C. Oehler

Measurement of the weak neutral current excitation 12C(νμνμ′)12C∗(1+,1;15.1MeV) at Eνμ=29.8 MeV

Abstract The weak neutral current reaction 12 C( ν μ , ν μ ′ ) 12 C ∗ (1 + ,1; 15.1MeV) has been observed for the first time in the KARMEN experiment. Neutrino events were separated from background using two different analysis methods. The measured cross section σ NC =(3.2 ± 0.5 stat. ± 0.4 syst. ) × 10 −42 cm 2 for monoenergetic ν μ from π + -decay at rest is in good agreement with the standard model, the isovector-axialvector coupling constant of weak hadronic current deduced from this experiment is | β |=1.11±0.13.

Neutrino oscillation results from KARMEN

The neutrino experiment KARMEN is situated at the beam stop neutrino source ISIS. It provides νμs, νes and νμs in equal intensities from the π+-μ+-decay at rest (DAR). The oscillation channels νμ → νe and νμ → νe are investigated in the appearance mode with a 56t liquid scintillation calorimeter at a mean distance of 17.7m from the ν-source. Analyses of experimental data from the measuring period 1990–1995 corresponding to 9122 C protons on target or 2.52 · 1021μ+ DAR are presented. No evidence for oscillations could be found with KARMEN, resulting in 90% CL exclusion limits of sin2(2θ) < 8.5·10−3 (νμ → νe) and sin2(2θ) < 4.0·10−2 (νμ → νe) for Δm2 ≥ 100 eV2 in a simple 2 flavor description of ν-oscillations.

KARMEN at ISIS: The advantage of a pulsed neutrino source in the search for neutrino oscillations and neutrino nuclear interactions

Abstract KARMEN, the Karlsruhe-Rutherford Medium Energy Neutrinoexperiment at the pulsed spallation neutron facility ISIS uses the beam stop neutrinos νμ, νe and ν μ from π+ and μ+ decay at rest to search for neutrino oscillations in the appearance channels νμ → νe and ν μ → ν e. The signature for both oscillations is based on charged current neutrino nuclear interaction spectroscopy in a high resolution 56 t liquid scintillator calorimeter. The detector system has been upgraded with an additional veto layer during 1996 to eliminate cosmogenic background and to enhance its sensitivity in the oscillation channels. This report describes the results based on data acquired from June 1990 to August 1995 and the first data of 1997 with the new veto system in operation.

KARMEN-Upgrade: Status and first results

KARMEN, the Karlsruhe-Rutherford Medium Energy Neutrinoexperiment at the pulsed spallation neutron facility ISIS uses the beam stop neutrinos νμ, νe and νμ from π+ and μ+ decay at rest to search for neutrino oscillations in the appearance channels νμ → νe and νμ → νe. The signature for both oscillations is based on charged current neutrino nuclear interaction spectroscopy in a high resolution 56 t liquid scintillator calorimeter. The detector system has been upgraded with an additional veto layer during 1996 to eliminate cosmogenic background. This report describes results for the oscillation channel νμ → νe based on data acquired from June 1990 to August 1995 and the first data of 1997 with the new veto system in operation.