Chlorine-37 - Wikipedia

Isotope of chlorine Chlorine-37

General
Symbol	37Cl
Names	chlorine-37
Protons (Z)	17
Neutrons (N)	20
Nuclide data
Natural abundance	24.22%[1]
Isotope mass	36.965903[2] Da
Isotopes of chlorine Complete table of nuclides

Chlorine-37 (37Cl), is one of the stable isotopes of chlorine, the other being chlorine-35 (35Cl). 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 35.45 g/mol.[3]

Remarkably, solar neutrinos were discovered by an experiment (Homestake Experiment) using a radiochemical method based on chlorine-37 transmutation.[4]

Neutrino detection

[edit] Main article: Homestake experiment

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.[5] Chlorine-37 transmutes into argon-37 via the reaction[6]

37Cl + νe → 37Ar + e−.

Argon-37 then decays via electron capture (half-life 35.01 days) into chlorine-37 via the reaction

37Ar + e− → 37Cl + νe.

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.[4][5][7]

See also

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• Beta decay
• Neutrino detection
• Isotopic tracer
• Isotopes of chlorine

References

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1. ^ "Standard Atomic Weights: Chlorine". CIAAW. 2009.
2. ^ Wang, Meng; Huang, W.J.; Kondev, F.G.; Audi, G.; Naimi, S. (2021). "The AME 2020 atomic mass evaluation (II). Tables, graphs and references*". Chinese Physics C. 45 (3) 030003. doi:10.1088/1674-1137/abddaf.
3. ^ Prohaska, Thomas; et al. (2022-05-25). "Standard atomic weights of the elements 2021 (IUPAC Technical Report)". Pure and Applied Chemistry. 94 (5): 573–600. doi:10.1515/pac-2019-0603.
4. ^ a b J.N. Bahcall (1969). "Neutrinos from the Sun". Scientific American. 221 (1): 28–37. Bibcode:1969SciAm.221a..28B. doi:10.1038/scientificamerican0769-28.
5. ^ a b Sutton, Christine (1992). Spaceship Neutrino. Cambridge University Press. pp. 151–152. ISBN 978-0-521-36404-1. OCLC 25246163. chlorine-37 neutrino.
6. ^ F.H. Shu (1982). The Physical Universe: An Introduction to Astronomy. University Science Books. p. 122. ISBN 978-0-935702-05-7. chlorine 37 neutrino.
7. ^ A. Bhatnagar, W. Livingston (2005). Fundamental of Solar Astronomy. World Scientific. pp. 87–89. ISBN 978-981-238-244-3.