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Re: [Phys-L] Where are all the slow neutrinos?



On 07/08/2016 02:48 PM, Derek McKenzie asked:

why do we perpetuate this misconception of there being such a thing
as 'close to the speed of light'?

It's like a 55 mph speed limit. The speed is, by convention, relative
to the local terrestrial frame.

Where are all the slow neutrinos?

Two answers:
-- If you had a fast neutrino, it would be hard to slow it down, because
of the small cross-section.
-- If you had a slow neutrino, you would never be able to see it. Seeing
the fast ones takes heroic efforts, and the cross section goes down
even more as the energy goes down.

Searching for
https://www.google.com/search?q=neutrino+%22inverse+beta%22+%22cross+section%22+energy

immediately turns up
J.A. Formaggio, G.P. Zeller
"From eV to EeV: Neutrino Cross Sections Across Energy Scales"
https://arxiv.org/pdf/1305.7513v1.pdf

which will tell you what you wanted to know.