

Building a Cloud Chamber (Cosmic Ray Detector) - nkurz
http://www.amnh.org/education/resources/rfl/web/einsteinguide/activities/cloud.html

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todd8
I first read about making one's own cloud chamber as a kid. I used to read old
issues of Scientific American for the Mathematical Games columns written by
Martin Gardner, which I highly recommend, and the Amature Scientist column
written by a series of authors over the years, starting in 1928.

The projects were amazing. My favorites to read about were the seismographs
and telescopes. Several cloud chambers were described, the first in September
of 1952. These were of varying complexity, some made from peanut butter jars,
etc.

I believe that these columns are still in print in various forms (collections
published in books and on the internet as reprints from Sci. American). Not
all of the project could be undertaken lightly. Particle accelerators, x-ray
machines are two risky ones that come to mind.

The diagrams that accompanied the columns were notable for their clarity and
ability to illustrate.

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lm741
These are really easy and fun to put together. I'd highly recommend it for a
weekend project.

Here's one that I built running with a sample of Americium 241 from a cheap
smoke detector: [http://bit.ly/UDWpc0](http://bit.ly/UDWpc0)

Here's a different one running with a bit of Thorium containing lantern mantle
[http://bit.ly/1Annrp5](http://bit.ly/1Annrp5)

You can also try with thorated tungsten welding rods and other household
sources of radiation.

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nkurz
I came across this article while researching whether Coleman lantern mantles
are still radioactive. Putting a mantle close to this detector would be one
way to find out. Traditionally, lantern mantles were made with Thorium to
produce a brighter and whiter light.

It turns out that most current mantles (including those made by Coleman) have
switched in the 1990's to using non-radioactive Ytterbium, although some claim
that that the older Thorium mantles are both safe and more effective:
[http://www.colemancollectorsforum.com/post/peerless-
mantles-...](http://www.colemancollectorsforum.com/post/peerless-
mantles-5661914)

If you are excited by this but don't have a good source of dry ice (and are
electronically inclined) there is an interesting alternative design that uses
Peltier coolers and a PC power supply instead:
[http://www.instructables.com/id/Make-a-Cloud-Chamber-
using-P...](http://www.instructables.com/id/Make-a-Cloud-Chamber-using-
Peltier-Coolers/)

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dolzenko
Thanks, an amazingly beautiful demonstration which seems not very wide known.
Here is the video from "Harvard Natural Sciences Lecture Demonstrations" which
is quite beautiful (just the thing at work, without distractions)
[http://www.youtube.com/watch?v=e3fi6uyyrEs](http://www.youtube.com/watch?v=e3fi6uyyrEs)

~~~
ejr
That's very cool. Brian Cox did a variation on his programme with an added hot
water bottle on top :
[https://www.youtube.com/watch?v=fWxfliNAI3U](https://www.youtube.com/watch?v=fWxfliNAI3U)

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madaxe_again
I did this as a kid - serious fun. Used the americium from a smoke detector as
a source, after several abortive attempts to build a synchrotron... The third
time you wind several km of copper just to end up melting it is the last time,
it turns out - particularly after you explain to your parents what exactly it
is you're trying to do.

Either way, a small radioactive source is just great for some neat photos and
the occasional decay trace.

Leftovers from my melty mess went into a tesla coil, so not all was lost.

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decktech
Very pretty. I built a (less pretty) digital version a few years ago[0], based
on some really neat projects by this guy[1]

[0]: [http://kapamaki.net/muon-detector/](http://kapamaki.net/muon-detector/)
[1]: [http://www.hardhack.org.au/](http://www.hardhack.org.au/)

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alixaxel
I saw this for the first time in a Brian Cox show:

[http://youtu.be/fWxfliNAI3U](http://youtu.be/fWxfliNAI3U)

His suggestion that cosmic rays might have driven evolution is mind blowing!

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sanoli
Youtube has a bunch of nice videos of cloud chambers. Here's a good one:
[http://www.youtube.com/watch?v=SnKvtazt5So](http://www.youtube.com/watch?v=SnKvtazt5So)

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nolite
Saw my first one while visit Bridge at Caltech.. inspired me to build my own

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thisjepisje
I saw a cloud chamber in operation at a German university, very impressive.

