2021-10-18 "Diagnostic Potential

D. The Absorption Cross Section

Nucleons are so rare throughout the Universe at large (nB = (2.5 ± 0.1) × 10−7 cm−3 in the current Universe [3]) that neutrino–nucleon scattering is a negligible source of attenuation, even over cosmological distances. A path length of 8 × 105 Mpc in today’s Universe corresponds to 1 cm water equivalent (cmwe).

[a]

Reference:

[a]. https://arxiv.org/abs/hep-ph/0412122 .
Diagnostic Potential of Cosmic-Neutrino Absorption Spectroscopy
Gabriela Barenboim,Olga Mena Requejo,Chris Quigg

 [3] S. Eidelman et al. [Particle Data Group], Phys. Lett. B

592, 1 (2004).

以上。