bubble chambers

[Doug Coulter]

Thomas Rapp sent me a couple of nice papers on bubble chambers that look within reach of an amateur, which I will attempt to sanitize somewhat and put up here.
One is a propane based design and runs at a few bars, but the fascinating one is one that runs at STP and room temperature! In the latter design the bubbles are from
a CO2 solution in hexane and the temp gradient is done by room temp at the bottom, and a heating lamp at the top. Since in either case the working fluid is hydrogenous, this
bodes well for it being a real time neutron detector, and might solve the neutron beaming detection issue Tyler and I are talking about on another thread here in a
really slick way. Supposing you could put this together with something like a pair of glass plates and make it the size of a sheet of paper and set it over the fusor, you
should be able to see where the neutrons are coming out with a video camera on it (or a mirror) so you don't have to get into the rad field to observe the actual pattern.

The author claims the C02/hexane thing works continuously for 15 min or so without having to re-solve the CO2 that bubbles out.
One wonders if any clear carbonated fluid might work -- beer, anyone?

For those who have access and can't wait they are:

Propane bubble chamber in a high magnetic field, RevSciIns, vol 28 #2 feb 1957,
Larry O. Oswald
and
Improved continuously sensitive bubble chamber RevSciIns vol 32 #8 Aug 1961
Ryuhei Kato

I am wondering if that if the need is for shorter time use, you don't need the temp gradient on that latter one, in which case making what I have in mind would be really easy,
mainly getting the container clean enough to not seed bubbles itself and making it easy to fill and drain to get a "map" of neutron outputs.

[Doug Coulter]

We're not immune to humor here, and Bill just sent me this which had me falling off the chair, after we discussed it today FF.
It's almost right -- actually you want to heat up the beer (super critical superheat) for this to work, and you know, I'm going to try it with real neutrons. We didn't get much of anything off a very hot
(torbermite) ore sample, but I suspect gammas don't work anyway (not enough absorbed energy per length) -- and the alphas/betas wouldn't get through the bottle anyway.

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Miller High Life Neutron Detector

This paper presents a novel way to detect high speed neutrons using a super saturated ethylated carbonated “Boilermaker” mixture. This has a dual meaning in that the neutrons cause the mixture to boil and the resultant mixture can be used as the popular drink “Boilermaker”

Bubble chambers make use of super saturated mixture that has one or more constituents that is near its vapor pressure or boiling point. When the mixture is stable at near boiling conditions, the slightest input of sudden energy, may cause one of the suspended gases to come out of solution and create a “bubble”. It is this bubble that creates an artifact of a recent neutron or proton collision. The rate of bubble production in the body of the mixture is proportional to them rate of proton/neutron collisions with hydrogen atoms contained in the mixture.

The method as originally proposed by Doug Coulter, uses a chilled Miller High Life beer, In a clear glass bottle, with label removed. This revised method proposed the incorporation of miscible ethyl or grain alcohol to increase the density of the mixture and increase the probability of hydrogen atom collision.

To prepare the mixture, bottles of Miller High Life (MHL) are soaked in a tepid solution of water for an hour or two until the labels are easily removed. Be careful not to use hot water as this may “skunk” the mixture and there is a secondary use for the mixture. The unopened bottles of MHL are refrigerated in a refrigerator, along with a bottle of ever clear or grain alcohol. The refrigerator is set for a temperature of 31. 4 degrees (made up) to cool the beer to its minimum temperature, without breaking the bottle. Miller beer contains 6% alcohol by volume and drops the freezing and triple point of the mixture as compared to plain water.

Since many bottles of MHL may be required to determine spatial orientation of neutron production, it is suggested that a mini fridge be placed near the experiment. This must be of the compressor design rather than a pettier cooler, as the later will not reach the required cooling point.

Once the refrigerated bottles have reached the required temperature, they are ready for mixture. The mixture will have a limited life and must not be mixed until you are ready to measure neutron production. Prepare the MHL by opening it with a “church key”. Pour a little in a glass and sample it. (Do not place your lips on the bottle as saliva may cause spurious bubbling). Replace the removed volume with grain alcohol from the chilled bottle. This is a trial and error method and one must be careful not to use too much grain alcohol as this may have disastrous consequences to both the mixture and the mixer.

Once a trial mixture is prepared, situate it close to the neutron producer. Position an ultraviolet light such that the beam shines through the mixture. The UV light produces fluorescence from the suspended yeast particles in the mixture. This helps in the identification of bubbles. It is also a great “mood light”. Turn off unnecessary room lights and begin neutron production. You might want to put some appropriate music on the stereo, such as “Neutron Dance”, by the Pointer Sisters. You may also want to enjoy the moment with your favorite person.


In keeping with the conservation movement we recommend that you use the left over mixture to wet your whistle. Several cautions to the experimenter, though. Don’t run the experiment too long or too many times as the data recording may become difficult to do. Also, if you’re running something like a fusor or borehole tube, lethal voltages are involved. If you can’t count the number of bubbles or the number of fingers you have, it’s time to stop the experiment. Remember MHL bottles are glass and are easily broken.

Bill F