Search for Neutrinoless Double Beta Decay with NEMO 3 and SuperNEMO

Since 2003 the NEMO~3 experiment has been searching for neutrinoless double beta decay using about 10 kg of enriched isotopes. A limit of T_(1/2)(0nu) > 5.8 10**23 years at 90 % CL has been obtained for 100-Mo from the first two years of data. Several measurements of two-neutrino double beta decays have also been performed. A first NEMO 3 measurement of the half-life of 130-Te is presented, giving a value of T_(1/2)(2nu) = (7.6 +- 1.5 (stat) +- 0.8 (syst)) 10**20 years. In parallel, there is an active R&D programme for the SuperNEMO experiment which is expected to commence data taking in 2012-2013 with 100-200 kg of enriched isotopes.Comment: 6 pages, 3 figures, Proceedings of the 2007 Europhysics Conference on High Energy Physics, in Manchester, England, 19-25 July 200

Characteristics of light charged particle emission in the ternary fission of 250Cf and 252Cf at different excitation energies

The emission probabilities and the energy distributions of tritons, α and ^6He particles emitted in the spontaneous ternary fission (zero excitation energy) of ^250Cf and ^252Cf and in the cold neutron induced fission (excitation energy ≈ 6.5 MeV) of ^249Cf and 251Cf are determined. The particle identification was done with suited ΔE-E telescope detectors, at the IRMM (Geel, Belgium) for the spontaneous fission and at the ILL (Grenoble, France) for the neutron induced fission measurements. Hence particle emission characteristics of the fissioning systems ^250Cf and ^252Cf are obtained at zero and at about 6.5 MeV excitation energies. While the triton emission probability is hardly influenced by the excitation energy, the ^4He and ^6He emission probability in spontaneous fission is higher than for neutron induced fission. This can be explained by the strong influence of the cluster preformation probability on the ternary particle emission probability

The Pulsed Neutron Beam EDM Experiment

We report on the Beam EDM experiment, which aims to employ a pulsed cold neutron beam to search for an electric dipole moment instead of the established use of storable ultracold neutrons. We present a brief overview of the basic measurement concept and the current status of our proof-of-principle Ramsey apparatus

Determination of the Weak Axial Vector Coupling from a Measurement of the Beta-Asymmetry Parameter A in Neutron Beta Decay

We report on a new measurement of the neutron beta-asymmetry parameter $A$ with the instrument \perkeo. Main advancements are the high neutron polarization of $P = 99.7(1)$ from a novel arrangement of super mirror polarizers and reduced background from improvements in beam line and shielding. Leading corrections were thus reduced by a factor of 4, pushing them below the level of statistical error and resulting in a significant reduction of systematic uncertainty compared to our previous experiments. From the result $A_0 = -0.11996(58)$, we derive the ratio of the axial-vector to the vector coupling constant $\lambda = g_\mathrm{A}/g_\mathrm{V} = -1.2767(16)$Comment: 5 pages, 4 figure

Efficient extraction of a collimated ultra-cold neutron beam using diffusive channels

We present a first experimental demonstration of a new method to extract a well-collimated beam of ultra-cold neutrons (UCN) from a storage vessel. Neutrons with too large divergence are not removed from the beam by an absorbing collimation, but a diffuse or semidiffuse channel with high Fermi potential reflects them back into the vessel. This avoids unnecessary losses and keeps the storage time high, which may be beneficial when the vessel is part of a UCN source with long buildup time of a high UCN density

Experimental study of ultracold neutron production in pressurized superfluid helium

We have investigated experimentally the pressure dependence of the production of ultracold neutrons (UCN) in superfluid helium in the range from saturated vapor pressure to 20bar. A neutron velocity selector allowed the separation of underlying single-phonon and multiphonon pro- cesses by varying the incident cold neutron (CN) wavelength in the range from 3.5 to 10{\AA}. The predicted pressure dependence of UCN production derived from inelastic neutron scattering data was confirmed for the single-phonon excitation. For multiphonon based UCN production we found no significant dependence on pressure whereas calculations from inelastic neutron scattering data predict an increase of 43(6)% at 20bar relative to saturated vapor pressure. From our data we conclude that applying pressure to superfluid helium does not increase the overall UCN production rate at a typical CN guide.Comment: 18 pages, 8 figures Version accepted for publication in PR