The development of a CsI(TI)-photodiode array for remote geochemical analysis
The development of a CsI(TI)-photodiode array for remote geochemical analysis
To improve our understanding of the mechanism of the formation of the Solar System, information is needed on the global chemical composition of the planets outside of the Earth-Moon system. Thus, the measurement of the chemical composition of Mars and Mercury is a high priority for both the ESA and NASA space programmes. Remote geochemical analysis (RGA), by neutron activation gamma-ray spectroscopy, is a proven technique for remotely mapping the chemical composition of a planet with a thin or no atmosphere and as a result future missions to other terrestrial planets will probably include a gamma-ray spectrometer.
The spectrometer must have sufficient sensitivity to resolve the most important emission lines radiating from the planet, whilst remaining within the mass, power and budget limitations of the mission specification. Therefore, there is a requirement for a spectrometer that will provide sufficient sensitivity, to determine the ratio's of elements such as Fe, O, Si and the naturally occurring radionucides K, U and Th, without incurring the high costs of a cooled HPGe detector.
This work considers the factors that will determine the sensitivity of a scintillator gamma-ray spectrometer for RGA and demonstrates that a 61 element, pixelated, GsI(T1)-photodiode array will have a greater sensitivity than an, equivalent mass, NaI(Tl)-PMT or BGO-PMT detector. This is a result of the high mass ratio of sensitive material in the CsI(Tl)-photodiode array and the improved energy resolution, when compared to a NaI(Tl)-PMT detector, at energies above 2MeV. A prototype 7-element array has been designed, constructed and, tested at energies up to 4.44MeV, to demonstrate the potential performance of a larger 61-element array. The energy resolution of the 7 element array was found to be 2.93% FWHM at 4.44MeV, when operating in simple summation mode, which compares to 3.5% FWHM for a 2" NaI(Tl)-PMT detector.
University of Southampton
Evans, Robert James
53ab35f3-bc11-44fd-ad0c-923bdb7c0891
1999
Evans, Robert James
53ab35f3-bc11-44fd-ad0c-923bdb7c0891
Evans, Robert James
(1999)
The development of a CsI(TI)-photodiode array for remote geochemical analysis.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
To improve our understanding of the mechanism of the formation of the Solar System, information is needed on the global chemical composition of the planets outside of the Earth-Moon system. Thus, the measurement of the chemical composition of Mars and Mercury is a high priority for both the ESA and NASA space programmes. Remote geochemical analysis (RGA), by neutron activation gamma-ray spectroscopy, is a proven technique for remotely mapping the chemical composition of a planet with a thin or no atmosphere and as a result future missions to other terrestrial planets will probably include a gamma-ray spectrometer.
The spectrometer must have sufficient sensitivity to resolve the most important emission lines radiating from the planet, whilst remaining within the mass, power and budget limitations of the mission specification. Therefore, there is a requirement for a spectrometer that will provide sufficient sensitivity, to determine the ratio's of elements such as Fe, O, Si and the naturally occurring radionucides K, U and Th, without incurring the high costs of a cooled HPGe detector.
This work considers the factors that will determine the sensitivity of a scintillator gamma-ray spectrometer for RGA and demonstrates that a 61 element, pixelated, GsI(T1)-photodiode array will have a greater sensitivity than an, equivalent mass, NaI(Tl)-PMT or BGO-PMT detector. This is a result of the high mass ratio of sensitive material in the CsI(Tl)-photodiode array and the improved energy resolution, when compared to a NaI(Tl)-PMT detector, at energies above 2MeV. A prototype 7-element array has been designed, constructed and, tested at energies up to 4.44MeV, to demonstrate the potential performance of a larger 61-element array. The energy resolution of the 7 element array was found to be 2.93% FWHM at 4.44MeV, when operating in simple summation mode, which compares to 3.5% FWHM for a 2" NaI(Tl)-PMT detector.
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Published date: 1999
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Local EPrints ID: 463912
URI: http://eprints.soton.ac.uk/id/eprint/463912
PURE UUID: 75d78fac-353a-4e42-a82a-694d4bb8df26
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Date deposited: 04 Jul 2022 20:58
Last modified: 16 Mar 2024 19:06
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Author:
Robert James Evans
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