Collection of information about russian SNM tubes

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Lukas Springer
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Collection of information about russian SNM tubes

Post by Lukas Springer »

Some information was brought together in a trading post, this is that information condensed down before the thread in trading gets deleted.

As many of you are aware some russian SNM tubes are floating around and there seems to be much confusion on how to use them,
This problem is not made easyer by the fact that there are many different types of detectors under the same name.

SNM tubes can be:
-Boron 10 as cathode coating in corona tubes (SNM9-14)
-10BF3 as fill gas in proportional tubes (SNM3, 5, 8 & 20)
-Helium 3 corona (see link below)
-Helium 3 proportional (see link below)

It's hard to get datasheets for most of them, but a russian manufacturer is still supplying some of the He3 tubes, with datasheets:
http://consensus-group.ru/radiation-cou ... n-counters

I have only worked with my SNM-18-1 so far, which is a 4.6 bar 3He corona tube, if you have a different detector please post your results here :)

We all know the paper by Bob Higgins, which I would like to add to.

This is Higgins' circuit for driving 3He corona tubes:
Higgins.PNG
Which gives me the following trace for a neutron event:
DS1Z_QuickPrint5.png
DS1Z_QuickPrint5.png (36.29 KiB) Viewed 14571 times
This is the circuit described by Consensus-group in their SNM-18-1 Datasheet:
corona tube.PNG
Which gives me the following trace for a neutron event:
DS1Z_QuickPrint4.png
DS1Z_QuickPrint4.png (36.54 KiB) Viewed 14571 times
As you can see, using 16k to "terminate" the signal all of the high impedance corona noise is removed and all you get is a clean pulse, which can easily be amplified, needing almost no noise rejection.

The current through my tube is 8 µA with 100 MOhm and 14 µA with 47 MOhm (both at 2400V), allthough the output signal dosen't seem to change in amplitude with different currents, which might be explained by the very constant voltage across the tube.
I'd assume the same circuit works for 10B corona tubes aswell.

I can't say anything about my tubes sensitivity, but 4.6 Bar 3He are 4.6 Bar 3He.

If you have any further information about any of the SNM tubes feel free to add it here!

Lukas
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Re: Collection of information about russian SNM tubes

Post by Lukas Springer »

Next thursday I'm getting access to a decent neutron source, to test the detectors properly.
Right now I have 1 SNM-18-1 He3 and 2 SNM-11 B10 tubes.

I will try to measure their efficiency, gamma rejection, if they can be used in the proportional region, etc.

Is there anything you want to be tested?
Anything specific you want me to focus on?
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Re: Collection of information about russian SNM tubes

Post by Lukas Springer »

I finally got around collecting the data, here are my results:

My setup was:
Canberra 3106D HVPS
HP 5554A charge sensitive preamp (47M Bias Resistor)
Canberra 2031 SCA
NM 172 Ratemeter
Rigol DS1054z Oscilloscope

Amersham Buchler 3.7 GBq AmBe source, ~2.2E5 n/s

One SNM-18-1 4.6 Bar He3 Corona tube
Two SNM-11 10Boron coated Corona tubes
A cylindrical paraffin moderator, 6 cm of paraffin around the detector tube

Settings of the preamp were 300 mV/pC * 4 for the He3 tube and 30 mV/pC * 8 for the B10 tubes.
The SCA was set to a 1 to 4V Window.
Since I have two SNM-11 and they behaved somewhat differently I'll be talking about SNM-11(1) and SNM-11(2) from now on.
All tests on both SNM-11 were done at 1600V, the SNM-18-1 was tested at 2500V.

Currents were:
SNM-11(1): 18 µA
SNM-11(2): 19µA
SNM-18-1: 22µA

Neutron events were one to four volts out of the SNM-18-1 and one to two volts for both SNM-11, giving 0.8 to 3.3 pC in He3 and 4.2 to 8.3 pC in B10.
Corona noise was 300 mVpp in the SNM-18-1 and 900 mVpp in both SNM-11, making noise rejection somewhat harder in the B10 tubes.

