FAQ - Bubble Fast Neutron Detector

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Starfire
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Re: FAQ - Bubble Fast Neutron Detector

Post by Starfire »

Richard - checkout;-

Admin note 160322: it appears that the item previously linked here is no longer available. However, http://bubbletech.ca remains a viable domain, see if you can search for what you're looking for there.
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Re: FAQ - Bubble Fast Neutron Detector

Post by Richard Hull »

I have talked with them about the defender...... 1000 bubbles/mrem!!!!!!

For only $500.00 and it goes bad in a year or two.

They note that its indicating bubbles are much smaller than the 33 bub/mrem unit and are therefore harder to count.

I'll stick with what I have. More reports soon.

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: FAQ - Bubble Fast Neutron Detector

Post by Frank Sanns »

This unit is also a good way to invision what the damage to your body would be like. That is the kind of damage that would be all through your body from the neutrons from a fusor at similar distance. In your brain, heart, liver, and in every cm^3 of your body. The good news is that the human body is very durable (but not indestructable).

Frank S.
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We have to stop looking at the world through our physical eyes. The universe is NOT what we see. It is the quantum world that is real. The rest is just an electron illusion. ---FS
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Re: FAQ - Bubble Fast Neutron Detector

Post by Richard Hull »

Frank is 100% correct. We must not lose sight of the nature of the fast neutron. To get this dose, of course, you would have to lay on the fusor while it is running. Our fusors are very weak neutron producers even during the best runs. This is why we need sensitive instruments to detect and quantify them.

Nothing beats using the inverse square law to protect yourself. Distance, coupled with even moderate shielding makes exposure a non-issue for fusor operators.

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: FAQ - Bubble Fast Neutron Detector

Post by Richard Hull »

The more I use this 33 bub/mrem BTI bubble detector, the more I think ....ALL ......that is, 100% of all other detectors are just not worth owning.

The sole holdout that I would wish beyond the bubble detector is the super sensitive HE3 detector in its large tube iteration that I currently use with fusor IV.

Remember, I own virtually every form of electronic fast neutron detector that is out there and the above is a definitive statement by a long time user and fusioneer. Cold fusion work and the ultra low level neutron detection demands the He3 big tube units.

The average amateur fusioneer could never do any better than one of the BTI bubble detectors. With electronic noise, arc discharges, wiring running everywhere, coupled with haphazard and unstable operation, true neutron output can ONLY be followed with extreme accuracy by the bubble detector! All other detection methods suck to greater or lesser degrees compared to this low cost, no battery, no power, no noise solution.

Again the only way bubbles form in this puppy is in a real swarm of fast neutrons!!!! A deadly field of gamma radiation yield no bubbles. A reactor load of thermal neutrons yields no bubbles. Basically, no bubbles means........No fast neutrons and, thus,.....No fusion.

In a small flux of only 8n/sq cm/second you will see one bubble pop into existence every 110 seconds.

This is not to denegrate counters or systems used by others or myself in the past. It is rather a story of forgetting that noise ever existed, of forgetting about background counting and determination, forever, about saving approximately $500.00 over a rem ball, about not being fooled by balky instrumentation operated at the hands of an amateur.

I just removed the batteries from all the neutron instruments I own! I just won't be needing them in the immediate future now that I am armed with the NIM bin based He3 counter and the BTI bubble detector.

Bubble detectors used to be expensive, short lived, high flux only and messy to work with. Most of these disadvantages have disappeared. There are only two remaining issues.

First, and of the least concern, is the narrow temperature range of operation (~45 deg F to ~92 deg F) and the need to adjust readings based on ambient temp at time of exposure. (note - There are tempcompensated units avaialble...$$)

The big negative is that you need to spend about $120.00/year to keep a fully action ready BTI bubble device on hand. For those who work for a living and are not saddled with kids, a mortgage and two car payments, the $120.00 is chump change to be positive about neutron outputs in fusion devices. Admittedly, the guys at BTI said the time of valued usage varies from 10 months to 18 months based mostly on temperate storage.

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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Adam Szendrey
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Re: FAQ - Bubble Fast Neutron Detector

Post by Adam Szendrey »

Right now, the only, and single, disadvantage i see is the limited lifetime, otherwise it's really great, and rather cheap, and indeed an extremely reliable indicator of fast neutrons. Thanks for the info you supplied Richard.

Adam
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Re: FAQ - Bubble Fast Neutron Detector

Post by Verp »

This thread has me thinking about if it would be possible to make this sort of detector on my own. I just need to watch my tendency to get quixotic and take this beyond the area of diminishing returns. I once thought it would make sense to build a low whistle one octave below the standard D pennywhistle, rather than spend too much on a new one. The project got out of hand and I now own a drill press (not to mention all the various plastic and metal tubing for the body of the whistle) that costs more than one good high quality low whistle!

