Hey Steemers,
The following is a quick description of the neutrino (an unusual subatomic particle), along with a look at the Sudbury Neutrino Observatory (one of the most interesting facilities I've ever come across.
A neutrino is a tiny particle with less mass than any other known particle (they're less than a millionth the size of an electron). They're unique in that they do not really interact with the physical world - usually, they pass right through matter without so much as bumping into a single atom. This is a very good thing, since trillions of neutrinos (cast off by the sun's radioactive decay) pass through all of our bodies every single day.
Because these particles are so light, and because they really don't interact with matter, it was extremely difficult to prove their existence. An Austrian physicist named Wolfgang Pauli first theorized the neutrino's existence in the 1930s. Several other physicists actually detected the particles in 1942 (using beta capture, which I won't go into).
This brings me to what I really want to talk about - the Sudbury Observatory. This is a facility located two kilometers underground, in an abandoned nickel mine in Canada. Here's the layout of the mine:
The Observatory consists of an 20-foot diameter spherical tank of heavy water (deuterium) with extremely sensitive detectors positioned all around the tank. Here's a pic:
Here's a diagram that gives some context:
Here's how it works: Although neutrinos almost rarely react with matter, one in several trillion will react with a deuterium molecule - turning one of the neutrons of the molecule into a proton. Normally, there would be too much other radiation affecting the heavy water in the tank for anybody to observe neutrino activity. This is why it's located in a mine - the 2 kilometers of solid rock shield the tank from any other particles being cast off by the sun. However, because neutrinos don't really react with matter, they get through.
The spherical tank of heavy water is housed in a clean room environment (fewer than 3000 particles per cubic foot), and is bolted to the ceiling of the mine with high performance bolts.
The Director of the neutrino experiment at the Sudbury Neutrino Observatory won a Nobel prize for his work. Here he is:
