Inquiry response from LND - 3He tube

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Re: Inquiry response from LND - 3He tube

Post by Richard Hull » Tue May 10, 2011 3:10 pm

Nice update on the update. I was wondering how a controlled gas could be obtained by LND for quotes on new 3He tubes..... As always, it is now just a matter of money.

Like all commodities, if the price goes high enough, sources once considered far too expensive to tap are finally mined for the goodie needed as others find boron lined work-arounds.

Good ole capitalism. All you need is money and, "you bet......we got it for yah"

As Bob Hope once said at his 1974 "Christmas Show", once the famous 1973-74 gas crisis had abated........."Well, the gas lines are gone and the crisis is a distant memory now.....It seems like there was only a shortage of cheap gas". He got a long, standing applause that interrupted his monologue and as the crowd re-seated themselves, he said, in his usual dry wit,......"Remind me to give that writer a pay raise."

Richard Hull
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Fusion is the energy of the future....and it always will be
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Re: Inquiry response from LND - 3He tube

Post by Frank Sanns » Tue May 10, 2011 5:03 pm

There are other technologies out there and I do not see the fuss about the He3. In some ways it is just like BF3 in that it is a commonly found item that is easy to make work with an SCA or a NIM bin. Even some of my portable neutron detectors use Li6 for example or other low voltage technology. Sure a big He3 gets you bragging rights but if you are looking for neutrons, there are other means.

Frank Sanns

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Richard Hull
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Re: Inquiry response from LND - 3He tube

Post by Richard Hull » Wed May 11, 2011 2:07 pm

As noted here in this forum before, the 3He is not about bragging rights, it is just the most sensitive neutron detector around while the BTI is the most definitive. Unfortunately, the beginner fusioneer, if he ever makes neutrons, never makes many until much later when technique and gear allow for large numbers. Researchers who are attempting new processes that hopefully produce neutrons for whatever reason and by whatever process, may also not be making many neutrons.

The 3He tube allows real data to be had at very low levels of neutron production that leave virtually every other method in the noise level and allows a weak process to be made stronger through modification and verification of the efficacy of that modification, again, while other detection methods are still in the noise.

The BTI allows the last doubt to be cast aside once a process is thought to be robust enough to apply it over reasonable time frames.

Both systems are costly and need to be applied with some care and controls, but they remain the ultimate arrows in a neutron hunters quiver.

Since this entire amateur fusion effort began in the late 1990's, many systems have been tried and I and others have tried most all of them. Each, in turn, has helped show we are actually doing fusion. There remain many systems that do function, just as always. It remains, however that nothing beats these two above noted systems. The other two neutron detection methods that are very good and good, respectively, are the BF3 and the Boron lined counter. Both require virtually the same level of electronic support, expense-wise. With these, size still counts and size means money. As with all detector heads, lucky surplus buys are always possible for 3He, BF3 and Boron lined tubes.

I have little doubt that someone with good competence could take a larger, 2" diameter 20 inch long, BF3 tube and provide numbers and performance matching a smaller 3He system. We are still talking neutron metrology, background of the user and money.

Neutron detection remains luck of the draw for those on limited budgets, seeking sensitive neutron detection systems. For those who demand the most sensitive systems in a short time frame, money is virtually the only solution and 3He is king.

Richard Hull
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Fusion is the energy of the future....and it always will be
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Re: Inquiry response from LND - 3He tube

Post by Edward Miller » Wed May 11, 2011 11:37 pm

Great post Richard.

I'd only add that Silver (or other) activation and a GM tube is a valid 3rd option. If you get a spike in all 3 then you definitely have neutrons.

1. 3He or BF3 tube and electronics.
2. BTI Bubble detectors.
3. Silver and a GM tube.

Also I spoke with BTI and they said they had a 9 mrem option instead of the standard 33. I think that may be a reasonable option for the lower neutron output fusors, unfortunately I think their minimum order is still 4 @ $150 each and they die out over time.

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Re: Inquiry response from LND - 3He tube

Post by Richard Hull » Thu May 12, 2011 1:43 pm

Thanks for the reminder, Edward. Actually, BTI and silver are final arbiters of fairly healthy neutron production, with silver activation only heralding relatively intense neutron production.

