Explosives detection using nuclear analytical methods

Vrcelj, Gregor (2014) Explosives detection using nuclear analytical methods. Diploma thesis, Faculty of Science > Department of Physics.

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Explosives detection using nuclear analytical methods is an importan addition to landmine clearence devices because it enables determination of chemical compositon characteristics of interogated objects. Neutron and gamma radiation possess outstanding matter-penetrating properties which enable excellent characterisation of objects burried into soil. Still, success of any method depends on realistic conditions found in the environment in which we intend to apply this method. When detecting explosives in soil environment, one of it's most important properties to consider is soil humidity. In this thesis we are going to use associated alpha-particle technique to test the capabilites of two scintilation detectors, first one based on bismuth germanate and second one based on lanthanium bromide. Using said detectors, we will to attempt to detect anti-personel mine replica burried into soil of different humidites. Associated alpha-particle technique enables electronic collimation of 14.1 MeV neutron beam originating from D-T reaction. Neutrons are emitted into known spatial angle and cause excitation upon innelastic collisions with the observed target nuclei. Chemical composition characteristics are determined by analyzing measured gamma spectra from A(n,n'γ)A reactions. Backgroud reduction of spectra is executed by measuring neutron time of flight to target which gives us time spectrum of events, and that is one of the most important features of this technique. Elements whose presence we can detect, and which are interesting in the context of this thesis, are: carbon, oxygen, nitrogen, hydrogene, aluminum, silicium.. In order to confirm presence of explosives in this thesis we will measure carbon content and we shall observe oxygen and hydrogen content in respect to changing humidity of the soil sample. Measurements were done in seven serieses for seven different soil humidites. In each series spectra of soil with and without burried mine were observed. Each measurment series was done using both BGO and LaBr3:Ce detectors. Lastly, performance of detectors was compared.

Item Type: Thesis (Diploma thesis)
Keywords: nuclear analytical method, explosives detection, scintilation detectors
Supervisor: Sudac, Davorin
Date: 30 September 2014
Number of Pages: 71
Subjects: NATURAL SCIENCES > Physics
Divisions: Faculty of Science > Department of Physics
Depositing User: Gordana Stubičan Ladešić
Date Deposited: 09 Dec 2014 14:20
Last Modified: 20 Jan 2017 12:57
URI: http://digre.pmf.unizg.hr/id/eprint/3489

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