Setup of a Drift Tube Muon Tracker and Calibration of Muon ...

Figure 2.1: Neutrino flux at Earth predicted by the Standard Solar Model. Solidlines: neutrinos produced in the pp-chain, dashed lines: neutrinos produced in theCNO cycle. Figure taken from [43]. For neutrinos with a continuous energy spectrum,the flux is given per MeV bin.measurements can therefore be used to test the prediction of the SSM that the Sunis in a quasi-steady state in which the energy rate released in the fusion processesequals the surface radiation rate.2.3.3 Oscillations of Solar NeutrinosDetermining parameters of solar oscillation allows to improve the measurements of∆m 12 and θ 12 . Especially the MSW effect presented in Section 2.2.2 offers a largephysics potential regarding solar neutrinos. Solar neutrino oscillations would benegligible without matter enhancement. Solar ν e s are mixtures of ν 1 and ν 2 witha negligible component of ν 3 . It is thus possible to regard their propagation as atwo neutrino phenomenon with the two flavor states ν e and ν x , the latter beinga combination 8 of ν µ and ν τ . From Eq. 2.7 one can see, that the matter effectson a neutrino’s oscillation grows with the particle’s energy. In the solar neutrinospectrum, the 8 B neutrinos have (next to hep neutrinos) the highest energy, so theinfluence of the Sun’s matter should be most significant for them. Assuming, solarneutrinos are created in the Sun’s core, the particle travels through regions withadiabatic decreasing electron densities N e on its way to Earth. N e reduces slowly onthe way outside the Sun, leading to a radius r dependent potential V W . It can beshown that due to the MSW effect, a 8 B ν e produced in the core as a superposition8 The exact ν µ ν τ composition depends on the atmospheric mixing angle θ atm and is of noimportance here13