With these values and SCA settings gamma rejection was very strong, as you can see in the videos below:

https://www.youtube.com/watch?v=y4AhhCfnhHU [SNM-18-1 without moderator]
https://www.youtube.com/watch?v=Aea0pQJH3s4 [SNM-18-1 with moderator]
https://www.youtube.com/watch?v=vuOvGY0QWSg [Gamma only dose rate of the neutron source]

I measured the absolute efficiency of my detectors by measuring count rate with the source 1 meter away from the detector, resulting in:
SNM-18-1: 60 cps
SNM-11(1): 6 cps
SNM-11(2): 4 cps

Giving me an absolute efficiency of 6.5%, 0.65% and 0.43%; as you can see the He3 detector is way more sensitive than both B10, which can be attributed to a higher active volume.

I also played around with the SNM-11 tubes connected to my ludlum model 3, and it is possible to use them at 1500V, if you put an external 100 Mohm with 100 pF in parallel in series to the tube.

https://www.youtube.com/watch?v=nwrPYnFZ0ps [Ludlum model 3 with SNM-11]
https://www.youtube.com/watch?v=7iItkYCuHlo [Ludlum model 3 with SNM-11 beta rejection, ~2 MBq Sr90]
https://www.youtube.com/watch?v=GL5I2hd6H7Y [Ludlum model 3 with SNM-11 gamma rejection, ~50 µSv/h pitchblend]

At ~2/3 of the corona ignition voltage all three tubes have a "proportional" region, but gamma rejection is extremly hard, so I did not persue this any further.

The geiger counter in those videos (Graetz X50zs) is energy compensated and goes from "ticking" to a solid beep above 25 µSv/h.

As you can see those russian corona tubes are very good neutron detectors and can definitely be used to detect fusion.
I hope they'll get more love and appreciation in the future!

If you have any further questions I'd be happy to help!

Lukas
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Re: Collection of information about russian SNM tubes

Post by Joe Gayo »

Can you try running the CHM-11 just below the corona starting voltage (ie 670V)?
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Re: Collection of information about russian SNM tubes

Post by Lukas Springer »

From ~2/3 of the corona ignition voltage to the ignition voltage it is in that "prop mode" region, being very responsive to gamma.
What do you want to achive with running it below its nominal voltage?
Maybe I can test for that.
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Re: Collection of information about russian SNM tubes

Post by Joe Gayo »

The SNR improved dramatically, so gammas can be discriminated
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Re: Collection of information about russian SNM tubes

Post by Lukas Springer »

There is no corona noise, that is true, but gamma peaks get huge.
With some corona current gamma rejection becomes really easy, since all gamma events are drowned out in the noise and only neutron events get above it. Setting your disc to ~1.5 times the voltage of your noise pretty much garantees you to discriminate against all non-neutron events.
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Richard Hull
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Re: Collection of information about russian SNM tubes

Post by Richard Hull »

The take-away, from my view point, over all these years of hoopla, is that the Russian neutron tubes are tricky to use and adjust if you do not have co-existing a decent neutron source to compare against a decent Gamma source. Neutron sources are very tough to come by, while decent gamma sources very easy to obtain. Radium is easy to get in old war bird instrumentation found at hamfests. Many fleamarkets have old large wesclox "Big Ben" alarm clocks. 10 uCi Cs137 sources in the U.S. can be ordered through the mail. Such items blast out rather significant amounts of easily detectable gammas up to over 1mev with most in the 200-600kev range. For really hot gammas a Thorium chemical compound is what you want as thorium spits out a copious quantity of gamma over 2 mev.

To really tune and see what is counted and what is truly rejected, a decent video needs to be made with a nice setup just like Lucas and others here have at their disposal. A really hot gamma source needs to be placed next to the tube in question, (no moderator). Using an oscilloscope, the bias needs to be adjusted to show that as the bias is raised the gammas at various levels of increasing bias start to, effectively, disappear. At this point in the effort, insert the tube into a moderator and place the neutron source next to the gamma source, still showing the oscilloscope. Ideally, the neutron source should be suddenly obvious, maybe at a low level, but plainly there. If not, you haven't shown anything related to neutron counting or gamma rejection.

