SparkChambers
 

Anyone ever built one, to show the trajectory of Cosmic rays?

They were used up until the 1960's so it's a vintage instrument/machine.

There is a great deal about them on the net from Universities and I have
obtained the bible on them, 'Bubble and Spark Chambers.' published in 1967.

I am toying with the idea to build but among other odd things required would
be a cylinder of near pure helium or argon bought from
the British Oxygen Company, although air has been used very
inefficiently.

PS. 'Bach with sparks' has not been neglected but it's on the bach burner :D
for a bit, with a QCWDRSSTC being built in between.

Re: SparkChambers
 

Argon certainly used to be a very great deal cheaper than helium. If there's a diving shop or a welding supplier near you then you might get a better deal on small quantities of gas from them. If you're running close-to-breakdown voltages in air then do watch out for corona production of ozone. It really isn't good for you.

Cheers,

GJ

Re: SparkChambers
 

You can get reasonably good helium from Card Factory in their balloon kits.

Re: SparkChambers
 

I thought the helium from the balloon shop contained added air to prevent kids from suffocating.

You can however get argon from Halfords.

Re: SparkChambers
 

Most diving shops will likely only supply compressed air and possibly nitrox (compressed air with additional oxygen added). Some of the more specialised shops may have helium for use in producing trimix (oxygen/nitrogen/helium) but in my experience they would only be likely to supply this into a properly certified and tested diving cylinder and would probably also want to see a suitable diving qualification to show that you are qualified to use the gas they are supplying you with.

Re: SparkChambers
 

Apparently not as I know someone who killed themselves with it :-/ (he had spinal cancer for ref)

Re: SparkChambers
 

I thought there were small disposible cylinders of argon for people with hobbyist mig welders. They certainly won't work with a breathable amount of oxygen in them, that would certainly ruin any attempt at welding. Haven't seen them in Halfords but you could try machine mart.

I've bought various supplies and equipment from this firm over several years and found them trustworthy.

https://www.r-techwelding.co.uk/weld...t/welding-gas/

You'll need a regulator as well.

My smaller Argon cylinder is about £90/year to rent the cylinder itself from BOC, plus about the same for a refill. It's size 'Y' and contains 20 litres at 200 bar. so about 4000 litres at atmospheric pressure. And you definitely need a good regulator. These pressures are dangerous. Helium is much more expensive. Argon is just collected from liquified air and is essentially a recycled resource.

Take care, it is heavier than air and is an asphyxiant

David

Re: SparkChambers
 

Thanks all for suggestions etc. I had forgotten that Argon is used in welding so is
cheap and plentiful. Argon requires a higher working voltage than Helium but that would not be a problem.

Just air has been used but that generates Ozone and Nitrous Oxide,
but being in a small sealed chamber doesn't present any health problem.

As Helium is getting scarce now I believe that most used for balloons does contain some air.

Re: SparkChambers
 

balloon helium

https://www.gas-uk.co.uk/balloon-hel...tres-1464.html

Argon

https://www.gas-uk.co.uk/argon-pure-5-litre.html

A Wilson cloud chamber may be easier to construct.

Re: SparkChambers
 

BOC list their balloon gas as 97% He, 3% air.

Re: SparkChambers
 

Argon also has the advantage that it's less good at escaping from home-made 'gas tight' chambers than helium. The latter is well-known in the business for being among the most difficult gases to contain.

Cheers,

GJ

Re: SparkChambers
 

Yes it certainly is, but requires dry ice each time it is used.
That rather put me off it.

Re: SparkChambers
 

Pure liquid helium is used for cooling the superconducting magnets in medical scanners and the like.
Despite thermal insulation it continually boils of, and some of this is captured and sold as "balloon gas" which therefore contains a variable proportion of air.
Supplies of helium are limited as it forms very slowly due to natural radioactive decay deep underground, it comes to the surface mixed with natural gas from which it is extracted and sold.
Argon by contrast is relatively common, air contains nearly 1% argon. vast quantities of air are liquified to produce liquid oxygen for medical purposes and industry, and liquid nitrogen for cooling. Argon is thus produced.

If you want argon, have a look on-line, several suppliers offer it cheaply, for example by including free cylinder hire subject to purchasing one refill a year.

Re: SparkChambers
 

This is what started me off on spark chambers, a small directional detector I am building with rotating detectors in pairs, one of which is lead shielded to ensure no local radiation is lit up on the led's.

Re: SparkChambers
 

Hi.

I remember reading that helium is able to permeate through glass such as in valves and impair the vacuum. Is this a real possibility if the valve is exposed to helium?

Regards,
Symon.

Re: SparkChambers
 

I guess that will come down to the numbers and I don't know those I'm afraid. The fact that the valves run hot won't help (I believe solids tend to become more permeable as their temperature rises). Any micro-cracking around e.g. glass-to-metal seals would be a particular problem. And most people are surprised to see how thin the glass envelope of a valve is, usually the first time they break one.

All that said, I wouldn't expect occasional exposure to small amounts of helium to bother a valve at all. Hot filament ion gauges are made of glass after all https://www.lesker.com/newweb/gauges...m#Hot_Filament. Operating a valve day and night in a high-pressure helium atmosphere might be a very different thing though. But at least we would only have to worry about ion current and eventual gas breakdown. Helium is extremely unreactive and I wouldn't expect it to chemically poison cathodes the way air or moisture or many other gases can.

Cheers,

GJ

Re: SparkChambers
 

After some recent reports, I thought any stray helium made a bee line for the nearest iPhone or iWatch in order to percolate in and disable it!

David

Re: SparkChambers
 

Know all alert "I believe solids tend to become more permeable", maybe they do, but glass isn't a solid, it's a super cooled liquid............ I'll get my coat.

Re: SparkChambers
 

... which may mean it's even more permeable!

Re: SparkChambers
 

True. I should have said 'condensed phase materials'. Fact is, though, that gases diffuse into one another faster at higher temperatures too. So really I should just have said 'stuff' ;D.

Cheers,

GJ