On 19/12/2014 23:44, Dave Liquorice wrote:
On Fri, 19 Dec 2014 08:15:24 +0000, Martin Brown wrote:

I think acetic acid would be decidedly bad for them or at least for the
metallic interconnects.

Non acid cure silicone ...

Probably a better choice.

Epoxy glue or acrylic car body filler should be OK provided you never
want to take it apart again.

There is going to be considerable thermal cycling, hopefully not far
short of 50 C (-25 to +20). I think something with a bit of "give" is
in order.

Epoxy can be made a little bit rubbery if you deliberately alter the
proportions to I think be resin rich. It isn't as strong then but it
does have a bit of give. Exeriment on scrap first.

BTW if your two stage cooler has two different sized devices you will
need to interpose a thin ~2mm aluminium plate between them.

I think they are both 40 mm square so will just be "stuck" together
with a thinlayer of thermal compound.

Finding a suitable chamber is looking to be the hard bit. All the
plastic food storeage containers I've looked at so far are milky not
clear. There is a glass biscuit jar in Tesco for £2 that has flatish
sides but is quite large and glass is relatively poor conductor of
heat, so getting the inside cold enough might be tricky.

The Japanese store Muji have some low profile water clear acrylic boxes
that would probably be ideal for this. ISTR Mine was a glass petri dish.

http://www.muji.co.uk/

Oh and the low pressure devices seem to be a repeatable single shot
sort of thing. That is you have a sealed chamber cotaining your
saturated vapour then rapidly reduce the pressure this lowers the
temp and super saturates the inside enabling the tracks become
visible. For a while? Presumably it soon warms back up and you have
to repeat the pressure drop?
On the DIY version I found there is also a "clearing" 150 V DC charge
involved. The Peltier thing I've looked at uses a poly cup or
balloon. I might try as many series connected PP3's as I can find...

I wouldn't worry about clearing it. The chances are you won't have a
source strong enough to cause too many tracks. They appear and rain out
over a period of 5-10s thick ones for alpha and thin ones for beta.

--
Regards,
Martin Brown