Direct detection (even subtly) of the Cosmic Neutrino Background?

[repoman]

Cool stuff, way beyond my skill set to even have much of an understanding of, but worth a thread I would say.

https://en.wikipedia.org/wiki/Cosmic_neutrino_background#Prospects_for_the_direct_detection_of_the_C%CE%BDB

http://www.int.washington.edu/talks/WorkShops/int_10_44W/People/Formaggio_J/Formaggio.pdf

there is a messed up slide that is this:

 

[lpetrich]

Let's see how fast tritium decays: T -> He3 + e + nu

100 grams = 33 moles = 2.00*10^(25) atoms.

Half-life = 12.32 years, mean life = 17.77 years.

Decay rate = 1.12*10^(24) per year.

Energy released = 18.6 keV.

Expected primordial-neutrino reaction: T + nu -> He3 + e

Expected primordial-neutrino energy: around 1 meV, about 1/(2*10^7) of the maximum decay energy. So it may be hard to observe electrons with 1 meV more than the maximum. However, the number at each energy is determined by the amount of phase space, how many momenta available. For E to Emax for the electrons, the neutrinos don't have much energy, and we get something proportional to (Emax-E)^3. That gives us roughly 100 electrons per year. So one may be able to observe these primordial neutrinos if one can measure electron energies with sufficient precision.