Neutrino physics: experiments The dark side of the Universe, ISAPP, MPIK Heidelberg, May 29/30, 2019 ν νe µ Christian Weinheimer Institut für Kernphysik, Westfälische Wilhelms-Universität Münster
[email protected] ν τ A reminder: Neutrinos in the Standard Model of Particle Physics Prof. Dr. Takaaki Kajita Neutrino oscillations: experiments with atmospheric, solar, accelerator and reactor neutrinos Neutrino masses: - cosmology and astrophysics - neutrinoless double β decay - direct neutrino mass experiments Search for sterile neutrinos Coherent neutrino nucleus elastic scattering Prof. Dr. Arthur B. McDonald Christian Weinheimer ISAPP Heidelberg May 29/30, 2019 1 Experimental proof n of neutrinos ν e p e+ 1956: Cowan and Reines: Poltergeist experiment strong νe source: nuclear power reactor: 6 fission (from fission products), E 9 MeV νe ν energy gain / fission: 200 MeV 1 GW thermal power 2 1020 ν/s + Detection reaction: inverse β decay: νe + p n + e (threshold: 1.8 MeV) Signature:a) n: thermalisation by elastic scattering, capture on Cd γ 's b) e+: annihilation 2 γ 's (511 keV) spatial and time-delayed coincidence (nearly background free) measured cross section: (1.1 ± 0.3) 10-43 cm2 figure: Schmitz: Neutrinophysics, Teubner (in good agreement with Fermi`s theory for V-A) Christian Weinheimer ISAPP Heidelberg May 29/30, 2019 2 ν's in the electroweak Standard Model: U(1)SU(2) 12 fundamental fermions 6 left-handed weak isospin dublets: pure weak isospin dublets weak S. Glashow isospin dublets 9 right-handed weak isospin singulets: (no νR in SM) massive leptons in charged S. Weinberg weak currents (CC): - lepton: For masseless particles (ν in SM): P(H = 1) = (1 -v/c))/2 P = -v/c σ Long c ΨL , ΨR have helicity H = -1 p - anti lepton: P(H = 1) = (1 v/c)/2 σ P = v/c A.