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Title: An investigation into a fast response total-radiation detector for high temperature physics
Author: Cooper, John
Awarding Body: Imperial College London
Current Institution: Imperial College London
Date of Award: 1962
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The object of this thesis is to investigate the possibility of a total radiation detector for use in High Temperature Physics Research. The criterion taken being a detector which would handle a radiation pulse of length 100p sec with a time constant of better than lp sec and accuracy of about 1%. (Compared with 50p sec which is the best at present available), Total radiation measurements require a uniform spectral response as obtained with a black—body absorption i,e. with a surface black, The conduction equation for a radiation flux incident on a black on a material body is solved, by the Method of Laplace transforms, to give the temperature distribution in the body in terms of the incident flux. Improvement of standard resistive bolometers in terms of the above criterion is considered. A pyroelectric type of detector, in which a voltage output is obtained due to change on heating of spontaneous polarisation in a ferroelectric, is examined theoretically in great detail. The theoretical examination includes different types of electrode mounting on the unit (generally single crystal or ceramic barium titanate), the effect of piezoelectric output due to thermal expansion exciting resonances (a sort of thermo—mechanical coupling), the tertiary piezoelectric effect, and various possible and effects. Experimental work on the pyroelectric detector using the linear discharge equipment at Imperial College indicates that theory is closely obeyed and the actual tine constant is limited by the frequency of mechanical resonances (giving a piezoelectric output). The units manufactured have a tine constant of about 5p sec and a highly reproducible output, but these can easily be developed to give 1p secs tine constant and are capable of handling the high energy fluxes obtained in thermonuclear research. An appendix has been added showing that the pyroelectric detector can also be used as a very sensitive detector when used with a long time constant.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available