Brearley, Ian (1977). The calibration of recoil proton proportional spectrometers and the measurement of neutron slowing down spectra in a lithium fluoride assembly. University of Birmingham. Ph.D.
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Brearley1977PhD.pdf
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Abstract
Growing concern about the world's future energy resources has led to an interest in neutronic behaviour in proposed fusion reactor materials. In this case the neutron slowing down spectra in lithium fluoride are examined at various distances from the neutron source. From the several methods available for measuring neutron spectra the recoil proton proportional counter was chosen.
The calibration of these counters is then discussed; in particular, the common assumption that the average energy loss per ionisation (W) is constant over the counter's energy range is shown to be invalid. In the calibration measurements it was found that the behaviour of W with energy was markedly different for the two hydrogen fillings. This difference was attributed to the influence of electronegative impurities in the gas in the counter. Further, a model assuming that the specific energy loss per ionisation (ω) was constant was found to be valid over the counter's energy ranges.
The response function shape, although sensitive to scattered neutrons, was found to be determined by the counter's dimensions, gas filling and known electric field distortion.
Finally, the calibrated counters were used to measure neutron slowing down spectra in a spherical lithium fluoride assembly over an energy range of 60 KeV to 2.5 MeV. The spectra were compared with calculated spectra and good agreement in shape was found although discrepancies existed in their absolute values. These discrepancies were attributed to a secondary neutron source and its contribution was assessed using a continuous flow water bath to measure the total neutron yield.
| Type of Work: | Thesis (Doctorates > Ph.D.) | ||||||
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| Award Type: | Doctorates > Ph.D. | ||||||
| Supervisor(s): |
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| Licence: | All rights reserved | ||||||
| College/Faculty: | Faculties (to 1997) > Faculty of Science | ||||||
| School or Department: | Department of Physics | ||||||
| Funders: | None/not applicable | ||||||
| Subjects: | Q Science > QC Physics | ||||||
| URI: | http://etheses.bham.ac.uk/id/eprint/12699 |
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