Influence of access hole parameters on neutron moisture probe readings
Computing soil moisture content with a neutron probe requires use of a calibration curve that considers the thermal neutron capture cross section of the hole liner as well as the hole diameter. The influence of steel, polyvinyl chloride, and aluminum casings that fit 0.051 to 0.102-hole diameters was determined by comparison with neutron probe readings in uncased holes of corresponding diameters. Eccentricity of probe location was considered a potentially significant variable. The relationship between hole diameter and count rate also was investigated. The experiment was run in disturbed Bandelier tuff with an average dry density of 1.2 g . cm/sup -3/ and moisture content of 1.3 to 35.5% by volume. The casing material and hole diameter influenced the probe readings significantly, whereas eccentric location of the probe did not. Regression analyses showed an almost perfect inverse linear correlation between hole diameter and count rate.
- Research Organization:
- Los Alamos Scientific Lab., N.Mex. (USA)
- DOE Contract Number:
- W-7405-ENG-36
- OSTI ID:
- 6936744
- Report Number(s):
- LA-7241-MS
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
BARYONS
CALIBRATION
CORRECTIONS
COUNTING RATES
ELEMENTARY PARTICLES
ERRORS
FERMIONS
HADRONS
MEASURING INSTRUMENTS
MOISTURE
MOISTURE GAGES
NEUTRONS
NUCLEONS
PIPES
RADIOMETRIC GAGES
SIZE
SOILS