How Do You Catch an Atom?

One of the many documentaries we have watched lately was this one....  Project Poltergeist.  It talks about the discovery of the neutrino. I admit... I didn't really know what a neutrino was before I saw this, and even after watching it, I feel like my brain is stretching and pushing against my eye balls trying to grasp some of the concepts. A little like quantum theory really!  But anyway.... it was amazing watching what these scientists were doing.   Basically, a mathematician had calculated the number of neutrinos that should be coming from the sun, and the physicists were trying to prove that was so. The problem was, when they counted them... the numbers didn't add up. The 'Solar Neutrino Problem' was born.

The thing was.... the documentary glossed over the bit that I wanted to know the most.  Perhaps it wasn't interesting to other people - but see what you think.  A giant swimming pool sized vat of chlorine-based cleaning fluid deep deep under ground to lessen the background radiation. The neutrinos pass right through the planet, and just a few of them should interact with the cleaning fluid, causing the creation of an Argon atom.  So even though they couldn't see the neutrinos - they could see the result of them as proven by the Argon.  Collect and count the Argon atoms and you can tell how many neutrinos you have... voila!       Huh?  What....  'scuse me?

They just breezed past that.  Suddenly there was Ray Davis (who was to go on and win the Nobel Prize for this astounding work)... carrying a test tube.. with... *what* in it?   his wife was joking about how he would travel across the country with a little tube full of nothing.  But... but....  hang on.  How do they catch an atom.. how do they count it? How did they know they only had a measly three?  That was a huge amount of liquid... this is not like looking for a pea or something.  From everything I have seen and read, I didn't think we had a way to see atoms or measure them... so this is huge to me. I really want to know.  I can't seem to find it on google.

So they went on to discover that the neutrinos didn't quite travel at light speed and actually have a mass (both of which they didn't expect), which enabled them to change their state on their way to earth and in fact show up as 3 different flavours of neutrino - all this good and groovy stuff... but I am still hung up on how the frak do you find and count a few atoms in a swimming pool?  If anyone reads this and knows... please comment. I am eagerly waiting....



2/13/10, 1:01 PM

This page has a lot of info on neutrinos. Apparently one detects argon atoms as they decay naturally back into chlorine. The decay is paired with a release of energy in the form of a particular X-ray which is detectable.

But hey, I'm no physicist.



2/13/10, 8:29 PM

OK.. interesting. They didn't show anything involving xrays with Ray Davis - just pouring liquids around in test tubes and chilled bottles, so I think it was highly glossed over. The fact that they intimated he 'carried' little tubes of atoms around made it sound like he had isolated them in some way. What you're saying would sound more plausible for sure... but I still want to know more :)


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