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Determination of the optimum-size californium-252 neutron source for borehole capture gamma-ray analysis

Nuclear Instruments and Methods

By:
, , and
DOI: 10.1016/S0029-554X(79)92890-8

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Abstract

The fast- and thermal-neutron fluence rates from a 3.7 ??g 252Cf neutron source in a simulated borehole have been measured as a function of the source-to-detector distance using air, water, coal, iron ore-concrete mix, and dry sand as borehole media. Gamma-ray intensity measurements were made for specific spectral lines at low and high energies for the same range of source-to-detector distances in the iron ore-concrete mix and in coal. Integral gamma-ray counts across the entire spectrum were also made at each source-to-detector distance. From these data, the specific neutron-damage rate, and the critical count-rate criteria, we show that in an iron ore-concrete mix (low hydrogen concentration), 252Cf neutron sources of 2-40 ??g are suitable. The source size required for optimum gamma-ray sensitivity depends on the energy of the gamma ray being measured. In a hydrogeneous medium such as coal, similar measurements were made. The results show that sources from 2 to 20 ??g are suitable to obtain the highest gamma-ray sensitivity, again depending on the energy of the gamma ray being measured. In a hydrogeneous medium, significant improvement in sensitivity can be achieved by using faster electronics; in iron ore, it cannot. ?? 1979 North-Holland Publishing Co.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Determination of the optimum-size californium-252 neutron source for borehole capture gamma-ray analysis
Series title:
Nuclear Instruments and Methods
DOI:
10.1016/S0029-554X(79)92890-8
Volume
158
Issue:
C
Year Published:
1979
Language:
English
Publisher:
Elsevier
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Nuclear Instruments and Methods
First page:
293
Last page:
302
Number of Pages:
10