If it turns out there is a real hyper-narrow bias range where gamma rejection is acceptable and neutron counting will rise out of the noise using windowing techniques, then you have something that might be worth using. While not a great system due to the criticality of adjustment, you are assured that as long as all things remain equal, the tube is good and counting neutrons and neutrons only.

Naturally, there is a local and cosmic background, but that is normal. A good system should not see more than 8 to 15cpm of real background.

I am sorry I do not have a Russian neutron tube to monkey with.

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
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Re: Collection of information about russian SNM tubes

Post by Lukas Springer »

I'm sorry, maybe I'm bad at explaining, but I wanted to make the point that people don't have to be "scared" by those russian detectors, but that they're instead pretty easy to use once one got the hang of it. They reject the 59 keV of Am-241, tested with a source giving off > 3mSv/h at point blank, and the U-238 / Ra226 spectrum, tested with a piece of pitchblend giving off >50 µSv/h, perfectly well.

Instead of tuning an operating point they're quite comfortable at their rated voltage with a 47 Mohm bias resistor, gamma rejection is done by rejecting everything below ~1.5x the corona noise peak to peak voltage.

I have compared the counting rates with and without neutrons / gamma / moderator, the setup described above is the result of that

My He3 tube gives ~12 cpm background, the SNM-11 <5 cpm.

Lukas
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Steven Sesselmann
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Re: Collection of information about russian SNM tubes

Post by Steven Sesselmann »

Hi Guys,

Just a reminder that David Housley and myself developed this little board for the Russian Corona counters, specifically the SNM-12 (CHM-12) and similar tubes. It's a schmidt trigger circuit and turns the noisy signal into a nice flat baseline with strong pulses.

It can operate on a 9V battery for several days, but requires an external HV source.

GS-PREAMP
GS-PREAMP


https://www.gammaspectacular.com/blue/g ... eutron-pcb

Steven
http://www.gammaspectacular.com - Gamma Spectrometry Systems
https://www.researchgate.net/profile/Steven_Sesselmann - Various papers and patents on RG
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Re: Collection of information about russian SNM tubes

Post by Lukas Springer »

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?

Lukas
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Steven Sesselmann
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Re: Collection of information about russian SNM tubes

Post by Steven Sesselmann »

Lukas,

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
http://www.gammaspectacular.com - Gamma Spectrometry Systems
https://www.researchgate.net/profile/Steven_Sesselmann - Various papers and patents on RG
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Re: Collection of information about russian SNM tubes

Post by Richard Hull »

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 fusor.net 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 "knack" 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
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
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Re: Collection of information about russian SNM tubes

Post by Steven Sesselmann »

Lukas Springer wrote: Thu Feb 28, 2019 4:58 am
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?

Lukas
Lucas,

I have an update on the efficiency numbers for the SNM-12. I built a GS-NEUTRON for a client and had it calibrated by ANSTO here in Australia and the average efficiency over a radius of 0.4 to 2.2 meters came in at an nvth of ~ 0.395 this is about 250% more efficient that I initially calculated based on measurements at the University of Sydney.

Send me a PM if you want a copy of the calibration certificate

Steven
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Re: Collection of information about russian SNM tubes

Post by Michael Kaufmann »

Lukas Springer wrote: Tue Oct 16, 2018 4:32 am If you have any further information about any of the SNM tubes feel free to add it here!

about sensitivity of a soviet CHM tubes:


Image


so for CHM-18 it's like 50 counts per n*cm^2*sec if i understand correctly?
I can't say anything about my tubes sensitivity, but 4.6 Bar 3He are 4.6 Bar 3He.
are your tube brand new, or more like 30 years old? if the latter - don't you think you would be lucky to have as much as 2 bar in there probably? : )

i can't post images yet, but i have more data - like gamma rejection levels for example.
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Re: Collection of information about russian SNM tubes

Post by Richard Hull »

I agree that what info is to be found and shared regarding these corona tubes, is best placed as a reply to this thread. Sadly, all the circuit diagrams and other submitted images appears to be lost forever during our ill fated move to Go Daddy a couple of years ago.

