Collection of information about russian SNM tubes

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.
Lukas Springer
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Re: Collection of information about russian SNM tubes

Post by Lukas Springer » Thu Feb 28, 2019 9:58 am

Which just goes to show how easy to use those tubes are :)

No window comparator needed, no fine tuning, just a comparator with some hysteresis and done!

I've got a question for you, steven:
You spec your GS-NEUTRON-150 as 15% efficiency, is that with the moderator in a fast neutron field or just a spec for the tube and thermal neutrons?


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Steven Sesselmann
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Re: Collection of information about russian SNM tubes

Post by Steven Sesselmann » Thu Feb 28, 2019 10:59 pm


As you know the specs are all in Russian and if I recall correctly only lists background or self count.

My estimate for the efficiency of the SNM-12 tube is based on some tests I did at the University of Sydney with an AmBe neutron source said to emit around 2x10^6. Tests were done with a 90 mm cylindrical HDPE moderator at various distances and based on the source activity we worked out the efficiency of the tube to be around 0.15 nvth.

This also agrees roughly with the background counts we get from these tubes.
Which just goes to show how easy to use those tubes are :)
I would go as far as calling these tubes "easy to work with". If you don't have a decent oscilloscope you probably think they are damaged or not working. Signal is noisy and background counts are far and few between... blink and you miss it! But if you know what you are looking for and have a fast scope with a trigger set correctly you will catch a neutron every 10 -15 minutes.

Make sure to run these tubes with a high load resistance 50 Mohm or more.

Steven - Gamma Spectrometry Systems - Various papers and patents on RG

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Richard Hull
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Re: Collection of information about russian SNM tubes

Post by Richard Hull » Fri Mar 01, 2019 12:07 am

The key expression is "once you get the hang of it" or "if you have a fast oscilloscope". All good, honest and wise observations. I continue to applaud all those here who are willing to help in the effort based around what I term, "The Russian neutron tube dilemma". That is an effort to make these rather inexpensive and available tubes do "good service" as advertised in their name...."Neutron detector". Any good nuclear metrologist realizes that neutron measurement is tricky, at best, and deception can be the order of the day without plus-ultra instrumentation and a person who knows how to use it in the environment the measurement is taken.

A keen observer here at will come to understand that there are but a tiny few here who are willing to learn to get the "hang" of anything! There are even fewer with a fast o'scope. Having both a person so equipped and willing to struggle to get the "hang" and the fabulous rewards associated with the struggle, be it difficult or relatively easy, is a great rarity here. Yes, there will always be a few of us. We will teach and hopefully we will help to get others used to "getting the hang" of how to bring hardware to the point of doing what is claimed or expected of it.

For many here, hooking up a 555 timer is beyond the scope of their background. Pumping variable high voltages into a biased nuclear detector, be it proportional, corona or gas amplification based, is a mystery and, often, a bridge too far for the vast majority here. Recognizing that others are knowledge and "kit" limited is often very tough and the word "easy", used by the most advanced here, can be all too readily applied.

My old saw of "Nuclear fusion is easy to do" is very much correct, but misleading. Compared to any other fusion process on the planet, it is abysmally easy to do if you look at and compare costs and complexity to achieve easily detectable nuclear fusion producing millions of fusions per second.

Still, all those of us who can "do", and are equipped to "do", create and work on evolving, useful, posts like this one. For those capable few, the Russian tubes are an option, yet the rules for claiming fusion remain moderately biased against them. Thus, we are requiring extra evidence that a Russian tube based counter is really working as a neutron detector. Unfortunately, it is all too easy to have it function as a GM counter or, more likely, a noise detector, if you don't have the "nack" or have gotten the "hang" of how to bias and discriminate the other radiations or noise out of the picture.

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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