Finding the Neutrino


The method of detecting a Neutrino is similar to detecting its counterpart. The fusion of four hydrogen nuclei produces two neutrinos with every helium nucleus. While it is not practical to set off a thermo-nuclear weapon simply to try and detect neutrinos there is a very large, constant, and obvious source of neutrinos that is easily at the disposal of Physicists. That great neutrino producer is the Sun (or any star). The method of detecting neutrinos uses a reaction this is similar to the reaction to detect antineutrinos. In an antineutrino detection reaction an antineutrino collides with a proton to produce a neutron and a positron while in a neutrino detection reaction a neutrino collides with a neutron to produce a proton and an electron.

The chemical detector of choice is perchloroethylene, a molecule of two carbons and four chlorines. The chlorines are important because chlorine-37 has twenty neutrons and if one were to react it would produce argon-37, a gas that is radioactive and therefore easily detected. This chemical is stored deep in the earth, about a mile, so that they are protected from all other external radiation (including cosmic rays). These experiments have detected solar neutrinos but only about 1/3 of what was expected.(Asimov 238)

As recently as this year major discoveries have been made in the area of neutrinos. It has been announced recently that the reason that all of the solar neutrino experiments have seemed to have too few electron neutrinos is that it is now believed that neutrinos can change type. In addition, it has been announced that the neutrino is no longer believed to be mass less but with a very slight mass, one hundred and eighty thousandth the mass of an electron. (Scientific American)

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