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Probe background, technology, calibration, MCNP. Darin Desilets Hydroinnova. The instrument: CRS-1000. Connection to Iridium or cell phone. Pulse module. Data logger. 80 cm. Moderated tube (primary sensor). Bare tube (secondary sensor). Charge controller and 30 Ah battery.
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Probe background, technology, calibration, MCNP Darin Desilets Hydroinnova
The instrument: CRS-1000 Connection to Iridium or cell phone Pulse module Data logger 80 cm Moderated tube (primary sensor) Bare tube (secondary sensor) Charge controller and 30 Ah battery Darin Desilets
The instrument: CRS-1000/B Connection to Iridium or cell phone antenna Data logger 130 cm Bare or moderated tube inside Pulse module Charge controller and 30 Ah battery Darin Desilets
Comparison CRS1000 CRS1000/B Darin Desilets
Same sensitivity? major rain event Darin Desilets
Neutron scattering theory Darin Desilets
Neutron scattering theory E > 10 eV Moderated tube E < 0.1 eV Bare tube Darin Desilets
Energy sensitivity for moderated and bare detectors Darin Desilets
Why use bare counter? • Built-in pressure/solar activity correction • Provides long-term check on stability • Separate snow from soil moisture (?) • Basic research • Canopy snow and water • Biomass • Added issues: • Presence of local absorbers (no universal cal!) • Some very local responses • Greater depth penetration? Darin Desilets
Bare counter enhancements? Bare Moderated Kerplop! Darin Desilets
Improved uncertainty for soil moisture determinations s2total=s2stat + s2syst Limiting case 1: bare tube has same sensitivity to soil moisture as moderated tube. Add counting rates, reduce sstat by ~40% Limiting case 2: bare tube has low sensitivity to soil moisture Use bare to reduce ssyst Darin Desilets
Modeling neutrons with MCNP Monte Carlo Neutral-Particle The original Monte Carlo application Remains the “gold standard” for neutron transport Flexible source specification, geometries, tallies Overkill? Maybe so Darin Desilets
Summary Current configuration is optimized for COSMOS—but other configurations are possible. Bare counter: not critical but has certain advantages when used with mod tube. MCNP code: an essential tool for basic research with the cosmic-ray probe. Darin Desilets