cloud chamber

[jenny walter]

We have an old Townson & Mercer cloud chamber that teacher would like to dust off and use for demo, problem is we no longer have instruction manual, would anybody out there have an instruction manual that they could photocopy and fax to me. Appreciate any offers, Thanks
Jenny Walter

[Matt_Coffs]

Different model but it might still be useful.
http://www.<URL removed, see forum rules>/z_pdfs/ap4660-001.pdf

[jenny walter]

Thanks Matt, but my old townson & mercer model looks nothing like this new one.
Regards
Jenny Walter

[Ocker]

Some have a container on bottom to fill with dry ice others have a spike designed to go into a thermos flask full of dry ice to get bottom cold also there should be a felt ring below top that you use a wash bottle full of Metho/Ethanol to saturate felt ring

[Mostly_microbes]

We have an old Townson & Mercer cloud chamber that teacher would like to dust off and use for demo, problem is we no longer have instruction manual, would anybody out there have an instruction manual that they could photocopy and fax to me. Appreciate any offers, Thanks
Jenny Walter

I'm adding to this old thread in case someone else has the same issue.
The Townson & Mercer cloud chamber that we have is a 'spray style' in that it relies on a pressure change, rather than a temperature change for the alcohol to vapourise. I don't have the instruction manual either, but broadly, the instructions for use are:

• 1. Give everything a clean! Ours was coated in about 2cm of dust and grime.
  2. Undo the nuts holding the top ring and glass plate on and take them off. Also take off the metal plate underneath. Ours has concentric rings to measure distance on it.
  3. Saturate the felt pad underneath with alcohol. I used Isopropyl alcohol.
  4. Put the metal plate, glass plate and top ring back on and tighten.
  5. Turn everything on. Ours has a lateral light source attached.
  6. Attach a bellow or plunger to the gas nozzle on the side.
  7. Push the plunger in, you should get vapour forming inside when the pressure is released. It is short-lived.
  8. Place a radioactive source near the vapour, or just watch for background radiation trails.

Cloud chamber.jpg

[bigmack]

Woow , thanks for posting MM, that is an amazing old piece of kit .I guess the wire with the plug on it is the "Mopping voltage" .
Curious what voltage it is .Some old Cloud chambers used 90v batteries ( which you can't buy anymore) .would give you a nice tingle if you have sweaty hands but not dangerous

7. Push the plunger in, you should get vapour forming inside when the pressure is released. It is short-lived.

That's , interesting . I made one out of an old jam jar and found the same thing . The radiation trails are only visible for a few seconds then it's gone after each time you change pressure .The version I made had a vacuum created when you pulled on a plunger . It is interesting that increasing pressure then quickly releasing it will do the same thing .Thanks

[RosalieL]

If anyone doesn't have a cloud chamber, I found this when looking up things for science week. I haven't tried it out for myself yet so if you give it a go let me know if it's any good!

https://spookyactionbook.com/2012/10/15 ... -detector/

[bigmack]

Thanks Rosalie .
It could work . I'm just skeptical about the can of air . I have never noticed that they get cold .Maybe its an American product .
But the idea makes me think that Freeze spray used for electronic fault finding might also work .That stuff definitely gets things cold .
I also find it interesting that there is no Mopping voltage in that design . Most cloud chambers either use an external voltage from a HV battery or power supply or you rub them with a cloth that creates a static charge .

EDIT: it does seem that Laser Air cleaner sold in Aussie has the 1,1-difluoroethane in it .
But check out the SDS . Might want to leave the windows open .

SDS Aerosol Air Duster - CL-1827F_KongStar 1.pdf

Here is an other link that may be helpful .
viewtopic.php?p=40349#p40349

[RosalieL]

Thanks bigmack! I'll revisit this if I ever get around to trialling it... Sadly we didn't have enough student elect physics for next year so we won't be needing to do a cloud chamber for a while...

[bigmack]

Sadly we didn't have enough student elect physics for next year

That's crazy to hear Rosalie.

[RosalieL]

Sadly we didn't have enough student elect physics for next year

That's crazy to hear Rosalie.

We're a fairly small school and for some reason it's not a particularly academic cohort coming into year 11 next year. Hopefully the following year will have more seniors choosing science subjects.

[Mostly_microbes]

I don't have the instruction manual either

I found the instruction manual for the Townson & Mercer Cloud Chamber, while looking for something else!
Sometimes I'm glad the old Labbie never threw anything away (but usually not)
Judging from the look of the manual, and the defunct supplier name, I'm guessing it's from the 1970's.