M. Obolensky

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

Search for neutrino oscillations at 15, 40 and 95 meters from a nuclear power reactor at Bugey

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.

Study of reactor antineutrino interaction with proton at Bugey nuclear power plant

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

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

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

Comparison of anti-neutrino reactor spectrum models with the Bugey-3 measurements

Abstract We report on high statistics measurements of neutrino energy spectra carried out at 15, 40 and 95 meters from a 2800 Megawatt reactor, using detection modules filled with 6 Li-loaded liquid scintillator. No oscillations have been observed. Exclusion zones for oscillation parameters are deduced from the observed consistency of the spectra at the three distances. The minimum excluded values of the δm 2 and sin 2 2θ parameters are 1 × 10 −2 eV 2 and 2 × 10 −2 (at 90% CL), respectively.

Limits on electrochemically induced fusion of deuterium by neutron flux measurements

Abstract We report on a high precision measurement at 15m from a 2800 MWth reactor in which 300 000 events of electron antineutrino interactions with proton have been detected using an integral method. The cross section of the neutron inverse beta-decay process has been measured with an accuracy of 1.4%. The ratio of measured cross section to the expected one in the standard V-A theory of weak interactions is: σ ⨍ /σ V−A = 98.7% ± 1.4% ± 2.7% = 0.987 ± 0.030 .

The waveform digitiser of the Double Chooz experiment: performance and quantisation effects on photomultiplier tube signals

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.

Erratum to: “Limits on neutrino oscillations from the CHOOZ experiment” [Phys. Lett. B 466 (1999) 415–430]

Abstract The Bugey 3 neutrino oscillation experiment has provided high statistics neutrino energy spectra recorded at 15 and 40 meters from a nuclear reactor core. Assuming no oscillations, the measured spectra favor a model of reactor spectrum based on the beta spectra measured at ILL.