[en] We are reporting on a determination of neutral current coupling constants from a study of differential cross sections of muon-(anti)neutrino-electron scattering. The results were obtained with the CHARM-II detector which was exposed to the CERN wide band neutrino beam in the years 1987-1990. A total of about 2100 νe and 2200 anti νe scattering events were observed. From a comparison between the data and predicted event distributions, the effective vector and axial-vector neutral current coupling constants of the electron were determined to be g_V^e=-0.025±0.019 and g_A^e=-0.503±0.018. (orig.)

[en] We have measured the cross section for inverse muon decay in the CERN neutrino wide band beam. From 4808 events observed in the CHARM II detector we derived for the Born term of the asymptotic cross section slope the result (18.16±1.36)x10^-42 cm² GeV^-1. This cross section is in good agreement with the standard model prediction and allows to constrain the scalar coupling of the electron and muon to their neutrinos to vertical strokeg_LL^Svertical stroke²<0.405 at 90% CL. (orig.)

[en] We report on the first observation of neutrino induced production of muon pairs in the electromagnetic field of a nucleus. The data has been obtained using the CHARM II detector exposed to the CERN wideband neutrino and antineutrino beams. A clear signal of 55±16 events is seen in a sample of dimuons of opposite charge without visible recoil at the vertex. The cross section is determined and found to be in agreement with the standard model prediction. (orig.)

[en] The neutrino detector CHARM-II at CERN, consisting of a large target calorimeter equipped with streamer tubes and a muon spectrometer, has been exposed to a test beam of electrons, pions and muons with momenta between 2 and 60 GeV/c in order to study the digital response of the tubes, the analog response of the pickup strips and the momentum resolution of the muon spectrometer. Methods have been developed to carry the calibration results in space from the impact point of the test beam to the bulk of the detector and in time from the test period to all the data taking periods between 1987 and 1991. The number of hits along muon tracks was used to parametrize the dependence of fluctuations of temperature, tube voltage and gas composition. Curves and formulae are presented showing the energy response and the energy resolution for the different beam particles. The test beam data have been used to optimize and calibrate algorithms for the kinematical reconstruction of electron showers and for their extraction from the vast background of hadronic showers. (orig.)

[en] We are reporting on a new determination of sin²θ_W from the ratio of ν_μe to anti ν_μe scattering cross sections. A new detector designed for this purpose was exposed to the Wide Band Neutrino Beam of the 450 GeV CERN SPS. An analysis of data taken in 1987 and 1988 is presented based on 762 ν_μe and 1017 anti ν_μe events. From the ratio of σ(ν_μe) to σ(anti ν_μe) we determined sin²θ_W=0.233±0.012(stat)±0.008(syst) without radiative corrections. With radiative corrections for m_t=m_H=100 GeV we find sin²θ_W=0.232±0.012(stat)±0.008(syst). (orig.)

[en] We are reporting an improved determination of the electroweak mixing angle sin²Θ_w from the ratio of v_μe to ν_μe to ν_μe scattering cross sections. The CHARM II detector was exposed to neutrino and antineutrino wide band beams at the 450 GeV CERN SPS. Including new data collected in 1989 we have obtained 1316±56 ν_μe and 1453±62 anti ν_μe events. From the ratio of the visible cross sections we determined sin²Θ⁰=0.239±0.009 (stat)±0.007 (syst.) without radiative corrections and g_V^e/g_A^e=0.047±0.046. Combining this last result with recent results on g_A^e at LEP we obtain g_V^e=-0.023±0.023. (orig.)

[en] The CHARM II Collaboration has built a massive, fine-grained and low-density detector for the study of muon-neutrino and muon-antineutrino scattering on electrons. The detector consists of a target calorimeter of 692 t of glass followed by a magnetic spectrometer. The calorimeter is used to detect the different types of neutrino interactions, and to measure the energy and direction of the produced particle showers; the spectrometer permits the determination of the momentum of muons produced in charged-current reactions on nuclei. The calorimeter is composed of 441 detector planes having a total of 154560 plastic streamer tubes with digital readout of the wires and of 73920 cathode pickup strips grouped in 9240 channels with analog readout. It is further instrumented with 1540 scintillators. A complete description of the detector and some results of its performance with cosmic-ray muons are presented. (orig.)

[en] A search for ν_μ → ν_e and anti ν_μ → anti ν_e oscillations has been carried out with the CHARM II detector exposed to the CERN wide band neutrino beam. The data were collected over five years, alternating beams mainly composed of muon-neutrinos and muon-antineutrinos. The number of interactions of ν_e and anti ν_e observed is comparable with the number of events expected from flux calculations. For large squared mass differences the upper limits obtained on the mixing angle are sin²2θ < 9.4 . 10^-3 for ν_μ oscillating to ν_e and sin²2θ < 4.8 . 10^-3 for anti ν_μ to anti ν_e, at the 90% confidence level. Combining neutrino and antineutrino data the upper limit is 5.6 . 10^-3. (orig.)

[en] The final results from the CHARM II experiment on neutrino-electron scattering and inverse muon decay (IMD) are reported. From the study of the first process the vector and axial-vector coupling constants of the muon neutrino to the electron, g_V^νe, are obtained; the comparison of these results with the LEP measurements allows to test the Standard Model at a scale of Q² ∼0.01 GeV²,to estimate the coupling of the muon neutrino to the Z, and to test the universality of neutrino couplings in neutral current interactions. The study of the inverse muon decay reaction complements the results on muon decay in determining the structure of the charged current coupling of the electron to the muon; a limit on the scalar coupling of these particles is derived. (author). 5 figs., 9 refs

[en] We are reporting on a determination of neutral current coupling constants from a study of differential cross sections of muon-(anti)neutrino electron scattering. The results were obtained with the CHARM-II detector which was exposed to the CERN wide band neutrino beam in the years 1987 to 1991. A total of about 3000 νe and 3000 anti νe scattering events were observed. We present a preliminary value of sin² θ_W determined with the ratio of neutrino and antineutrino electron scattering cross-sections, based on the full data sample, and we give a determination of the effective vector and axial-vector neutral current coupling constants and the first measurement of the shape of the y-distributions based on 80% of the total statistics. (orig.)