Home Astronomy Neutrinos – present in vast numbers but barely interact with matter

Neutrinos – present in vast numbers but barely interact with matter

by Granite

The sun emits vast numbers of neutrinos which can pass through the earth with little or no interaction. Solar neutrinos shine down on us during the day, and shine up on us during the night after passing through the earth almost no absorption. About 91% of solar neutrons are produced by the proton-proton fusion to produce deuterium.  Neutrinos from the proton-proton fusion have low energy up to 400 keV.  The flux of low energy neutrons is about 7 x 1010  neutrinos/cm2s, i.e 70 billion neutrinos per square cm per second.  A square centimetre is about the size of your small finger nail.  There are several other processes producing neutrinos up to 18 MeV (see figures below).

Neutrinos detected by the University of Tokyo’s underground Kamiokande experiment from the supernova SN 1987A in the Magellan cloud galaxy.

Ten neutrino events were detected in a deep mine neutrino detection facility in Japan which coincided with the observation of Supernova 1987A. They were detected within a time interval of about 15 seconds against a background of lower energy neutrino events. A similar facility, IMB in Ohio detected 8 neutrino events in 6 seconds. These observations were made 18 hours before the first optical sighting of the supernova.  http://hyperphysics.phy-astr.gsu.edu/hbase/Astro/sn87a.html#c2


Solar neutrino flux

Solar neutrino flux at earth from different reactions in the sun. https://www.wikiwand.com/en/Solar_neutrino#cite_note-Bellerive2004-14


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