and Other Applications Hydrology Neutron Monitor Community WorkshopHonolulu Hawaii October 2425 2015 Physicist National Urban Security Technology Laboratory Science and Technology Directorate ID: 421971
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Use of Cosmic-Ray Neutron Data in Nuclear Threat Detection and Other Applications: Hydrology +
Neutron Monitor Community Workshop—Honolulu, Hawaii
October 24-25, 2015
PhysicistNational Urban Security Technology Laboratory Science and Technology Directorate
Paul GoldhagenSlide2
Measure soil water, snow, biomass using cosmogenic neutronsPreviously elusive scale, tens of hectares, 10
– 60 cm deep Same principal as Am-Be soil moisture gauges: water moderates / thermalizes evaporation (MeV) neutrons
Use moderated (and bare) neutron detectors to measure rates of 1 – 1000 eV slowing-down neutrons (and thermals)
Over 200 probes in useCOSMOS network in U.S. (
NSF); networks in other countries
Thermal-neutron rate depends on soil composition
Normalize using neutron monitor rate; best if nearby (U.S.)
HydrologyZreda, Desilets, et al., Univ. of Arizona, Sandia Natl. Lab.
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Cosmic-ray neutron spectrum
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Thermal
High energy
Slowing-down region ~1/E
EvaporationSlide4
Cosmic-ray neutron surface moisture probe
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M. Zreda
, Third COSMOS
workshop, 2012Slide5
What is sensed
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M. Zreda
, Third COSMOS
workshop, 2012Slide6
Measure soil water, snow, biomass using cosmogenic neutronsPreviously elusive scale, tens of hectares, 10
– 60 cm deep Same principal as Am-Be soil moisture gauges: water moderates / thermalizes evaporation (MeV) neutrons
Use moderated (and bare) neutron detectors to measure rates of 1 – 1000 eV slowing-down neutrons (and thermals)
Over 200 probes in useCOSMOS network in U.S. (NSF); networks in other countries
Thermal-neutron rate depends on soil compositionNormalize using neutron monitor rate; best if nearby (U.S.)
Hydrology
Zreda, Desilets, et al., Univ. of Arizona, Sandia Natl. Lab.
6Slide7
Cosmic-ray probe locations (2012)
7
M. Zreda
, Third COSMOS
workshop, 2012
2012: 123 probes 2015: >200 probesSlide8
Measure soil water, snow, biomass using cosmogenic neutronsPreviously elusive scale, tens of hectares, 10
– 60 cm deep Same principal as Am-Be soil moisture gauges: water moderates / thermalizes evaporation (MeV) neutrons
Use moderated (and bare) neutron detectors to measure rates of 1 – 1000 eV slowing-down neutrons (and thermals)
Over 200 probes in useCOSMOS network in U.S. (NSF); networks in other countriesThermal-neutron rate depends on soil composition
Normalize using neutron monitor rate; best if nearby (U.S.)
Hydrology
Zreda, Desilets, et al., Univ. of Arizona, Sandia Natl. Lab.
8Slide9
Another group of other applications ofcosmic-ray neutron data
9Slide10
Cosmic-ray neutrons create cosmogenic radionuclides in the air and ground
Atmospheric tracers (7Be)Geological dating (
10Be,14C, 36Cl, …)Background for neutron activation measurements
Source terms require knowledge of cosmic-ray neutron spectrum and intensity For shorter half-life nuclides, intensity requires neutron monitor data
DS2002 resolution of Hiroshima neutron dosimetry discrepancyMeasurements of neutron activation nuclides in Hiroshima samples (36
Cl,
60Co, 63Ni, 152Eu) seemed high at large distances. Actually caused by cosmic-ray neutron background.
Production of cosmogenic radionuclides
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