X-ray, Gamma BTI bubble 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.
User avatar
Richard Hull
Moderator
Posts: 12434
Joined: Fri Jun 15, 2001 1:44 pm
Real name: Richard Hull

X-ray, Gamma BTI bubble detector

Post by Richard Hull » Tue Aug 29, 2006 3:20 pm

I recently returned from a Teslathon in New York. While there, I had a discussion with a well known fellow, who shall remain nameless. He was positive that gamma rays and neutrons were emitted from running Tesla devices and large powerful air discharges.

I told him that I might allow for x-rays as I had heard of their detection in lightning strikes, though I had my doubts about a tesla coil having the snort to do this. I told him that I was pretty sure that neutrons would definitely not be found in an arc discharge.

I noted to him that the intense and variable electrical fields and electromagnetic impulses in such discharges created so much noise that any electronic detection devices would probably not be of any use in his quest. I noted that there were neutron bubble detectors and that these were noise immune and might be used in the neutron part of his effort.

He disappeared to his car and reported back to me, in short order with three brand new BTI bubble detectors for which he had just paid over $1000.00 !!! The guy was serious............

One was the standard 100BDR unit like we use. Another was the $750.00 "defender" which is capable of 1500bubbles/mrem!!

The last detector I could not believe........It was marked X-ray/Gamma ray!!! Being very familiar with all of BTI's products, I told him that I had never seen this item. He told me it was incredibly sensitive. My interest was certainly peaked.

I was selling some of my four corners U-rock at the flea market that day and he purged the gamma detector of bubbles and we set the item next to a piece of rock I had that was rated at 35kcpm and within seconds, a bubble appeared. Over the next minute, there were 7 bubbles showing!!! I was stunned.

Later in the day, he placed this X-ray detector inside a toroidal valley plane of a large 6KW coil and had the person run it producing 8 foot white hot streamers for about 4 minutes of varied operation. At the end of the run there were about twenty bubbles. Again, I was stunned.

He was going to put the neutron bubble detector in next. I told him it was useless, but that experiment would confirm my prediction. Sure enough, zero bubbles after 2 different 5 minute plus runs. He was very sad at this last result having hoped to prove me wrong.

From all of this, I was determined to investigate this BTI, x-ray/gamma detector when I got back home. I called the head engineer at BTI, Rob Noulty. He confirmed that they do, indeed, make a gamma/xray INDICATOR, (he would not use the word detector). It is designed to indicate or sense the presence of both gamma and x-radiation. When I asked why it was not in their catalog, he noted that the device was not calibratable, nor could it discriminate between x and gamma. Futhermore, it was unstable. Thus, the bubbles are for indication only and bears no bubble/dose relationship to the shortwave EM radiation actually passing through the device. The instability, Rob claimed, comes from temperature variability with use and age. He noted to me that at about 80-85 deg F and above the device would spontaneously produce bubbles, but at 75 degrees was totally usable as a reliable gamma/x-ray INDICATOR.

Thinking back, the outside temp in Rochester was about 78 degrees that day, so the test of my U-rock out of doors was viable. However, the tesla coils were setup in a large metal building which was shut up most of the time for photo ops during coil running sessions. The sun hitting the metal kept it about 10 or more degrees warmer inside. Add to this the fact that the arcs off a tesla coil naturally dissapate many KW in the immediate air surrounding the coil, and you have a combination that could easily create false readings in the particular instance of test performed last Saturday.

So we are back to ....did the coil truly produce x-rays or did the high building temperature coupled with the local air temperature rise at the discharge terminal, while running, cause spontaneous bubbles?

The question remains unanswered, but now we also know that such a device as a noise immune gamma/X-ray detector exists provided it is used in a lower temperature environment.

The device costs only $80.00 and is one of BTIs cheapest bubble detectors. With BTI's $250.00 minimum, the next big order we gather together might include this item for those doing noisy environment gamma/x-ray testing.

Apparently it is just embarrasingly unstable enough and lacking any link to intensity indication that they refuse to list it as a sales item in their catalog.

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.

Jon Rosenstiel
Posts: 1412
Joined: Thu Jun 28, 2001 5:30 am
Real name: Jon Rosenstiel
Location: Southern California

Re: X-ray, Gamma bubble detector

Post by Jon Rosenstiel » Tue Aug 29, 2006 3:38 pm

Very interesting report, Richard. As always, more questions raised than answered.

Thanks for sharing this.

Jon Rosenstiel

User avatar
Richard Hull
Moderator
Posts: 12434
Joined: Fri Jun 15, 2001 1:44 pm
Real name: Richard Hull

Re: X-ray, Gamma bubble detector

Post by Richard Hull » Tue Aug 29, 2006 3:51 pm

Wow, that was a quick response, Jon!! I had not finished writing all of it when you posted. I often blast out 30% of a post that I know will be huge and send it out so it will not be lost and then add to and modify the post, correcting spelling and other errors over a period of up to 20 minutes of "first posting".

You might go over the post again for add-ons. I think I am done with it now, for the most part.

The important thing in my post is that there is now avaialble a noise immune, gamma/x-ray detector on the market that is way more sensitive than a dosimeter or special, sensitive 4000 ASA film pack and lead mask detector. It is instantly indicating and without chemical development issues and delays.
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.

