High count rates are desired because they produce small counting uncertainties. Lab C offers two types of count enhancing for moderated sensors:
(1) A new Li-core thermal neutron detector has 3.5 times the count rate of the COSMOS standard He-based sensor (both equipped with the standard 1-inch moderator).
(2) A new proprietary count enhancement technique [Patented technology] yields up to two times higher moderated neutron count rates from the same thermal neutron detector. For Li-core detector this factor is 1.3; for He-core detector it is 2; and for BF3 it is 1.6.
SurfaSens [Patented technology] measures neutrons at the scale that is commensurate with the dimension of the instrument’s bottom plate. This sensor enables high-resolution (1 m to 10 m) mapping of cosmogenic neutrons, soil moisture, and other hydrogenous materials at or near the land surface. It is uniquely useful in measuring moisture of soils with stones or rock outcrops. It can be used to calibrate the standard, wide-area COSMOS sensor.
The sensor is also suitable for finding hydrogenous materials in soil or at its surface, measuring water content of bulk materials such as grain or ore, solid materials such as concrete, construction materials such as wood, agricultural materials such as crops or hay, etc.
A new moderated sensor with Li-core thermal neutron detector (left side in the photo) has been constructed and is being tested against the standard He-core sensor (right side) at the Santa Rita Mesquite COSMOS site.
The side-by-side measurements conducted between December 2017 and March 2018 revealed that:
(1) The count rate of the new sensor is more than three times higher than that of the He-based system. Therefore, the uncertainty due to counting statistics is reduced by approximately a factor of 1.7. In the figure below it is manifested by smaller noise in the Li-core count data (top figure) and by lower coefficient of variation (bottom figure).
(2) The dynamic range of the Li-core sensor is almost identical to the standard He-core COSMOS sensor.
Application. The new Li-core moderated sensor is an excellent replacement for the He systems. The price of the Li-core sensor is comparable to that of the standard He-core sensor. Combined with other count-enhancing techniques, it yields an estimated nine-fold increase of the count rate, as compared with the standard COSMOS He-core sensor.
