Calibrating a Neutron Detector With Background Neutrons

This area is for discussions involving any fusion related radiation metrology issues. Neutrons are the key signature of fusion, but other radiations are of interest to the amateur fusioneer as well.
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Kai Kaletsch
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Joined: Sat Oct 27, 2018 3:54 pm
Real name: Kai Kaletsch

Calibrating a Neutron Detector With Background Neutrons

Post by Kai Kaletsch » Sun Jan 27, 2019 9:01 pm

The thermal neutron fluence rate at the earth's surface is well known and we should be able to use that as a way to get an approximate calibration for neutron detectors. This video proposes a method: https://www.youtube.com/watch?v=OahvY0g ... e=youtu.be

The thermal neutron fluence at the reference location is supposed to be ~ 4 n/cm2/hr ( https://ieeexplore.ieee.org/document/1263842 ). At Saskatoon’s latitude and altitude, the n flux is 1.6 times reference ( http://www.seutest.com/cgi-bin/FluxCalculator.cgi ), or around 6.4 n/cm2/hr.

Borax absorbs thermal neutrons. So, by comparing the count rate of a detector surrounded by borax to the same detector bare, we can determine how much of the bare count rate is due to background thermal neutrons. Cadmium would be a better neutron absorber than borax but it isn't as readily available.

We found that our detector has a sensitivity of ~ 8.4 cps/nv.

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