الفهرس 
Chapter OneOnly 14 pages are availabe for public view
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Abstract
Studying and measuring of gamma-ray energy emitted from radionuclides is very important field of radiation physics, and have many applications in different fields of sciences such as in the study of nuclear structure, the identification of radioisotopes and their activities, estimating absorbed dose, and the determination of interaction cross–sections, in which gamma-rays are either incident or outgoing from the reaction.
The new developments in gamma-ray spectrometry have expanded and have been applied in diverse fields such as astrophysics and medical therapy for which highly accurate measurements of gamma-rays are needed. This has been achieved by way of tracing the interaction of gamma-rays in the semiconductor and scintillation detectors and the energy deposited within.
This thesis is concerned with detector Full Energy Peak Efficiency (FEPE), the peak efficiency assumes that only those interactions that deposit the full energy of the incident radiation are counted, in a differential pulse height distribution, these full energy events are normally evidence by a peak that appears at the highest end of the spectrum. Events that deposit only part of the incident radiation energy then will appear farther to the left in the spectrum. The number of full energy events can be obtained by simply integrating the total area under the peak. The thesis contains five chapters, (79) references, two appendices, plus English and Arabic summaries.
• The First Chapter:
This chapter introduces a general introduction about the interactions of gamma-rays with matter, rationales and types of semiconductor and scintillation detectors and modes of action of ionized radiation in them. Special emphasis is given to germanium and sodium iodide detectors and associated auxiliary equipment to carry out the measurements. In addition, applications of gamma-ray spectroscopy are considered.
• The Second Chapter:
This chapter is devoted to definitions and explanations of different detector efficiencies, and we will discuss the different factors which affect the detector efficiency determination, and the discussion of the various methods used to determine those efficiencies (Experimental, Monte Carlo, Semi-empirical, Efficiency transfer and the Direct Mathematical) methods, we will focus on the last theoretical method as it is the basis of the new [Numerical Simulation Method (NSM)] for different source-detector geometries as described briefly in chapter three. Besides mentioning some details about the efficiency transfer method.
• The Third Chapter:
In this chapter, a new analytical approach for calculation of the full-energy peak efficiency of the co-axial and non-axial detector with respect to point and volumetric sources (cylindrical and spherical) is presented. This approach depends on two main factors; first is the accurate analytical calculation of the average path length covered by the photon in each of the following: the detector active volume, the the source matrix, the source container, the dead layer and the end cap of the detector, second is the effective solid angle between the different sources andthe detector configuration Ωeff to use it in the ETM rule.
• The Fourth Chapter:
In this chapter, we will describe the calibration process of gamma-ray applications in the spectroscopy field, showing how the experimental technique was performed at Prof. Dr. Younis. S. Selim Radiation Physics laboratory. Moreover, this chapter contains a brief description of the setup parameters of the detector used and supported with the (serial & model) number, the details of the point and volumetric standard sources used in measurement process are also mentioned. Short description for using Genie 2000 data acquisition and analysis software made by Canberra in spectrum acquisition, spectrum analysis and data management. Short description for using the collecting spectrum software (winTMCA32 software made by ICx Technologies).
• The Fifth Chapter:
In this chapter, some experimental data are included, as well as the comparisons of our proposed [the efficiency transfer theoretical method] for calculating the different efficiencies with the measured and calculated values by the efficiency transfer method, these comparisons include the comparisons of 152Eu aqueous radioactive source placed in different vial shapes (cylindrical and spherical) with HPGe and NaI (Tl) detectors. Remarkably excellent agreements are clearly noticed between the measured values with the calculations values obtained using the present efficiency transfer theoretical method.
• The Appendix I
This appendix contains the basic programs for effective solid angle calculations for point and volumetric sources.
• The Appendix II
This appendix contains the list of publications.
I will describe briefly the contents of this thesis, how it presents a theoretical approach that can be used for gamma-ray tracing in both (NaI scintillation detector and HPGe detector). Using this theoretical approach one can calculate the efficiency of scintillation detector for radioactive volumetric sources of dimensions larger or smaller than the detector, placed axial and non-axial from the detector, which based on a series of point sources. Experimental results measured at different positions using the Efficiency Transfer principle, and also we will compare it with the experimental results. The results in chapter five show that the present approach can be extended in future for modern detection systems, where there are several other methods usually used to determine the detectors efficiencies, these methods are as the following
• The Experimental Method:
This method needs a variety of sources with different energies in the domain of interest and having the same shape and geometrical solid angle of the samples under investigation.
• The Empirical Method:
This method is based on the interpolations or extrapolations to meet with the gamma-ray energy and geometrical solid angle of interest.
• The Monte Carlo method:
This method treats the incident gamma-ray photons in a one by one order, which needs a large number of events to overcome the statistical fluctuation.
• The Efficiency Transfer Method:
This method based on knowing the change in efficiency under conditions of measurement different from those of calibration, which can be determined on the basis of variation of the geometrical parameters of the source-detector arrangement (the ratio of the effective solid angles).
• The Direct Mathematical Method:
This method based on the source-detector configuration. The mathematical expressions are sets of well-defined integrals, which are easily programmed and being computed using the numerical method, where in this last theoretical method, for total efficiency, εT, the calculations are straightforward by considering the total attenuation coefficient, μT, of the detector’s material [HPGe or Na(TI)], which is the total sum of the different interaction cross sections within the detector active volume (the photoelectric effect, the Compton effect and pair production cross section). On the other hand, for the full-energy peak efficiency, εP, the calculations of the full-energy peak attenuation coefficient, μP, which is the sum of (the photoelectric plus fractional from Compton scattering and pair production cross section) which leads to the maximum peak in the detector spectrum, is to be considered. These, beside a new analytical approach to calculate the full-energy peak efficiency of co-axial semiconductor detectors, including (the source self-attenuation correction, the attenuation by the source container and the detector housing materials) by analytical calculation of the average path length covered by the photon in each of the following: the detector active volume, the source matrix, the source container, the dead layer and the end cap of the detector.