Initial Results from the CHOOZ Long Baseline Reactor Neutrino Oscillation Experiment

Initial results are presented from CHOOZ, a long-baseline reactor-neutrino vacuum-oscillation experiment. Electron antineutrinos 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 electron antineutrino disappearance mode for the parameter region given approximately by deltam**2 > 0.9 10**(-3) eV**2 for maximum mixing and (sin(2 theta)**2) > 0.18 for large deltam**2.Comment: 13 pages, Latex, submitted to Physics Letters

Limits on Neutrino Oscillations from the CHOOZ Experiment

We present new results based on the entire CHOOZ data sample. We find (at 90% confidence level) no evidence for neutrino oscillations in the anti_nue disappearance mode, for the parameter region given by approximately Delta m**2 > 7 x 10**-4 eV^2 for maximum mixing, and sin**2(2 theta) = 0.10 for large Delta m**2. 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 anti_nue flux, the cross section, the number of target protons and the detector efficiencies.Comment: 19 pages, 11 figures, Latex fil

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

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.Comment: Submitted to Physical Review

A measurement of the KL0+p→KS0+pK^{0}_{L}+p \rightarrow K^{0}_{S}+p reaction between 4 and 14 GeV/c in the range 0.1 ≤∣t∣≤\leq |t| \leq 1.3 GeV2^{2}

The authors present experimental data on the K/sub L//sup 0/p to K/sub S//sup 0/p reaction between 4 and 14 GeV/c in the range 0.1<or approximately= mod t mod <or approximately=2 GeV/sup 2/. This experiment has been performed at the CERN PS, using spark chambers and a large aperture magnet. The results show a break of slope at t=-0.3 GeV/sup 2/. The omega trajectory deduced from the data has an intercept alpha (0)=0.5 and a slope alpha '=0.88. A comparison with various models shows that the non-glip amplitude is dominant. (24 refs)