The purpose of this research is to design and optimize the performance of a unique,
inexpensive 6Li neutron-capture pulse-mode ion chamber (LiPMIC) for neutron
detection that overcomes the fill-gas contamination stemming from outgas of detector
components. This research also provides a demonstration of performance of LiPMICs.
Simulations performed with GARFIELD, a drift-chamber simulation package for ion
transport in an electrostatic field, have shown that argon-methane mixtures of fill-gas
allow maintenance of electron drift velocity through a surprisingly wide range of fill-gas
content.
During the design stage of LiPMIC development, the thicknesses of lithium
metallization layer, the neutron energy conversion site of the detector, and the thickness
of neutron moderator, the high-density polyethylene body, are optimized through
analytical and MCNPX calculations. Also, a methodology of obtaining the suitable
combination of electric field strength, electron drift velocity, and fill-gas mixtures has been tested and simulated using argon-methane gas mixtures. The LiPMIC is shown to
have comparable efficiency to 3He proportional counters at a fraction of cost. Six-month
long baseline measurements of overall detector performance shows there is a 3%
reduction in total counts for 252Cf sources, which provides a good indicator for the
longevity of the detector.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/ETD-TAMU-3022 |
| Date | 15 May 2009 |
| Creators | Chung, Kiwhan |
| Contributors | Braby, Les A. |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Dissertation, text |
| Format | electronic, application/pdf, born digital |
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