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Title: Dynamic flat-fielding of BATSE data and the BATSE all sky survey
Author: Westmore, Matthew Joseph
ISNI:       0000 0001 3566 2379
Awarding Body: University of Southampton
Current Institution: University of Southampton
Date of Award: 2002
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This thesis describes developments made by Matthew Westmore that will further the Compton Gamma Ray Observatory's (CGRO) contribution to high energy astrophysics with the production of the first all sky survey in the 25-1000 keV band. The BATSE instrument served as CGRO's all sky survey viewing the entire sky continuously for the 9 year CGRO mission. Earth occultation techniques have been applied to the BATSE database since launch to study transient and steady sources. The standard occultation techniques suffer from two main limitations; the background problem and the interference problem. The interaction of particles from the cosmic diffuse background, atmospheric albedo emission, and cosmic ray protons provide the dominant sources of noise. The response of the BATSE detectors to these sources is further complicated by orbital modulation. These slowly varying components to the BATSE background counting rates introduce systemic uncertainties and limit the sensitivity. Since the BATSE detectors are uncollimated and the Earth's limb is extended, the Earth occulation techniques suffer from the effects of interfering sources. This again introduces systemic uncertainties and limits the sensitivity. This thesis details work completed to address these two limitations so that the BATSE database may be fully exploited. The slowly varying background noise components from the detector counting rates have been removed wit the use of particle physics-based Monte-Carlo simulations. Semi-empirical fitting to the data to determine the background model parameters is not adequate. A fully physical computational model of the various sources of background has been developed over the last decade in Southampton and provides the desired level of accuracy. The author has been involved in adapting this technique to remove the background levels from the raw detector counting rates before carrying out further analysis. This process is known as dynamic flat-fielding.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: High energy astrophysics