Studying the interaction of continuous energy gamma-ray in different materials

Other Title(s)

دراسة تفاعل فوتونات أشعة كاما ذات الطاقة المستمرة في أوساط مختلفة

Dissertant

Lutfi, Nabil Fawzi

Thesis advisor

al-Zubaydi, Ali Abd al-Latif Karim

Comitee Members

Kazim, A. A.
Muhammad, Karim K.
Dakhil, Zahidah Ahmad

University

University of Baghdad

Faculty

College of Science

Department

Department of Physics

University Country

Iraq

Degree

Master

Degree Date

2011

English Abstract

The mass attenuation coefficients, total atomic and electronic interaction cross-sections, mean free path, effective atomic, electronic numbers of pure elements, compounds and alloys absorbers of various thicknesses, which have been investigated for a continuous energy gammaray that emitted by optimum intensity using lead target, and excited by 90Sr/90Y beta emitter with (Emax=2.274 MeV).

The calculated values were obtained from the continuous energy gamma-ray (bremsstrahlung) spectra recorded with different targets using a multichannel NaI (Tl) scintillation spectrometer under narrow beam particular geometrical set-up in the energy region of 0.08-1.6 MeV.

Coefficients obtained for the investigated samples increase with increase of Z values of the target and decrease with the increasing of the photon energy.

For concrete samples it was found that concrete reinforced with 3% Pb has the higher coefficient and shields more gamma-ray beams than the concrete-3% Fe3C and pure concrete.

The effective atomic numbers and electron densities have been determined on the basis of mixture rule using (winXcom) program.

Results of mass attenuation coefficients and interaction cross-sections are in good agreement with the theoretical values calculated using (winXcom) program.

Metallic absorbers are found to act as energy filters and change the shape of the transmitted continuous energy gamma-ray spectrum due to decrease of the mass attenuation coefficients with increase in absorber thickness.

This is unlike the attenuation of monoenergetic gamma ray which is independent of the absorber thickness.

This confirms that the attenuation of continuous energy gamma-ray in an absorber dose not conform to a single exponential law.

III Rather it is a combination of a large number of exponential terms.

This is due to the continuous nature of the bremsstrahlung spectrum.

The mechanisms involved in mass energy transfer (μ????⁄??) and mass energy absorption (μ???? ⁄??) in an absorber irradiated with an external photon beam have been also investigated in this work.

μ????⁄?? values were determined in Al, Fe, Cu, Ag and Pb elements using mathematical equations for an incident energy range between 0.001 MeV and 100 MeV.

It has been found that the mean energy transfer fraction by photoelectric effect ??????? ? depends not only on photon energy ℎ?? but also on the atomic number Z of the absorber atom, while the mean energy transfer fraction by Compton scattering and pair production interactions (???? and ??????) depend only on photon energy ℎ??.

Further these coefficients were compared with the μ⁄??.

It has been found that the μ????⁄?? equal to the μ⁄?? when the mean energy transfer fraction (??̅ ???? )= 1.

The μ???? ⁄?? coefficients were also calculated using (XMuDat) program and the comparison with μ⁄?? were also illustrated.

Main Subjects

Physics

No. of Pages

130

Table of Contents

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Language

English

Data Type

Arab Theses

Record ID

BIM-606430