I have worked with gels in the past, through cooking and having poured my own agar based media into petri dishes and culture tubes. (I was making clones of local wild edible mushrooms I had collected.) I think some experimentation with the right gel will be needed to find the right ratio of liquid to polymer that is strong enough to prevent the liquid from bubbling, but flexible enough to bubble at the increased vapor pressure of the liquid caused by a high-energy neutron hit.

My first thought was to use agar, as that is readily available gelling agent, or other polysaccharide (sugar polymer) used to make growth media, but I realized even gelatin would work with a small bit of preservative that doesn’t mess up its ability to gel. If the vapor pressure of water isn’t high enough, another possible gelling agent is polyacryamide, which can handle many solvents that the natural gelling agents can’t and is available as an electrophoresis gel. It is polymerized in situ when the gels are made, but acryamide is a carcinogen and neurotoxin, complicating things.

The only reason my first thought was to use agar is that it is the gel I’m familiar with using at many different concentrations. The only reason it is preferred to gelatin is that microbes don’t eat it up as quickly. As I don’t want to grow things in the first place, I would use inexpensive gelatin in water with a bit of preservative if I was to make a very large detector. If a higher vapor pressure solvent were needed, I would make a small detector using polyacryamide. The gel used to make transparent candles might work, also. The liquid, I believe is kerosene or some other petroleum distillate, would probably be easier on the roughing pump than say water, if the pump was used to reduce the pressure in the detector.

Speaking of getting quixotic and going overboard, I was thinking of using a large gelatin or candle gel detector as the neutron shield of a high output reactor. The pattern of the bubbles around the fusor might give clues to the pattern of neutron emission. A concern might be if the detector were too deep, would the weight of the gel make the detector less sensitive toward the bottom? I might get around that by using less of the gelling agent at lower levels in the detector, but that might involve a lot of experimentation and may not work. I could just make the detector as discrete layers too thin to be strongly effected by the depth of the gel.

As far as figuring out the proper pressure to run the detector at, I would guess that an absolute pressure gauge that reads up to ambient air pressure could be used to find the pressure at which the gel starts to bubble. I would then use ambient air pressure to collapse the bubbles, and finally bring the pressure down to just above the pressure it bubbles at without high-energy neutron hits.

Rod
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Re: FAQ - Bubble Fast Neutron Detector

Post by Frank Sanns »

Rod,

You might try to use poly vinyl alcohol in distilled water to bring the viscosity up to a desired level. A little fumed silica (Cabosil) could be added to keep the gel in place after the bubble forms. It is a thixotropic agent that will gell fluids that are not moving. Once they move a little, the visocity drops only to jump up again when the movement stops. A little benzalkonium chloride (Bactine) can be added to stop microbial growth. For the low boiling solvent that will vaporize to form the bubble, I think butane was the choice in the early tubes.

Frank S.
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We have to stop looking at the world through our physical eyes. The universe is NOT what we see. It is the quantum world that is real. The rest is just an electron illusion. ---FS
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Re: FAQ - Bubble Fast Neutron Detector

Post by Verp »

Frank,

Thanks for the input. I am familiar with benzalkonium chloride as quaternary ammonium detergent or “quat” as the active ingredient in sanitizing cleaners (as well as in Bactine) so price and availability are not issues. I am familiar with polyvinyl alcohol as an ingredient in some insect specimen mounting media. I remember it was a real pain to get into solution, but seemed to have no real toxicity issues. If gelatin is cheaper than polyvinyl alcohol and works well, I will try that with the weakest solution of quat recommend as a biocide, probably the concentration used as an algaecide in lab water baths. I’m not trying to kill tough spores and viruses, just keep organisms from starting families in my detector.

If a low enough pressure will make the detector work with just a water based gel, I won’t worry about how much butane or other low vapor pressure fluid to introduce, getting rid of another variable.

My understanding is that a good roughing pump tends to remove material with a higher vapor pressure than the oil, especially with a good sorbent to keep the oil clean, so careful use of valves should keep water contamination of the vacuum system low when I pump down the detector. I could just use a large bellows or piston to reduce the pressure in the detector and simply make sure there is no air space when I first fill the detector.

Perhaps the right amount of fumed silica would be the maximum amount that doesn’t make the water too cloudy, then add just enough gelling agent to keep bubbles from rising and the silica from settling. I’ve seen Carbosil for sale as a thixotropic agent for use with fiberglass resins as a filler, so it shouldn’t be a big issue to get it for a reasonable price.