Your listing is probably a good sequential listing of the order in which they might normally be applied from very weak to pretty intense neutron field levels.

Silver activation is much cheaper than BTI, but does demand a superior neutron source that can continuously run for a few minutes, at least, to achieve useful activation levels.

Richard Hull
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Fusion is the energy of the future....and it always will be
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Re: Inquiry response from LND - 3He tube

Post by Wilfried Heil » Thu May 12, 2011 3:48 pm

>Also I spoke with BTI and they said they had a 9 mrem option instead of the standard 33. I think that may be a reasonable option for the lower neutron output fusors

The number on the BTI detector stands for bubbles per mrem, so the -33 is the more sensitive one.

I would also add scintillation detectors to the list, somewhere between the He3/BF3 neutron detectors and the bubble dosimeters.

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Re: Inquiry response from LND - 3He tube

Post by Richard Hull » Thu May 12, 2011 6:14 pm

Reliable, special neutron detection scintillators are near the last or bottom of the list, I would imagine.

Having operated the special and very expensive BC720 Bicron neutron scintillator, (special form - hornyak), in two sizes, it's best efficiency is on the order of 0.2% but its imperviousness to gamma fields rivals the best BF3 systems. (its most wonderful asset)

Another benefit of the BC720 is that it is a fast neutron detector.... (one of the few out there other than the BTI.)

Regular gamma scintillation systems ( BC400 series) are the devil's own work to tune, discriminate and try and convince people you have neutrons while using. Stock scintillators are just not very good neutron systems.

Again, once one's neutron numbers are up and experience is under the belt, most any neutron detection system will suffice.

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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Re: Inquiry response from LND - 3He tube

Post by Steven Sesselmann » Fri May 13, 2011 4:11 am

If I might just add to this thread, I tested my moderated B10 tube with GS-1100A and PRA, and it works a dream. PRA allows for very effective gamma discrimination from the B10 tube, and PRA gives you a visual on the screen, showing you what is happening.

Another advantage is that you record the whole session, so you can adjust the discriminator post experiment with the software. ie. you record gamma's and the lot, and filter it after the event.

B10 tubes do not have a clear neutron peak, but all the gamma's are in the lower energy region, so any pulses over a certain value are neutrons.

Using a spectroscopy system is much more reliable than a rate meter, as with the rate meter you have no idea what it is really measuring. I recently had a case of a faulty connection that was arching at 1500V and what made me realize that these pulses were not neutrons, were the regularity of the pulses when viewed in Intune. Neutrons or Gamma rays for that sake simply don't appear at regular intervals, but a pulse from a discharging capacitor does.

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Re: Inquiry response from LND - 3He tube

Post by jcs78227 » Thu Jun 09, 2011 7:45 pm

Following up on my post of the article on the He-3 shortage: is this the sound of the other shoe dropping?...

Communication Lapse Fueled Helium-3 Gap

"A serious lack of communication between agencies in the Department of Energy caused the present shortage of helium-3, according to the Government Accountability Office (GAO-11-472). DOE’s Isotope Program, which is supposed to provide helium-3 for research and national security uses, was not informed by the National Nuclear Security Administration (NNSA), another DOE agency, about shortages in production of the isotope as far back as 2008. The U.S.’s only source of helium-3 is collection from the decay of tritium during work on updating the nation’s nuclear weapons stockpile. Although some progress has been made in resolving this problem (C&EN, May 10, 2010, page 31), GAO reports that the shortage continues. To increase supplies, DOE has reset its priorities for distribution of helium-3 and is pursuing other sources and alternatives. Specifically, NNSA is determining whether it can buy helium-3 from Ontario Power Generation, which makes the gas as a by-product of electricity generation from a type of nuclear reactor not found in the U.S."

As reported by David J. Hanson of Chemical & Engineering News
June 6, 2011 | Volume 89, Number 23 | p. 33
http://pubs.acs.org/isubscribe/journals ... govc4.html

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Re: Inquiry response from LND - 3He tube

Post by Chris Bradley » Thu Jun 09, 2011 8:21 pm

If you're telling me that there was a "DOE Isotope Program" then it beggars belief that whosoever was responsible for that did not have sufficient comprehension to see that coming. That's incompetence, and to say they 'weren't told' sounds to me like a real lame excuse for screwing it up.

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