In reply to Jones Beene's message of Mon, 13 Jul 2015 18:34:11 -0700: Hi Jones, [snip] >-----Original Message----- >From: [email protected] > >> Note that a large part of the core of the Earth is hot, not cold, and also >subject to a small magnetic field, yet nevertheless absorbs few of the >neutrinos passing through it. > >On the contrary, Robin - the hot core of Earth could be considered evidence >of neutrino heating (or accelerated decay rates due to neutron flux). We do >not know the actual contribution of every source. We do know the amount of >neutrino flux at Earth' surface is astronomical, so to speak - around >7x10^10 neutrinos/cm^2/s ! Most of these would be non-solar in origin, but >that does not change the intensity which is actually higher inside than on >the surface.
The number generated by the Sun is about 6E10/cm^2/s, which is almost all of them (calculation available upon request). To determine the fraction that gets stopped by the Earth, you need to compare neutrino measurements taken during the day with those taken at night. (See http://www.theregister.co.uk/2014/03/17/earths_nightside_gets_different_kinds_of_neutrinos_from_dayside/) > >So-called "geo-neutrinos" which are generated in situ from beta decay, could >account for a portion of the internal heat - which could be in addition to >solar neutrinos. Each beta-decay releases a certain amount of energy, some fraction of which is in the form of neutrinos, the rest ends up as heat. Given that only an extremely small fraction of the neutrinos are absorbed, clearly they make no significant contribution. (See night-time/ day-time ratio). Given the article you quoted here below, the number of geo-neutrinos is about 10 thousand times less than the number of Solar neutrinos. (Rubbery calculation available upon request.) >At least the geo-neutrino is evidence of alpha/beta decay >QUOTE: Research has shown that Earth's total heat output is about 44 >terawatts...we found roughly half of that comes from radioactive decay of >uranium, thorium and other materials ... meaning that about 50 percent of >the earth's heat comes from geo-neutrinos." END This quote means that 50% of the energy comes from processes that *generate* geo-neutrinos, not from the energy of the geo-neutrinos themselves. (The experiment measured the anti-neutrino flux, to determine how many such reactions occurred. Based on the number of reactions, and the average energy contribution per reaction, they could then calculate the total contribution of such reactions to the heating of the planet.) > >That statement from the reference below is confusing, and indicates that >even the experts do not have much more than an informed guess. >At one time, >not too long ago - this internal heat was said to come from uranium fission >- now fission is said to be all but non-existent (compared to decay). And >furthermore - we know that beta decay itself is influenced by background >neutrino flux. > http://www.astrobio.net/topic/solar-system/earth/geology/half-of-earths-heat -from-radioactive-decay/#sthash.PQXjYiwj.dpuf Regards, Robin van Spaandonk http://rvanspaa.freehostia.com/project.html
