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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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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Trent Carter
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Re: Calibrating a Neutron Detector With Background Neutrons

Post by Trent Carter » Thu Sep 05, 2019 1:53 am

Thank you for sharing this. I have spent the better part of 3 years researching, scouring, and purchasing neutron detection hardware.

A. Somehow I had missed the CT007-T neutron detector, likely because it has not yet been released. They dont disclose the technology. My guess is LiI(Eu) or CLYC.
B. I liked the scientific process in the video with Background No Mod / BGND+Mod / BGND+MoreMod / BGND+Boron. I think I might add a Boron test to my Neutron calibrations in early 2020.
C. I have always wondered why one could not calibrate a baseline with background Neutrons.
D. I had not considered background calibration using thermalized Vs fast and boron no-boron.

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