Expected signals in relic neutrino detectors

Abstract

Here we estimate the magnitude of the signals expected for realistic cosmic neutrino backgrounds in detectors attempting to measure the mechanical forces exerted on macroscopic targets by the elastic scattering of relic neutrinos. We study effects proportional to the weak coupling constant G F and to G F 2 for Dirac and Majorana neutrinos, either relativistic or nonrelativistic, both gravitationally bound or not.

How difficult it would be to detect cosmic neutrino background?

“…More recent analysis of the acceleration due to both the effects proportional to G F and G 2 F was performed in Ref. [13], with the same conclusion, namely that with the present technology such detection is essentially impossible.…”

Prospect for Relic Neutrino Searches

“…The general expression for the energy of one electron in the CνB, in the electron-rest frame, to first order in β earth , both for Dirac and Majorana neutrinos were first derived in Ref. [19]. Let us see the most relevant particular cases, starting from early times, before the decoupling of neutrinos.…”

“…The effect, originally derived by Stodolski [24] only for Dirac neutrinos, is proportional to the product σ e · β e (n ν − nν). For Majorana neutrinos (for which ν =ν), only the γ µ γ 5 term remains, and [νγ µ γ 5 ν] yield in the non-relativistic limitν( σ ν · β ν , σ ν )ν ∼ (n ν ℓ − n νr ), which is non-zero only if there is a net helicity in the CνB [19].…”

“…A possible solution would be a concentric balance [28]. Solar neutrinos would produce equal or larger accelerations (and possibly dark matter particles could too) [19]. So directionality would be needed to separate a signal from relic neutrinos (Smith and Lewin [27] proposed using laminated materials).…”

“…For non-clustered non-relativistic Dirac neutrinos (i.e for most relic neutrinos), the cross-sections are [19] …”