الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Gamma spectroscopy is a non-destructive and analytical technique that is used to distinguish between various radioactive isotopes in a sample “element analysis.” It is also an important tool when studying the properties of excited nuclei and their gamma emissions. In gamma spectroscopy, the energy of an unknown incident gamma-rays is absorbed by a detector. If the detector is characterized, the gamma source of an unknown sample can be identified, and its concentration can be estimated. Well-type detectors, with comparison to cylindrical detectors, maximize the probability of absorption of radiation from a sample by their approximately 4𝜋 geometry. Well-type detectors play a significant role in qualitative and quantitative analysis of low-activity samples due to their noticeably high efficiency. The high efficiency of well-detectors also makes them an ideal choice when dealing with very low activity sources. Determining the detector’s efficiency is essential to characterize a detector in addition to energy calibration and energy resolution. Energy calibration helps identify the elements present in any unknown sample, while the detector efficiency helps determine the percentage of these elements in the sample. In addition, determining the detector’s energy resolution provides evidence of the detectors’ ability to distinguish gamma-rays with close energies. This can be accomplished experimentally or computed by Monte Carlo simulation. In this work, a Ø123x152mm NaI(Tl) well-type detector was characterized by determining its efficiency and resolution curves for different source energies and source locations. The characterization was performed using a Monte Carlo code, MCNP5, and its validation was ensured by comparison to experimental data. The MCNP5 simulated results agreed with the theoretical theories; however, in order to be able to compare these results with the experiment, the simulated results were broadened using a MATLAB code. The experimental and broadened simulation spectra were very close, indicating the validity of the MCNP5 and MATLAB in simulating the detector’s efficiency and resolution curves at any geometry. Experimentally, the efficiency results for any source location shows that, in the low energy region, the efficiency increased as the energy increased, while in the high energy region, the efficiency decreased as the energy increased. For resolution, the results showed better resolution as the energy increased. At the Detector’s top, the resolution was 23.14% at 59.54 KeV and 6.44 at 1115.54 KeV. When the source location changed from the detector’s bottom upwards, its efficiency decreased, and its resolution improved. The validated MCNP5 and MATLAB code can be effectively used to model the well detector, especially when weak radioactive sources are in question. This simulation is timesaving with respect to experimental approaches as it allows examining different setups without background effects that complicate response functions. It can also deal with a variety of energies nearly impossible to achieve experimentally.