Richard Hull
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Fusion is the energy of the future....and it always will be
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Re: Collection of information about russian SNM tubes

Post by John Futter »

Richard
Why do you answer these trolls who cannot abide by the rules??
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Richard Hull
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Re: Collection of information about russian SNM tubes

Post by Richard Hull »

If information is exchanged, data provided and on point, with no attempt to foul the thread in a negative way or to advertise a product, I will answer. I did not look at the fact this was a first positing with no real name. It is indeed sad that so many posts here for the first time are submitted by those not following the simple sign up rules. You keep poking them for this failure and I'll continue to lock out the trash. I tend to not focus on the names or number of postings if the submission is sound.

I will again note to the poster, if still here, that we do not use block quotes as he did in our replies in a thread!

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
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
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Michael Kaufmann
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Re: Collection of information about russian SNM tubes

Post by Michael Kaufmann »

hi Richard.
I fixed the problem with the name, tho not with the first post (will do it soon). i came here from the pupman tesla coil mailing list - there were not so many restrictions : )
what are "block quotes" - aren't my two quotes the same as Steven Sesselmann's on this page?

p.s.
how much posts i need to be able attach pictures from datasheets for example?
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Re: Collection of information about russian SNM tubes

Post by Dennis P Brown »

First off, our rules are so simple and limited that it is really amazing people consider them intrusive or even an issue (from day one, before it was a rule, I only used my full name); however, do understand we are a formal site that strives for exchange of scientific and technical information. As such, being professional is not optional unlike so many other sites. That said, we all error from time to time - I certainly have/do. But for a first post you, unfortunately, hit the trifecta. No big deal. You've fixed the most important issues and in the future, just avoid block quotes. I.e. creating large boxes containing previous statements by other people. This eats up storage for saved posts/threads.

Second and most importantly, we try to show by our posts that we are professional and treat this site like the useful forum it has become. Glad you have decide to join and don't worry too much about what occurred previously - just continue and do help to make this a great site for fusor work.
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Richard Hull
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Re: Collection of information about russian SNM tubes

Post by Richard Hull »

In response to your question....Are not my quotes those from Steven Sesselmann's on this same page?....In response... Yes, they are his exact words and they are absolutely unnecessary. We have already read those words of his above and need not be reminded of them. We are smart readers and need not be reminded of the exact words in any preceding posts. Block quotes are any verbiage in your current post that is in shaded gray "block" which quotes from another post within any given entire thread. We do not like block quotes in gray in responses. Your responses in your posts should be all your own words.

The above request is commonly noted to new folks here. Avoid block quotes from previous posts in a thread.

To my knowledge there is no restrictions on posting images of any sort on new people. To the contrary it is highly recommended. A picture is worth a thousand words. Your table of official, published efficiencies was most welcomed.

Note: Block quotes are OK if you are referring to some quote made way back in a thread of some months or years ago. Do not use them in response to a recent running thread

Richard Hull
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Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
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Re: Collection of information about russian SNM tubes

Post by Michael Kaufmann »

shall we continue? : )

bias voltage selection:

подбор режима питания.png

absolute maximum sensitivity (counts*cm^2/n) of counters to neutrons of various spectra:

чувствительность.png
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Re: Collection of information about russian SNM tubes

Post by Dennis P Brown »

Nice graphs but any chance we can get some translation into English on the key points (graph parameters.) Maybe a bit on the context of the articles - I see it is a voltage vs. some type of response for each detector type.
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Re: Collection of information about russian SNM tubes

Post by Richard Hull »

The RS-P4 and P7 references in the graphs and table are comparison to the famous industry standard Reuter and Stokes P4 (4ATM 3He) and P7 (7ATM 3He) proportional detector tubes to the Russian tubes. I have since 2004 only used the RS-P4, 21-inch long tube in my neutron detection system.

Richard Hull
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Re: Collection of information about russian SNM tubes

Post by Joe Gayo »

@Michael

Can we get the entire document? I would like to translate.

Thanks
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