The charged current nuclear transition C-12(nu(e), e-) N-12(g.s.) has been observed in the KARMEN experiment. The flux average cross section for nu(e) from mu+ decay at rest is determined to be [sigma] = [8.1 +/- 0.9(stat.) +/- 0.75(syst.)] x 10(-42) cm2. For the first time also the energy dependence of the cross section has been measured for neutrino energies up to 50 MeV.

The neutral current nuclear excitation 12(v,v′)12C∗ (1+, 1; 15.1 MeV) has been observed for the first time. For ve and vμ from μ+ -decay at rest the flux averaged cross section was determined to be <σNC(ve+vμ) > = [10.8±5.1 (stat.) ±1.1 (syst.)]×10−42 cm2.

KARMEN is a 56 t scintillation calorimeter designed for beam dump neutrino experiments at the neutron spallation facility ISIS of the Rutherford Appleton Laboratory. The calorimetric properties are demonstrated by cosmic muons and laser calibration. The measured energy resolution of the detector is σE/E ≈ 11.5%/√E[MeV], the position resolution σx = 5 cm and the timing resolution σt ≈ 350 ps.

The KARMEN experiment at the pulsed spallation neutron facility ISIS is investigating neutrino properties and interactions by measuring neutrino-induced charged current 12C(νρ,e−)12N and, for the first time, neutral current 12C(ν,ν′)12C∗ excitations of nuclei. Neutrino-nucleus interactions in the energy range up to 50 MeV are detected by a 56 ton high resolution liquid scintillation calorimeter with spectroscopic quality. Efficient background rejection results in clear neutrino signatures and allows reliable cross section measurements down to 10−42 cm2. After its first three years of data taking the experiment has identified and analysed more than 1000 neutrino-nucleus interactions. We present cross section results for neutrino-induced nuclear reactions with special emphasis on their implications for neutrino astrophysics, weak nuclear form factors and μ-e universality of neutral currents.