No abstract available

[en] Recent measurements of the neutron Β-asymmetry have led to increased interest in the possibility of right handed currents. The Β-decay of polarised ¹⁹Ne is especially sensitive to right handed currents due to its small (∼ 4%) Β-asymmetry. We are measuring the Β-asymmetry of ¹⁹Ne using two large planar Si(Li) detectors, each segmented in four parts to enable detection of multiple backscatters. The detectors have sufficient timing resolution to reconstruct almost all of the backscattered positrons. A modified version of EGS4 code will be used to correct for the few backscatters that are incorrectly reconstructed. The accuracy of the measurement of the asymmetry parameter is expected to be about 1%. At this level, theoretical uncertainties dominate the limits on right handed currents

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[en] An ongoing measurement of the parity violating beta asymmetry in ¹⁹Ne is discussed. This asymmetry is particularly sensitive to extensions to the standard model which include right-handed weak currents. The ¹⁹Ne beta asymmetry together with the ¹⁹Ne half life provides limits on right-handed currents which are complementary to the limits derived from neutron beta decay. Experimental details are discussed with an emphasis on the determination of systematic errors. (author)

[en] The decay of "1"9O(β"-) and "1"9Ne(β"+) implanted in niobium in its superconducting and metallic phases was measured using purified radioactive beams produced by the SPIRAL GANIL facility. Half-lives and branching ratios measured in the two phases are consistent within a 1σ error bar. This measurement casts strong doubts on the predicted strong electron screening in a superconductor, the so-called super-screening. The measured difference in screening potential energy is 110(90) eV for "1"9Ne and 400(320) eV for "1"9O. Precise determinations of the half-lives were obtained for "1"9O, 26.476(9) s, and for "1"9Ne, 17.254(5) s. (authors)

[en] The half-life of ¹⁹Ne was measured using a real-time digital multiparametric acquisition system, providing an accurate time stamp and relevant information on the detector signals for each decay event. An exhaustive offline analysis of the data gave unique access to experimental effects potentially biasing the measurement. After establishing the influence factors impacting the measurement such as after-pulses, pile-up, gain, and baseline fluctuations, their effects were accurately estimated and the event selection optimized. The resulting half-life, 17.2569 ± 0.0019(stat) ± 0.0009(syst) s, is the most precise up to now for ¹⁹Ne. It is found to be in agreement with two recent precise measurements and not consistent with the most recent one [L.J. Broussard et al., Phys. Rev. Lett. 112, 212301 (2014) by 3.0 standard deviations. The full potential of the technique for nuclei with half-lives of a few seconds is discussed. (authors)

[en] The ¹⁹Ne(p,γ)²⁰Na reaction may influence considerably the reaction flow between the CNO and NeNa mass regions in high temperature hydrogen burning conditions. The 447 keV resonance has been studied by exploiting radioactive ¹⁹Ne beams with novel detection techniques to measure β⁺-delayed α radioactivity of ²⁰Na nuclei produced in reactions with polyethylene targets. A 90% C.L. upper limit of 18 meV for the resonance strength has been determined and implications for the spin assignment of the 2.646 MeV state in ²⁰Na and the stellar reaction are discussed

No abstract available

[en] Several experiments are in progress which seek to test the standard electroweak model through measurements of fundamental symmetries in β-decay. One such measurement is a test of the V - A structure of the electroweak interaction through an absolute measurement of the β-asymmetry in ¹⁹Ne. This angular correlation can be written A(J · p_β), where J is the ¹⁹Ne spin, p_β is the positron momentum, and A is a coefficient characterizing the size of the asymmetry. Recently obtained results from new measurements of this asymmetry will be presented. Because absolute measurements of the β-asymmetry are increasingly limited by systematic uncertainties, the authors strategies for minimizing and/or characterizing these uncertainties are discussed. Another measurement underway is a determination of the time-reversal non-invariant (T non-invariant) triple correlation D(J · p_β x p_ν), where p_ν is the neutrino momentum, in which they hope to reach the level at which final state effects are expected to be present. Measurements of T invariance in β-decay provide valuable constraints to extensions of the standard model. Results concerning a new technique for producing laser-aligned ³⁶K which may be useful in future T invariance studies will be discussed as well

No abstract available