Detection of gamma-ray polarisation using the integral satellite
Detection of gamma-ray polarisation using the integral satellite
There have been few attempts at measuring gamma-ray polarisation since measurements are hampered by large backgrounds and systematic effects within the detectors. However, the advent of modern fast computing clusters has made large scale simulation of an instrument’s response now possible. By combining instrument data and results from detailed Monte-Carlo Mass-Model simulations using GEANT 4, it is possible to put constraints on the polarisation characteristics of the gamma-ray flux emitted by a source. Using the Compton scattered events in the SPI instrument on INTEGRAL, constraints have been put on the percentage polarisation in the prompt gamma-ray flux of GRB041219a to be 96±40% at 68% confidence and greater than 5% at 99.7% confidence. The method has also been extended to allow the summation of multiple data sets to obtain a measurement of the off-pulse polarisation of the Crab pulsar of 46% ± 10% at an angle of 123° ± 11°, showing a remarkable alignment to the rotational axis of the spinning Neutron star.
University of Southampton
Clark, David John
7ae6237c-d8cb-4310-98b5-100dd0e5aeee
2007
Clark, David John
7ae6237c-d8cb-4310-98b5-100dd0e5aeee
Clark, David John
(2007)
Detection of gamma-ray polarisation using the integral satellite.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
There have been few attempts at measuring gamma-ray polarisation since measurements are hampered by large backgrounds and systematic effects within the detectors. However, the advent of modern fast computing clusters has made large scale simulation of an instrument’s response now possible. By combining instrument data and results from detailed Monte-Carlo Mass-Model simulations using GEANT 4, it is possible to put constraints on the polarisation characteristics of the gamma-ray flux emitted by a source. Using the Compton scattered events in the SPI instrument on INTEGRAL, constraints have been put on the percentage polarisation in the prompt gamma-ray flux of GRB041219a to be 96±40% at 68% confidence and greater than 5% at 99.7% confidence. The method has also been extended to allow the summation of multiple data sets to obtain a measurement of the off-pulse polarisation of the Crab pulsar of 46% ± 10% at an angle of 123° ± 11°, showing a remarkable alignment to the rotational axis of the spinning Neutron star.
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Published date: 2007
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Local EPrints ID: 466583
URI: http://eprints.soton.ac.uk/id/eprint/466583
PURE UUID: 32bf426b-33c1-43b7-9e9a-657ed14fbdd6
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Date deposited: 05 Jul 2022 05:53
Last modified: 16 Mar 2024 20:47
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Author:
David John Clark
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