Fumed silica got me thinking about sodium silicate and silica gel as gelling agents, but I am just brainstorming. An inorganic gel would not support or be broken down by microbes, though.

I will work on this some more, maybe after getting closer to actually making neutrons.

Rod
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Re: FAQ - Bubble Fast Neutron Detector

Post by Alex Aitken »

"I think some experimentation with the right gel will be needed to find the right ratio of liquid to polymer that is strong enough to prevent the liquid from bubbling, but flexible enough to bubble at the increased vapor pressure of the liquid caused by a high-energy neutron hit."

Hmm. This was not my understanding of how the device worked. I was under the impression it was a suspension of droplets above the boiling point and under no extra pressure from the matrix. What's stopping the droplets from expanding is the lack of a surface to nucleate on. I was furthur under the impression that the point of the matrix was to keep the droplets seperate from eachother, seperate from the walls they could nucleate on and prevent the nucleation effect when it happens from spreading to the other droplets.

I suspect the chemicals need to be exceedingly pure from dust and solids.
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Re: FAQ - Bubble Fast Neutron Detector

Post by Richard Hull »

It's all a big secret and they aren't tellin'. Feel free to muddle along trying to "guess engineer" or "roll your own". All that remains is consistency and calibration. I figure the latter are fully 50% of the effort.

For a fact, they mass irradiate and "bin" each detector based on bubble numbers so it ain't even slighly precise at the manufacturing end. What you get is a carefully cal'd luck of the draw, pick o' the litter, bubble detector that is repeatable and reliable.

If you have a hot neutron source, (they used a chalk river reactor), the chemical know-how and access to ultra pure chemicals you should be able to make up a hundred of so and then irradiate them and "bin" them based on performance just as they do.
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Fusion is the energy of the future....and it always will be
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Re: FAQ - Bubble Fast Neutron Detector

Post by Jon Rosenstiel »

Just got off the phone with these guys...placed an order for the BD100R, 33bubbles/mrem model. Should arrive here before xmas. (Maybe it'll be under the tree)?

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Re: FAQ - Bubble Fast Neutron Detector

Post by Richard Hull »

John,

Fantastic! You must report to us all the details once you put it to use. You WILL love it and hate it.

You will love it because it doesn't lie. You will hate it because it doesn't lie.

I found that after spending a mint and jumping through numerous hoops to obtain the finest electronic neutron detection system around for fusor IV , (He3 system), that the bubble device was much more reliable if not quite as sensitive. It is a snap and a no brainer to use.

My plus ultra He3 system is just clicking away like gang busters and with each upward inching of the voltage control the count is noticibly more active. At 29kv I am getting nearly 200-300 CPM with the He3 but the bubble detector is showing about 50-80,000n/sec., isotropic!

Damn it all! The truth will out.

Some tips when St. Nick drop the thing down the chimney.

Operate and store it within the temp range specified. keep it out of the fusor area until your fusor is cruisin' along at the point that you can satbilize it easily for a minimum of five minutes. Don't try for max output on you machine. Shoot for stability, though this is not actually madatory as the thing is a perfect fast neutron integrator. With stability, your actual final figure will be more representative of the entire run.

Once in your comfort zone with the fusor. Get a ring stand as used in chem labs with a test tube clamp and place the base of the BTS detector at least 4" away from the shell (to avoid radiant heating of the detector) and then open the pressure screw until the screw goes sloppy. (it will be retained).

Start a timer immediately and then run for a period that you like. Watch the bubbles pop into existance. Cool!

DO NOT LOAD THE THING UP WITH BUBBLES. End the count when the device appears to have about 30-40 bubbles in it. Note the time and total exposure period. immediately take it out of the fusor area.

Counting - the nightmare begins.

Surely you can count 30-50 bubbles??? Yes and No. You can count 5 times and get 5 different counts.........!! BTS recommends you have a buddy or others count and do a statistical reduction.

I have found that carefully and slowly rotating the device and counting as in a spiral staircase works for me. Log your result with pencil and paper and then screw the screw all the way back it to just good and snug. BOOM, the bubbles are gone. As age sets in, they will not flashout like when new and a few minutes will be needed to ready the device.

Enjoy! And remember us out here. Give a full report, especially personal comments, problems, delights and thoughts on the device.

Unfortunately, the device is so good that your rem ball might fall into disuse or be religated to backup or confirming actions.

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: FAQ - Bubble Fast Neutron Detector

Post by Alex Aitken »

This is probably making a very simple detector over technical but....

