D.H. Koang

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

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.

Final results on the neutrino magnetic moment from the MUNU experiment

Abstract The MUNU detector was designed to study ν ¯ e e − elastic scattering at low energy. The central component is a Time Projection Chamber filled with CF 4 gas, surrounded by an anti-Compton detector. The experiment was carried out at the Bugey (France) nuclear reactor. In this Letter we present the final analysis of the data recorded at 3 bar and 1 bar pressure. Both the energy and the scattering angle of the recoil electron are measured. From the 3 bar data a new upper limit on the neutrino magnetic moment μ e short 9 × 10 −11 μ B at 90% CL was derived. At 1 bar electron tracks down to 150 keV were reconstructed, demonstrating the potentiality of the experimental technique for future applications in low energy neutrino physics.

Limits on the neutrino magnetic moment from the MUNU experiment

Abstract The MUNU experiment was carried out at the Bugey nuclear power reactor. The aim was the study of ν e e − elastic scattering at low energy. The recoil electrons were recorded in a gas time projection chamber, immersed in a tank filled with liquid scintillator serving as veto detector, suppressing in particular Compton electrons. The measured electron recoil spectrum is presented. Upper limits on the neutrino magnetic moment were derived and are discussed.

Indication for neutrino oscillation from a high statistics experiment at the bugey reactor

Abstract The energy spectrum of electron antineutrinos has been measured at two distances, 13.6 and 18.3. meters, from the core of a PWR power reactor at Bugey (France). About 63 000 antineutrino events have been recorded using the inverse β-decay reaction ν e+p→n+e+. We observe a difference in the counting rates between the two positions. The compatibility of the results with solutions in a two-neutrino oscillations analysis is discussed.

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

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.

Evidence of parity violation in neutron capture by 117Sn

Abstract An asymmetry measurement in the radiative capture of polarized cold neutrons in the raction 117Sn(n, γ) 118Sn is reported. The result a = (4.4 ± 0.6) × 10−4 gives a clear evidence of a parity non-conserving effect.

Parity non-conservation in the radiative capture of polarized neutrons by 35Cl

We report a measurement of the forward-backward asymmetry in the radiative capture of polarized cold neutrons in the reaction 35Cl(n, γ)36Cl where 36Cl is in the ground state. The measured value of the asymmetry is a = (1.57 ± 0.531) × 10−4. We deduce the mixing between the 2+ capture level and the neighboring 2− levelto be 〈2−¦Hp.v.¦2+〉 = −0.25 ± 0.08 eV before corrections. A measurement of the integral asymmetry of all γ-rays in the neutron capture by 35Cl leads to agreement with measurements at Leningrad.

Parity violation in nd capture

Abstract We have found an asymmetric angular distribution of the 6.24 MeV photon about the spin direction of the neutron of the form (1+A cos θ), where θ is the angle between photon momentum and incident neutron spin. We find A=(7.8 ± 3.4) × 10−6 where the error is statistical. In addition there is an overall scale error. The value is larger than predictions based on either Cabbibo or gauge theoretical models, which give values of A between 10−6 and 10−7. The error is too large to claim a discrepancy with theory.

A search for axions at a power reactor

Abstract A search has been conducted for the axion at the Bugey reactor which is owned and operated by Electricite de France. The axion production should be proportional to the magnetic transition of np capture, and be detectable by its decay into 2γ rays. No signal was observed in this measurement. Also no axion signal was seen from a single proton magnetic transition of 97Nb. Using those two results, the axion can be excluded with a mass up to 1 MeV in the Peccei-Quinn formalism.

Limits on electrochemically induced fusion of deuterium by neutron flux measurements

Abstract Limits on the neutron flux produced by electrochemically induced nuclear fusion reactions have been set using a very efficient and low background detector based on 6 Li doped liquid scintillator to detect the 2.45 MeV neutron. These limits are of the order of 50 neutrons/h for differet electrolysis experimental conditions and are at least 30 times lower than the claimed positive results of Fleischmann and Pons, and of Jones et al.