Study the effect of cometary molecules on Gamma-Ray backscattering

Dissertant

Mahdi, Hibah Salim

Thesis advisor

Kazim, Ala Baqir

University

University of Baghdad

Faculty

College of Science

Department

Astronomy and Space Department

University Country

Iraq

Degree

Master

Degree Date

2013

English Abstract

In this research the Compton backscattering technique has been used to calculate the Bulk density of two comets nucleus materials (Encka and Hale – Bopp) at energy 662 keV.

Also, the single scattering model for gamma backscatter densitometer has been used to calculate factors that affect on this technique at energies 60 and 662 keV.

Monte Carlo simulation for the scattering and absorption of photons in semi - infinite bulk material that written in FORTRAN language (77-90) was conducted to study the variation of count rate with source energy, source - detector separation, density, and composition.

It has been noted from the results that only source energies within the “Compton window” are useful for calculating the bulk density because it does not depend on elemental composition.

From the calculating of the variation of count rate with design parameters, the following points were significant:  At energy of 60 keV checks only the gamma attenuation in materials and it appears clearly in materials of high Z and density but the energy at 662 keV could provide the optimum source-detector separation for the density under investigation.

 For a range of energies used in backscatter densitometry, the dominant interaction is the Compton scattering process through photoelectric absorption.

To make an accurate measurement, where the dominant interaction is Compton scattering and to reduce the material chemical composition effect, the source energy must be higher than 400 keV.

Create PDF files without this message by purchasing novaPDF printer (http://www.novapdf.com) For a range of densities, the count rate reaches a maximum at some critical density which depends on the source-detector separation, the source energy and mass attenuation value.

 The composition can be investigated at energy 60 keV and noted that the photoelectric absorption reduces the count rate at high z atomic number for the cometary material that used to be examined.

The purpose of these calculations is to have a good understanding of cometary nucleus material because much of the scientific interest in comets stems from their potential role in explaining the processes responsible for the formation and evolution of the solar system.

Main Subjects

Astronomy

Topics

No. of Pages

169

Table of Contents

Table of contents.

Abstract.

Abstract in Arabic.

Chapter One : General introduction.

Chapter Two : Theoretical background.

Chapter Three : Monte Carlo simulation.

Chapter Four : Results and discussion.

Chapter Five : Conclusions and future work.

References.

American Psychological Association (APA)

Mahdi, Hibah Salim. (2013). Study the effect of cometary molecules on Gamma-Ray backscattering. (Master's theses Theses and Dissertations Master). University of Baghdad, Iraq
https://search.emarefa.net/detail/BIM-604258

Modern Language Association (MLA)

Mahdi, Hibah Salim. Study the effect of cometary molecules on Gamma-Ray backscattering. (Master's theses Theses and Dissertations Master). University of Baghdad. (2013).
https://search.emarefa.net/detail/BIM-604258

American Medical Association (AMA)

Mahdi, Hibah Salim. (2013). Study the effect of cometary molecules on Gamma-Ray backscattering. (Master's theses Theses and Dissertations Master). University of Baghdad, Iraq
https://search.emarefa.net/detail/BIM-604258

Language

English

Data Type

Arab Theses

Record ID

BIM-604258