The development of a position sensitive gamma-ray detector
The development of a position sensitive gamma-ray detector
This thesis describes the development and technical evaluation of a novel two-dimensional position sensitive scintillation device, operating from 500 keV to 2 MeV. This concept has evolved from the earlier design of the one-dimensional position sensitive bar. An equilateral triangle of scintillator material is used with photosensitive devices coupled to the corners, with the gamma-ray photon interaction location, in two dimensions, determined from the relative amplitudes of the three observed signals.
The optimum combination of detector area and thickness, readout device and scintillation material for a prototype was determined with the aid of optical and gamma-ray Monte-Carlo simulations. The prototype CsI detector, an equilateral triangle of 10 cm side length with photodiodes as readout devices, was tested with radioactive sources and was found to have a spatial resolution of 1.5 cm (1σ) and an energy resolution of 15 % (FWHM) at 662 keV. As a result of a detailed analysis of the experimental data and computer modelling the design for a revised configuration was determined. The modified detector is an equilateral triangle of side length 20 cm, with photomultiplier tubes for readout and has a predicted spatial resolution 1.1 cm (1σ) and energy resolution 7 % (FWHM) at 662 keV.
One possible use for such a position-sensitive detector is in the construction of an All Sky Monitor. Tessellating the triangles together to form an icosahedron offers 4π coverage for the detection of gamma-rays and identification of rapid transient features such as gamma-ray bursts. The instrument operates by reconstructing events caused by an incident gamma-ray photon Compton scattering between any two of the available detector modules. The method of backprojection can then be applied to reconstruct the sky location of point sources with various energies. The sensitivity of the instrument, whilst in a low earth orbit, was also evaluated using further Monte-Carlo simulations. After consideration of the many factors that contribute to the reconstruction of a cosmic point source, an angular resolution of 13° (FWHM) and a continuum sensitivity of 2x10-7 counts cm-2s-1keV-1 at 1 MeV was derived. This compares well with existing pointed telescope systems and has the added benefit of all sky coverage.
University of Southampton
Lawton, Christopher David
1998
Lawton, Christopher David
Lawton, Christopher David
(1998)
The development of a position sensitive gamma-ray detector.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
This thesis describes the development and technical evaluation of a novel two-dimensional position sensitive scintillation device, operating from 500 keV to 2 MeV. This concept has evolved from the earlier design of the one-dimensional position sensitive bar. An equilateral triangle of scintillator material is used with photosensitive devices coupled to the corners, with the gamma-ray photon interaction location, in two dimensions, determined from the relative amplitudes of the three observed signals.
The optimum combination of detector area and thickness, readout device and scintillation material for a prototype was determined with the aid of optical and gamma-ray Monte-Carlo simulations. The prototype CsI detector, an equilateral triangle of 10 cm side length with photodiodes as readout devices, was tested with radioactive sources and was found to have a spatial resolution of 1.5 cm (1σ) and an energy resolution of 15 % (FWHM) at 662 keV. As a result of a detailed analysis of the experimental data and computer modelling the design for a revised configuration was determined. The modified detector is an equilateral triangle of side length 20 cm, with photomultiplier tubes for readout and has a predicted spatial resolution 1.1 cm (1σ) and energy resolution 7 % (FWHM) at 662 keV.
One possible use for such a position-sensitive detector is in the construction of an All Sky Monitor. Tessellating the triangles together to form an icosahedron offers 4π coverage for the detection of gamma-rays and identification of rapid transient features such as gamma-ray bursts. The instrument operates by reconstructing events caused by an incident gamma-ray photon Compton scattering between any two of the available detector modules. The method of backprojection can then be applied to reconstruct the sky location of point sources with various energies. The sensitivity of the instrument, whilst in a low earth orbit, was also evaluated using further Monte-Carlo simulations. After consideration of the many factors that contribute to the reconstruction of a cosmic point source, an angular resolution of 13° (FWHM) and a continuum sensitivity of 2x10-7 counts cm-2s-1keV-1 at 1 MeV was derived. This compares well with existing pointed telescope systems and has the added benefit of all sky coverage.
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Published date: 1998
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Local EPrints ID: 463450
URI: http://eprints.soton.ac.uk/id/eprint/463450
PURE UUID: e4e704d7-46a1-4a5a-b871-4451408f70d8
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Date deposited: 04 Jul 2022 20:52
Last modified: 04 Jul 2022 20:52
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Author:
Christopher David Lawton
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