How to Detect Solar Neutrinos

In memory of Raymond Davis, Jr.
[Oct 14, 1914-May 31, 2006]

A mile down the Homestake Mine,
delve for riches rarer than gold.

In darkness, in the hot depths,
search for evidence, a sign:

chlorine transforming to argon
in the alchemy of neutrinos.

Insubstantial, invisible,
unveiled by their actions.

Messengers born in brightness,
forged in the Sun’s fire.

— Mary Soon Lee


Mary Soon Lee was born and raised in London, but now lives in Pittsburgh. She writes both fiction and poetry, and has won the Rhysling Award and the Elgin Award. Her book Elemental Haiku, containing haiku for each element of the periodic table, will be published by Ten Speed Press in October 2019. Her poetry has appeared in Analog, Asimov’s, F&SF, Science, and Strange Horizons. She has an antiquated website at and tweets at @MarySoonLee

Editor’s Notes: An experiment headed by astrophysicists Raymond Davis, Jr. and John N. Bahcall in the late 1960s at the Homestake Gold Mine in Lead, South Dakota, successfully collected and counted solar neutrinos emitted by nuclear fusion the Sun’s core using a 100,000 gallon tank of perchloroethylene (a dry-cleaning liquid) 4,850 feet underground to shield from cosmic neutrinos. Chlorine-37 interacts with a solar neutrino of the right energy and transforms into a radioactive argon-37 atom, which is extracted and counted. Davis’s detector was sensitive to only one type of neutrino; it was unknown at the time, but later discovered that neutrinos could change their flavor (a quantum mechanical state) via neutrino oscillations. Davis shared the 2002 Nobel Prize in Physics with Masatoshi Koshiba of Japan and Riccardo Giacconi of the US.

The graph of the (long range) electron neutrino oscillations is superimposed on a colorful image of the sun ( The three flavors are that of an electron neutrino (black), a muon neutrino (blue) and a tau neutrino (red).

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