Inquiry on a primitive neutron detector.

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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David Vermilion
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Inquiry on a primitive neutron detector.

Post by David Vermilion » Wed Sep 18, 2019 4:56 pm

I got to thinking about how expensive and complicated neutron detection is. $250 at least for a BF3 tube or 1-2K American-dollhairs for a He3 tube or complicated electronics for a PV tube.

I thought that there's no way they had all this complicated gadgetry way back in the 1930s.

According to the wiki article on the discovery of the neutron (https://en.wikipedia.org/wiki/Discovery_of_the_neutron)

One of the first apparatus used was a polonium-beryllium source in a vacuum chamber. They separated the source from a cloud chamber by a large amount of paraffin wax. They were indirectly detecting the neutrons by thier effect on the large amount of hydrogen in the wax. Collisions between the protons and neutrons caused protons of high energy (5Mev) to be scattered.

Why not build a cloud chamber and shield it with steel or lead for x rays and gamma rays, leave a small opening for the protons to get through and cover it with paraffin wax. To ensure it is protons use a magnet to determin the partical's charge and make sure to keep away any stray alpha sources. Place it near the fusor and when you turn it on and tune it to the correct mode you should see a few tracks of protons.
This is just a half baked idea I'm tossing around. I don't really want to spend a lot of money on a BF3 tube that will expire in 6 months.

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Richard Hull
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Re: Inquiry on a primitive neutron detector.

Post by Richard Hull » Wed Sep 18, 2019 5:21 pm

Your idea is nice but highly impractical as it could not be effectively calibrated. Like we always say, try it and be the first to do it.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
Retired now...Doing only what I want and not what I should...every day is a saturday.

David Vermilion
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Joined: Mon Sep 16, 2019 4:07 am
Real name: David Vermilion

Re: Inquiry on a primitive neutron detector.

Post by David Vermilion » Thu Sep 19, 2019 3:40 am

Why would you want to calibrate it? You mean to give a definite answer to a certain number of neutrons/sec?

You could check its effectiveness against a am-be source. Which gives off a certain number of neutrons. Then just eyeball it.

This idea isn't meant to give hard or fast mesurments. Its more primitive than that. Think more like a mechanic pulling the spark plug of a car and turning the engine over to see if it sparks. Its primitive and cheap but it gives A result. Yes or no. (Unless you guys running the forum want a better result than that, which is fine your forum your rules.)

I'd imagine that if you wanted a very general CPM you'd put a thick steel/lead plate between the paraffin and the fusor and replace the cloud chamber with a Geiger counter pancake probe that has tons of lead or steel around it to block out all the background jitter. Like the setup you'd use for a gamma ray spectrometer. Even then you would have to use a normal Geiger counter tube to make sure you weren't picking up gammas, X rays or betas by mistake.

Thank you for you feedback I REALLY appreciate it!

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Richard Hull
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Re: Inquiry on a primitive neutron detector.

Post by Richard Hull » Thu Sep 19, 2019 5:02 am

Like I say...make a fusor do as you say and report back to us. The proof is always in the pudding. I think Jon Rosenstiel did this many years back; it worked. Just do it.

Sadly, Jon's fabulous images are now missing from his original post 16 years ago.

viewtopic.php?f=18&t=7748

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
Retired now...Doing only what I want and not what I should...every day is a saturday.

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