الفهرس 
acknowledgmentOnly 14 pages are availabe for public view
 |  | from | 16 |  |  |
| | | from | 16 | | |
Abstract
Studying and measuring of gamma-ray energy emitted from radionuclides is a 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.
The 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 of 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 four chapters, (78) references, English and Arabic
summaries.
The First Chapter:
This chapter introduces a general introduction about the interactions of gamma-rays
with matter, and the modes of action of ionized radiation in it, and studying the detection
mechanism. Special emphasis is given to sodium iodide scintillation 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, Also 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
ii
Mathematical) methods, beside all of that, the chapter focus on the last theoretical method as
it is the basis of the new [Numerical Simulation Method (NSM)] for different sourcedetector
geometries as described briefly in this chapter .
In this chapter, a new numerical simulation method was introduced using sets of analytical
formula based on the theoretical approach (Direct Mathematical Method) proposed by
several authors previously to calculate the effective solid angle between the different
radioactive sources and the detector configuration. More over calculation the efficiency of
NaI (Tl) detector were extended using parallelepiped radioactive source with dimensions
less than the face area of the detector.
The Third Chapter:
In this chapter , the calibration process of gamma-ray detector was described and 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 by the (serial & model) number, the details of the point and
volumetric standard radioactive sources used in measurement process are also mentioned.
Beside the short description for using Genie 2000 data acquisition and analysis software
made by Canberra in spectrum acquisition, spectrum analysis and data management was
given. Also, short description for using the collecting spectrum software (winTMCA32
software made by ICx Technologies) was given.
The Fourth Chapter:
In this chapter, the experimental data were presented, as well as the comparisons between
the calculating full-energy peak efficiency (FEPE) values, calculated by the efficiency
transfer method (ET) and the measured ones. These comparisons include the comparisons of
different sources with NaI(Tl) 3x3 detector. Remarkably excellent agreements are clearly
noticed between the measured values with calculated values obtained using the present
efficiency transfer theoretical method. Using this theoretical approach one can calculate the
efficiency of scintillation detector for using radioactive parallelepiped sources depending on
a series of point sources that measured at different positions from the detector. The results in
chapter four show that the present approach can be extended in future for modern detection
systems. And contain the conclusions drawn out of the presented thesis.