Ive heard of laser counters for the bubbles and they seem like rather technical devices. If a light was shined through the tube while in operation though, with the result being read by a photo cell wouldnt the apearence of each bubble result in a noticable change of level of the light output? If something monitored the apearence of each bubble that sounds easier than trying to count them all afterwards and you do have the physical evidence of neutrons to check after the experiment.
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Re: FAQ - Bubble Fast Neutron Detector

Post by Jon Rosenstiel »

Received an early Christmas present today, via FedEx. The BD-100R arrived packed in an oversized box containing bubble wrap (appropriate) and Styrofoam peanuts. Eight days from order placement to holding the detector in my hot little hands. Not so bad, I’d say.

The double ouch was the import/shipping cost, $100.00!

Evidently, one must ask for the temperature response curve when ordering, as none came with it. I’ll have to fire off an e-mail next week requesting the curve.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
UPDATED 12/18/04.....
After posting this (late Friday evening) I sent an email to BTI. The temp response curve was in my inbox this morning (Saturday), with apology.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

With any luck I’ll be able to give it a test run this weekend. I’ll post my findings here.

Based on Richard Hull’s experience with his bubble detector, I expect that my neutron numbers will be nowhere near as high as my Ludlum (just recently re-calibrated) rem ball says they are. I’m preparing myself for a 65% drop in total isotropic emission rate. I’m afraid the truth is gonna’ hurt!

Stay tuned….
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Re: FAQ - Bubble Fast Neutron Detector

Post by Jon Rosenstiel »

I finally got some time this afternoon to try out my new bubble detector. This thing is SWEET! Watching the bubbles “pop” into existence is pretty cool. (Better than a lava lamp)! I got a few runs under my belt, but I still need time to sort out the best way count the bubbles. So far, the best method for me is to shine an LED flashlight into the end of the detector, then count the bubbles as I rotate the detector back and forth slightly. (To make sure I haven’t missed any hidden bubbles).

BTI recommends using a video camera with macro lens, then marking the location of the bubbles on the monitor face. (Similar to cell counting)

After Santa delivers the new high-zoot digital camera I asked him for I think I’ll try taking a photo of the detector and see if I can count the bubbles on my computer monitor.

For this afternoon's tests I used a temperature correction factor of 1.4, as my lab was a balmy 27C.

I’m not going to post any data until I become a little more familiar with this device and am more confident and consistent in my bubble counting ability.

FWIW: Roughly speaking, my Ludlum rem ball detector is giving a TIER (Total Isotropic Emission Rate) approximately 40% higher than the bubble detector gives. Not nearly as bad as the 65% I was expecting.

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Re: FAQ - Bubble Fast Neutron Detector

Post by Richard Hull »

Jon, you are experiencing about what I did. I was getting about 50,000- 70,000 isotropic with the BTI bubble device and was used to seeing about 125,000 using the normal BF3 route with my Eberline PNC-1. It is nice to know that we are in the same ball park.

According to the folks at BTI, the accuracy can be in the 5% region. Therefore, I think we need to look at wrong assumptions in the input part of our old neutron counting. The only thing I can think of is the efficiency of the BF3 is a bit higher than .5% and I think the 1% figure is also a bit low.

It all comes back to just how efficient the moderator is. A BF3 tube or He3 tube at a decent pressure could easily be 10%-25% efficient if you could warrant that every neutron entering it were truly at thermal energies. With the rem ball, this is sort of warranted to be the case.

Thus, the rem ball is averaging out dose much like the BTI. So if a rem ball is showing 10mr/hr, the center of the ball is saying that the entire ball is being bathed in a flux of 80n/s/sqcm. If the ball is 30 cm from the fusor then 11,309 X 80 or ~900,000 neutrons/sec is the isotropic emission rate. The tube efficiency is not a factor due to the mated meter ball combo, being calibrated. (the 30cm is center of fusor to center of rem ball). Given this set of circumstances, the BTI detector could supply a correction factor, (scientific term) or a "fudge factor", (real life term), if placed at the same range.

With the BTI, we should be able to establish a calibration factor for any BF3 or He3 system. Once we get the counters in agreement with the bubble detector by using this factor, we will not be so pressed to buy another bubble device when this one blinks out in a couple of years as our electronic numbers will then be good and reliable. This factor would be "counter specific" and would make weak tubes, funky electronics, variable moderation efficiency, oddball and varying geometries and other such variables found counter-to-counter a non-issue.

The BTI bubble device is just too cool as it is free of all the above CRAP!

Again, absolute counting is a bear. Certainly, I would carry a bubble detector to a friends house to check his neutron numbers long before I would ever grab an electronic counter.

