KARMEN νe → νx disappearance search in a 3 neutrino flavor analysis

Abstract

The 56 ton scintillation calorimeter KARMEN at the beam stop neutrino source ISIS has been used to search for neutrino oscillations in the disappearance channel ν e → ν x . The ν e emitted in μ + decay at rest (DAR) are detected with spectroscopic quality via the exclusive charged current (CC) reaction 12C(ν e,e −) 12N g.s. . Analysis of the spectral shape of e − from the ν e induced reaction as well as a measurement of the absolute ν e flux allow to investigate oscillations of the type ν e → ν τ and ν e → ν μ . The flux independent ratio R CC/ NC of CC events 12C(ν e,e −) 12N g.s. to NC events 12C(ν,ν′) 12C ∗ provides additional information. All three methods show no evidence for oscillations. A complete 3 flavor analysis of the experimental data with respect to ν e ↔ ν τ and ν e ↔ ν μ mixing is presented.