Neutrinos and the supernova origin of the elements

Intense fluxes of neutrinos are emitted by the hot neutron star produced in a supernova. The average supernova neutrino energies satisfy a robust hierarchy.(E_νe) < (E_νe) < (E_νμ(τ)) ≈ (E_νμ(τ)). The v_e and v̄_e capture rections on neutrons and protons, respectively, provide heating to drive a wind from the hot neutron star. The same reactions also determine the neutron-richness of the wind material. Nucleosynthesis via rapid neutron capture, the r-process, may occur in the wind material as it expands away from the neutron star. The neutron-richness of the wind material, and hence, the r-process nucleosynthesis therein, are sensitive to mixing between ν_μ(τ)/ν̄_μ(τ) and ν_e/ν̄_e (or sterile neutrinos ν_s/ν̄_s) at the level of sin² 2θ ≲ 10^-4 for δm² ≳ 1 eV². Indirect arguments and direct tests for the supernova origin of the r-process elements are discussed with a goal to establish supernova r-process nucleosynthesis as an important probe for neutrino mixing.