Chlorine-37 (), is one of the stable isotopes of chlorine, the other being chlorine-35 (). Its nucleus contains 17 protons and 20 neutrons for a total of 37 nucleons. Chlorine-37 accounts for 24.22% of natural chlorine, with chlorine-35 the remaining 75.78%, giving chlorine in bulk an apparent atomic weight of .
Remarkably, solar neutrinos were discovered by an experiment (Homestake Experiment) using a radiochemical method based on chlorine-37 transmutation.
Neutrino detection
One of the historically important radiochemical methods of solar neutrino detection is based on inverse electron capture triggered by the absorption of an electron neutrino. Chlorine-37 transmutes into argon-37 via the reaction + → + .
Argon-37 then decays via electron capture (half-life 35.01 days) into chlorine-37 via the reaction + → + .
The detection of these electrons confirms that a neutrino event occurred. Detection methods involve several hundred thousand liters of carbon tetrachloride (CCl4) or tetrachloroethylene (C2Cl4) stored in underground tanks.
See also Beta decay Neutrino detection Isotopic tracer Isotopes of chlorine
References