEID. A. THABET,MOHAMED. A. ELZAHER,MOHAMED. S. BADAWI,BOHAYSA. A. SALEM 한국원자력학회 2014 Nuclear Engineering and Technology Vol.46 No.2

The present work used the efficiency transfer method used to calculate the full energy peak efficiency (FEPE) curves ofthe (2"*2" & 3"*3") NaI (Tl) detectors based on the effective solid angle subtended between the source and the detector. Thestudy covered the effect of the self attenuation coefficient of the source matrix (with a radius greater than the detector's radius)on the detector efficiency. 152 An Eu aqueous radioactive source covering the energy range from 121.78 keV up to 1408.01keV was used. In this study an empirical formula was deduced to calculate the difference between the measured and thecalculated efficiencies [without self attenuation] at low and high energy regions. A proper balance between the measured andcalculated efficiencies [with self attenuation] was achieved with discrepancies less than 3%, while reaching 39% forcalculating values [without self attenuation] due to working with large sources, or for low photon energies.

Calibration of cylindrical NaI(Tl) gamma-ray detector intended for truncated conical radioactive source

Mohamed S. Badawi,Abouzeid A. Thabet 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.4

The computation of the solid angle and the detector efficiency is considering to be one of the mostimportant factors during the measuring process for the radioactivity, especially the cylindrical g-rayNaI(Tl) detectors nowadays have applications in several fields such as industry, hazardous for health,the gamma-ray radiation detectors grow to be the main essential instruments in radiation protectionsector. In the present work, a generic numerical simulation method (NSM) for calculating the efficiencyof the g-ray spectrometry setup is established. The formulas are suitable for any type of source-todetector shape and can be valuable to determine the full-energy peak and the total efficiencies andP/T ratio of cylindrical g-ray NaI(Tl) detector setup concerning the truncated conical radioactivesource. This methodology is based on estimate the path length of g-ray radiation inside the detectoractive medium, inside the source itself, and the self-attenuation correction factors, which typically useto correct the sample attenuation of the original geometry source. The calculations can be completedin general by using extra reasonable and complicate analytical and numerical techniques than thestandard models; especially the effective solid angle, and the detector efficiency have to be calculatedin case of the truncated conical radioactive source studied condition. Moreover, the (NSM) can be usedfor the straight calculations of the g-ray detector efficiency after the computation of improvement thatneed in the case of g-g coincidence summing (CS). The (NSM) confirmation of the development createdby the efficiency transfer method has been achieved by comparing the results of the measuringtruncated conical radioactive source with certified nuclide activities with the g-ray NaI(Tl) detector,and a good agreement was obtained after corrections of (CS). The methodology can be unlimited tofind the theoretical efficiencies and modifications equivalent to any geometry by essential sufficientlythe physical selective considered situation.