I look forward to your future report. Please put it in its own separte posting with an easy search title like "bubble detector results" or something like that. Post a pix or two of the setup.

Richard Hull
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Fusion is the energy of the future....and it always will be
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Re: FAQ - Bubble Fast Neutron Detector

Post by Jon Rosenstiel »

Richard, got a question on counting the bubbles.

I've noticed that some of the neutron produced bubbles are quite small, but they do seem to be real neutron bubbles because they disappear when the compression screw is cranked down.

Seems to me that ALL bubbles should be counted if they are produced by neutrons, no matter how small. What are your thoughts on this?

About the high readings the rem ball is giving….. I recall reading somewhere, not sure if it was the Songs list, or Intranets.com, or this list, but it was mentioned that the various manufacturers of our rem ball devices tend to shove them out the door with a fairly conservative calibration. (They want to play it plenty safe, don’t want anyone “overdosing” on their watch).

I wouldn’t think that what we’re seeing can be totally attributed to the manufacturers “playing it safe”, but it may be at least a part of it.


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Re: FAQ - Bubble Fast Neutron Detector

Post by Richard Hull »

Jon,

Count all bubbles just don't count "Fizz" bubbles which are truly very small. The small bubbles might be one third the size of the largest bubbles. Take another good look at the photos in the original post above. You will see some small bubbles there too. Basically, any bubbles not there when you started are neutron induced.

The conservative ratings on the REM balls might just be the answer. We need the fudge factor that the BTI device will supply.

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: FAQ - Bubble Fast Neutron Detector

Post by badflash »

I've been e-mailing Rob Noulty, Ph.D of Bubble Tech (good people) and asked about the shelf life of the detectors. I've attached a paper he sent me that give the conclusion that you can use these detectors for 2 years if they are not temperature compensated and you close them up when you are done. Once the bubbles don't go away, it is time for a new detector.

Another cool note is that the bubble count should be done 2 hours after the detection is done. The bubbles continue to grow.

I was going to put off ordering until after I got my deuterium, but there is no longer any reason to wait. I'm not putting this project off that far, and the deadline may help.

Thanks to those that came before me, as they are willing to support us. Normally they won't sell just one detector, but for us they make an exception.
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Re: FAQ - Bubble Fast Neutron Detector

Post by Richard Hull »

Rob was a big help to me in the beginning, as well.

He also informed me that when the bubbles won't go away, you can still use the detector as it will still record perfectly!! You just need to subtract the pre-existing bubbles. Naturally, the item is totally shot when the initial bubbles are so numerous that the counting effort is a lose-lose proposition.

As the device gets older, the bubbles will naturally take longer, after recompression to go away, but all bubbles should be gone within 10 minutes. Those that remain are more or less permanent.

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: FAQ - Bubble Fast Neutron Detector

Post by Alex Aitken »

I dont think direct links on espacenet work, but pick an archive and have a read of US 4,143,274.
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Re: FAQ - Bubble Fast Neutron Detector

Post by Richard Hull »

Additional BTI bubble detector data based on a paper study of the expected life span of the buble detector. A synopsis follows....

1. Always keep the detector stored in its shipping tube.
2. Always store the tube near its median temp range and never at extremes
3. The absolute calibration of the device is only warranted for about 6 months.
4. in the sensitive models under high flux or lots of bubbles per use, the device sensitivity increases.

For longest life...1 to 2 years.... obey all of the above plus........
Try to use the detector a minimum of monthly, but preferably weekly to count neutrons and preferably not a high flux. The detector likes to be used frequently to count low bubble numbers and get depressurized and repressurized.

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: FAQ - Bubble Fast Neutron Detector

Post by badflash »

Just ordered mine. It shouldn't be long now before I can try it out...
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Re: FAQ - Bubble Fast Neutron Detector

Post by Richard Hull »

************* UPDATE 2006 ***********************

BTI now has a minimum order of $300.00 of their product!

The BTI model BD100R (33 bubble/mrem) detector is still $75.00 each meaning you must order 4 or more.

In addition the shipping and US/CANADA boarder transport fee and handling fee is on the order of $150.00 (this is for one or four dosimeters). What the hell ever happened to the joy and promise of NAFTA that Clinton pushed through? Seems like that little short dude Ross Perot was right........ Nafta would ultimately only allow jobs and massed units of cheap products to go over the boarders unfettered, but not personal american one off goods. (screwed again).

In future, unless you can bring four guys in with you, figure on dumping about $450.00 for a bubble detector dosimeter.

More sadness as no one wants to be saddled with only making $225.00 per order!

These still remain the best, most sensitive and cheapest fast neutron detectors out there, in spite of the new "ream your butt" pricing.

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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