Non-destructive methods of material interrogation are used to locate hidden explosives and thwart terrorism attempts. In one such method materials are bombarded with neutrons which react with the nuclei of the atoms within causing a de-excitation process emitting a gamma-ray. The spectrum displayed by the collection of these gamma-rays gives valuable information regarding the material’s elemental make-up. It has been hypothesized that gamma-rays from neutron-induced gamma-ray reactions on light elements with atomic numbers less than 20, including most of the gamma-rays of interest in explosives detection, are Doppler-broadened. This thesis focuses on the gamma ray spectra from the 4438 keV gamma ray in the 12C (n, n’γ) reaction wherein Doppler broadening was investigated. A graphite sample was exposed to 14 MeV neutrons and the 12C gamma ray spectra collected using an HPGe detector positioned at four different angles with respect to the neutron beam; near 00, 450, 900 and 1350. No other experimental parameter was changed. The resultant gamma ray spectra indicated Doppler broadening had occurred.
","abstract_html":"<p>Non-destructive methods of material interrogation are used to locate hidden explosives and thwart terrorism attempts. In one such method materials are bombarded with neutrons which react with the nuclei of the atoms within causing a de-excitation process emitting a gamma-ray. The spectrum displayed by the collection of these gamma-rays gives valuable information regarding the material’s elemental make-up. It has been hypothesized that gamma-rays from neutron-induced gamma-ray reactions on light elements with atomic numbers less than 20, including most of the gamma-rays of interest in explosives detection, are Doppler-broadened. This thesis focuses on the gamma ray spectra from the 4438 keV gamma ray in the 12C (n, n’γ) reaction wherein Doppler broadening was investigated. A graphite sample was exposed to 14 MeV neutrons and the 12C gamma ray spectra collected using an HPGe detector positioned at four different angles with respect to the neutron beam; near 00, 450, 900 and 1350. No other experimental parameter was changed. The resultant gamma ray spectra indicated Doppler broadening had occurred.</p>","abstract_has_math":false,"creators":["Whitfield, Melinda D."],"institution":null,"degree_name":"Master of Science Homeland Security Sciences","degree_level":null,"degree_discipline":"Department of Physics and Astronomy","degree_department":null,"school":null,"contributors":["Dr. Phil Womble (Director), Dr. Keith Andrew, Dr. Alexander Barzilov"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2010,"date_issued":"2010-12-01T08:00:00Z","date_published":"2010-12-01T08:00:00Z","updated_at":"2026-07-24T06:08:09Z","subjects":["explosives detection","non-destructive analysis","neutron interrogation","Atomic, Molecular and Optical Physics","Defense and Security Studies"],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://digitalcommons.wku.edu/theses/1075","outbound_label":"Repository record","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Dr. Phil Womble (Director), Dr. Keith Andrew, Dr. Alexander Barzilov"]},{"key":"dc:creator","label":"Author","values":["Whitfield, Melinda D."]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:type","label":"Dc Type","values":["Thesis"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Department of Physics and Astronomy"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Master of Science Homeland Security Sciences"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["explosives detection","non-destructive analysis","neutron interrogation","Atomic, Molecular and Optical Physics","Defense and Security Studies"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://digitalcommons.wku.edu/theses/1075"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["Non-destructive methods of material interrogation are used to locate hidden explosives and thwart terrorism attempts. In one such method materials are bombarded with neutrons which react with the nuclei of the atoms within causing a de-excitation process emitting a gamma-ray. The spectrum displayed by the collection of these gamma-rays gives valuable information regarding the material’s elemental make-up. It has been hypothesized that gamma-rays from neutron-induced gamma-ray reactions on light elements with atomic numbers less than 20, including most of the gamma-rays of interest in explosives detection, are Doppler-broadened. This thesis focuses on the gamma ray spectra from the 4438 keV gamma ray in the 12C (n, n’γ) reaction wherein Doppler broadening was investigated. A graphite sample was exposed to 14 MeV neutrons and the 12C gamma ray spectra collected using an HPGe detector positioned at four different angles with respect to the neutron beam; near 00, 450, 900 and 1350. No other experimental parameter was changed. The resultant gamma ray spectra indicated Doppler broadening had occurred.
"]},{"key":"dc:title","label":"Title","values":["Doppler-Broadening of Light Nuclei Gamma-Ray Spectra"]}]}],"canonical_facts":{"dc:contributor":["Dr. Phil Womble (Director), Dr. Keith Andrew, Dr. Alexander Barzilov"],"dc:creator":["Whitfield, Melinda D."],"dc:description.abstract":["Non-destructive methods of material interrogation are used to locate hidden explosives and thwart terrorism attempts. In one such method materials are bombarded with neutrons which react with the nuclei of the atoms within causing a de-excitation process emitting a gamma-ray. The spectrum displayed by the collection of these gamma-rays gives valuable information regarding the material’s elemental make-up. It has been hypothesized that gamma-rays from neutron-induced gamma-ray reactions on light elements with atomic numbers less than 20, including most of the gamma-rays of interest in explosives detection, are Doppler-broadened. This thesis focuses on the gamma ray spectra from the 4438 keV gamma ray in the 12C (n, n’γ) reaction wherein Doppler broadening was investigated. A graphite sample was exposed to 14 MeV neutrons and the 12C gamma ray spectra collected using an HPGe detector positioned at four different angles with respect to the neutron beam; near 00, 450, 900 and 1350. No other experimental parameter was changed. The resultant gamma ray spectra indicated Doppler broadening had occurred.
"],"dc:identifier":["https://digitalcommons.wku.edu/theses/1075"],"dc:subject":["explosives detection","non-destructive analysis","neutron interrogation","Atomic, Molecular and Optical Physics","Defense and Security Studies"],"dc:title":["Doppler-Broadening of Light Nuclei Gamma-Ray Spectra"],"dc:type":["Thesis"],"thesis:degree_discipline":["Department of Physics and Astronomy"],"thesis:degree_name":["Master of Science Homeland Security Sciences"]},"updated_at":"2026-07-24T06:08:09Z"}