A. Baldini

Limits on neutrino oscillations from the CHOOZ experiment

Abstract We present new results based on the entire CHOOZ (The CHOOZ experiment is named after the new nuclear power station operated by Electricite de France (EdF) near the village of Chooz in the Ardennes region of France) data sample. We find (at 90% confidence level) no evidence for neutrino oscillations in the ν e disappearance mode, for the parameter region given by approximately δm 2 >7·10 −4 eV 2 for maximum mixing, and sin22θ=0.10 for large δm2. Lower sensitivity results, based only on the comparison of the positron spectra from the two different-distance nuclear reactors, are also presented; these are independent of the absolute normalization of the ν e flux, the cross section, the number of target protons and the detector efficiencies.

Search for neutrino oscillations on a long base-line at the CHOOZ nuclear power station

Abstract. This final article about the CHOOZ experiment presents a complete description of the

Initial results from the CHOOZ long baseline reactor neutrino oscillation experiment

bar{nu}_e

Measurement of the neutron and proton structure functions from neutrino and antineutrino scattering in deuterium

source and detector, the calibration methods and stability checks, the event reconstruction procedures and the Monte Carlo simulation. The data analysis, systematic effects and the methods used to reach our conclusions are fully discussed. Some new remarks are presented on the deduction of the confidence limits and on the correct treatment of systematic errors.

Determination of neutrino incoming direction in the CHOOZ experiment and supernova explosion location by scintillator detectors

Abstract Initial results are presented from CHOOZ 1 , a long-baseline reactor-neutrino vacuum-oscillation experiment. The data reported here were taken during the period March to October 1997, when the two reactors ran at combined power levels varying from zero to values approaching their full rated power of 8.5 GW (thermal). Electron antineutrinos from the reactors were detected by a liquid scintillation calorimeter located at a distance of about 1 km . The detector was constructed in a tunnel protected from cosmic rays by a 300 MWE rock overburden. This massive shielding strongly reduced potentially troublesome backgrounds due to cosmic-ray muons, leading to a background rate of about one event per day, more than an order of magnitude smaller than the observed neutrino signal. From the statistical agreement between detected and expected neutrino event rates, we find (at 90% confidence level) no evidence for neutrino oscillations in the ν e disappearance mode for the parameter region given approximately by Δm 2 >0.9 10 −3 eV 2 for maximum mixing and sin22θ>0.18 for large Δm2.Initial results are presented from CHOOZ , a long-baseline reactor-neutrino vacuum-oscillation experiment. The data reported here were taken during the period March to October 1997, when the two reactors ran at combined power levels Ž . varying from zero to values approaching their full rated power of 8.5 GW thermal . Electron antineutrinos from the reactors were detected by a liquid scintillation calorimeter located at a distance of about 1 km. The detector was constructed in a tunnel protected from cosmic rays by a 300 MWE rock overburden. This massive shielding strongly reduced potentially troublesome backgrounds due to cosmic-ray muons, leading to a background rate of about one event per day, more than an order of magnitude smaller than the observed neutrino signal. From the statistical agreement between detected and expected Ž . neutrino event rates, we find at 90% confidence level no evidence for neutrino oscillations in the n disappearance mode e 1 ́ Ž . The CHOOZ experiment is named after the new nuclear power station operated by Electricite de France EdF near the village of Chooz ́ in the Ardennes region of France. 0370-2693r98r

Investigation of exclusive channels in ν/ν-deuteron charged current interactions

19.00 q 1998 Elsevier Science B.V. All rights reserved. Ž . PII S0370-2693 97 01476-7 ( ) M. Apollonio et al.rPhysics Letters B 42

New experimental limits on νμ→νe oscillations

Abstract Data from an exposure of the BEBC bubble chamber filled with deuterium to neutrino and antineutrino wide band beams have been used to extract the x dependence of the structure functions for scattering on protons and neutrons and the fractional momentum distributions of the valence quarks and the antiquarks of different flavours. The difference F n 2 − F p 2 is compared with recent data from high energy μD scattering. A result is also obtained on the sum rule giving the difference between the number of up and down quarks in the nucleon.

INCLUSIVE rho0 PRODUCTION IN anti-muon-neutrino D AND muon-neutrino D CHARGED CURRENT INTERACTIONS.

The CHOOZ experiment measured the antineutrino flux at a distance of about 1 Km from two nuclear reactors in order to detect possible neutrino oscillations with squared mass differences as low as 10**-3 eV**2 for full mixing. We show that the data analysis of the electron antineutrino events, collected by our liquid scintillation detector, locates the antineutrino source within a cone of half-aperture of about 18 degrees at the 68% C.L.. We discuss the implications of this experimental result for tracking down a supernova explosion.

Fragmentation in neutrino and antineutrino charged current interactions on proton and neutron

Abstract An analysis has been performed of neutrino and antineutrino interactions with protons and neutrons in a deuterium bubble chamber. The interactions under study are quasielastic neutrino-neutron scattering and one-, two- and three-pion production reactions. Results are presented on cross sections, effective mass distributions, resonance production, momentum transfer distributions and coefficients of the decay angular distributions. Where possible, comparisons are made with existing theoretical models and predictions.

Measurement of the νμ and νμ nucleon charged-current total cross sections, and the ratio of νμ neutron to νμ proton charged-current total cross sections

Abstract The results of an experiment which searched for ν e events arising from oscillations of a low-energy ν μ beam are presented. The BEBC heavy liquid bubble chamber, placed at a distance of 825 m from an external proton target at the CERN PS, was used as a neutrino detector. The appearance of ν e CC interactions provides a sensitive indication of ν μ → ν e oscillations. 470 ν μ CC events and 4 ν e events, with an estimated background of 3 ν c CC events, have been observed. The resulting limits on the oscillation parameters are: δm 2 ⩽0.09 eV 2 (for maximal mixing) and sin 2 θ ⩽0.013 for δm 2 =2.2 eV 2 , at the 90% confidence level.