UG!
Posts: 116
Joined: Thu May 19, 2005 8:21 pm
Real name:
Contact:

Re: X-ray, Gamma BTI bubble detector

Post by UG! » Tue Aug 29, 2006 5:31 pm

would it be possable to use those bubble detectors to calibrate a scintilation counter, compairing the readings of both from a running fusor? if so, and if one could be sent to the UK, i might be interested if i have enough spair cash at the time.

Oliver

User avatar
Richard Hull
Moderator
Posts: 12434
Joined: Fri Jun 15, 2001 1:44 pm
Real name: Richard Hull

Re: X-ray, Gamma BTI bubble detector

Post by Richard Hull » Tue Aug 29, 2006 6:55 pm

I assume the scintillation detector you are asking about is pulsing only on fast neutrons as with a bicron BC730 scintillator?

The BD100R, 33 bubble/mrem, BTI neutron bubble detector is good enough to allow rough calibration of an electronic fast neutron detector to a factor of about 20%. This assumes that you take into account all geometry issues.

The UK regs and shipping between Canada and the UK may be such that you would best get a few folks in the UK to go in on it with you. Once in the UK, the distribution could then be handled to buddies within the UK rather simply, I would think.

If, however, you are talking about a gamma scintillator, then no. The gamma BTI indicator bubble device is, as I have said, terrible and bears no reference to any amount or energy of gamma hitting 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.

User avatar
Richard Hull
Moderator
Posts: 12434
Joined: Fri Jun 15, 2001 1:44 pm
Real name: Richard Hull

Re: X-ray, Gamma BTI bubble detector

Post by Richard Hull » Tue Aug 29, 2006 7:10 pm

Geo,

I told the guy that if anything came off the arc discharge and his bubble device was seeing it, then it would be x-radiation and not gamma. Besides, there would be no way to differentiate anyway. Not even a thin lead box would help differentiate as weak 20kev nuclear gammas would be stopped while 70kev x-rays would pass. One would just have no way of testing for which type unless you knew of all processes involved. Only then could a varied thickness lead shield help out..
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.

User avatar
Scott Fusare
Posts: 73
Joined: Mon Nov 17, 2003 10:47 am
Real name: Scott Fusare

Re: X-ray, Gamma BTI bubble detector

Post by Scott Fusare » Wed Aug 30, 2006 9:28 am

Gamma ray bursts associated with lightning discharges detected by space born instrumentation have been known of for many years now. More recently, terrestrial lightning associated gamma bursts have been detected (see paper in files section).

Please note that I am NOT suggesting that the aforementioned Tesla coil was generating gamma radiation. Just wanted to mention this interesting, and obviously electrically pumped, phenomenon.

UG!
Posts: 116
Joined: Thu May 19, 2005 8:21 pm
Real name:
Contact:

Re: X-ray, Gamma BTI bubble detector

Post by UG! » Wed Aug 30, 2006 7:02 pm

yes, i mean a neutron scintilator. your probably right about the shippping, i thught it might be a problem

Oliver

User avatar
Frank Sanns
Site Admin
Posts: 1721
Joined: Fri Jun 14, 2002 6:26 pm
Real name: Frank Sanns
Location: Pittsburgh, PA USA

Re: X-ray, Gamma BTI bubble detector

Post by Frank Sanns » Thu Aug 31, 2006 4:26 am

Yes, thanks for the great article Scott.

I had heard of such results before and have run a few of my detectors during thunderstoms with no positive results. Not even with my 3" solid BGO or my 5" array. The data out shows nada. There are a few possible reasons for it. For one, the storms in Pittsburgh are rarely big lightning bolt events. If there is a critical current or voltage that needs to trigger the gammas then it is possible that the average bolt here is just not beefy enough. The item in that paper that clouds the issue a bit (no pun intended), is the use of copper wire to trigger the lightning stroke. Copper is high enough Z to produce x-rays when bombarded with electrons. I have not had time to really get all of the details of that paper but is it possible that by using copper wire reaching from the ground to the cloud that a man and nature made x-ray tube is produced?

Frank S.

DaveC
Posts: 2346
Joined: Sat Jun 30, 2001 5:13 am
Real name:

Re: X-ray, Gamma BTI bubble detector

Post by DaveC » Thu Aug 31, 2006 8:06 am

I am also doubtful about the validity of the bubble readings. A spark in std atmospheric pressure, consists of a series of successive ionizations leading to an avalanche. So the energy gained between ionizing impacts is not much more than the ionization voltage for the gas... typically around 14-15 ev. That's a pretty strong UV energy, but hardly xray and not gamma.

Getting Xrays in Space from Thunderstorm generated lightning is easy to explain, and getting lightning from cosmic ray generated ion tracks... also seems plausible. But when the electrons start from a conductor in atmosphere, I doubt they can fall through enough potential.. even around a big operating Tesla Coil.

You probably could shield a std. G-M detector with a thin lead box, against low energy xrays and RFI. That would indicate if any somewhat higher energy radiation was being generated.


Dave Cooper

Post Reply