%A"Kleifges, M" %D1994 %I; Kernforschungszentrum Karlsruhe GmbH (Germany). Inst. fuer Kernphysik; Karlsruhe Univ. (T.H.) (Germany). Fakultaet fuer Physik %2 %J[] %K73 NUCLEAR PHYSICS AND RADIATION PHYSICS, 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS, MUONS PLUS, LEPTONIC DECAY, NEUTRINO REACTIONS, CHARGE-EXCHANGE REACTIONS, CARBON 12 TARGET, INTEGRAL CROSS SECTIONS, MEV RANGE 10-100, ENERGY SPECTRA, CHARGED-CURRENT INTERACTIONS, ELECTRONS, NITROGEN 12, GROUND STATES, EXPERIMENTAL DATA, ELECTRON SPECTRA, ENERGY DEPENDENCE, EXCITATION FUNCTIONS, DIFFERENTIAL CROSS SECTIONS, ANGULAR DISTRIBUTION, 663420, 663520, 662370, LEPTON-INDUCED REACTIONS AND SCATTERING, A = 6-19, DECAYS OF LEPTONS %PMedium: X; Size: 102 p. %TFirst measurement of the energy spectrum of electron neutrinos from {mu}{sup +}-decay; Erste Messung des Energiespektrums von Elektronneutrinos aus dem {mu}{sup +}-Zerfall %XThe neutrino experiment KARMEN has been performing measurements for more than 4 years at the spallation source ISIS at the Rutherford-Appleton-Laboratory in Great Britain. In the experiment the neutrinos {nu}{sub {mu}}, {nu}{sub e} and anti {nu}{sub {mu}} from the pion decay chain in the ISIS target are detected in a 56t-liquid scintillator calorimeter. Besides the search for neutrino oscillation in the chanel {nu}{sub {mu}}{yields}{nu}{sub e} and anti {nu}{sub {mu}}{yields} anti {nu}{sub e} the other main physics aim is the investigation of the neutrino-nucleus interaction by neutral and charged weak currents. This report concentrates on the exclusive nuclear excitation by the charged current {nu}{sub e}+{sup 12}C{yields}{sup 12}N{sub g.s.}+e{sup -}. Due to the sequential signature as a result of {sup 12}N-decay this reaction allows an investigation with high signal to background ratio 34:1. The analysis of the data since June 1990 yields 291 events of which 8.3 were assigned to background events. Hence the flux averaged cross section of the exclusive nuclear excitation in the energy range 0-53 MeV was measured to be left angle {sigma} right angle {sub cc}=[9.1{+-}0.55(stat.){+-}0.74(syst.)]x10{sup -42} cm{sup 2} which is in good agreement with theoretical calculations. Besides this result, the good calorimetric properties of the KARMEN detector make it possible to unfold the primary energy of the detected electrons. This unfolding enabled both the energy dependent cross section and the energy distribution of the electron neutrinos from unpolarized {mu}{sup +}-decay to be determined. The measurement of the {nu}{sub e}-energy spectrum from the {mu}{sup +}-decay offers a totally new and highly sensitive possibility for the study of the Lorentz structure of this weak decay. The influence of possible scalar and tensor coupling components, that could give a hint on physics beyond the standard model, is described by the {nu}{sub e}-Michel parameter {omega}{sub L}. %0Thesis/Dissertation %NKFK-5394;Journal ID: ISSN 0303-4003; Other: ON: DE95731723; TRN: DE94FO222 %1 %CGermany %Rhttps://doi.org/ Journal ID: ISSN 0303-4003; Other: ON: DE95731723; TRN: DE94FO222 DEN %GGerman