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Both components of the transverse electron polarization have been measured in free neutron decay. The T-odd, P-odd correlation coefficient associated with polarization component perpendicular to the neutron polarization and electron momentum, was found to be R = 0:006 ± 0:012 ± 0:005. This value is consistent with time reversal invariance, and significantly improves limits on the relative strength of imaginary scalar couplings in the weak interaction. The value obtained for the T-even, P-even correlation coefficient connected with the second transversal polarization component, N = 0:065 ± 0:012 ± 0:004, agrees with the Standard Model expectation providing an important sensitivity test of the experimental setup. [ABSTRACT FROM AUTHOR]

Precision correlation measurements in nuclear beta decay using atom and ion traps have made significant progress since the last ENAM2004 Conference. We review here the achievements and plans of different projects and discuss for each of them their potential to contribute to the determination of the Vud element of the Cabibbo-Kobayashi-Maskawa quark mixing matrix. This matrix element has traditionally been determined from the analysis of data in nuclear superallowed 0+ $ \rightarrow$ 0+ transitions, neutron decay and pion beta decay but can also independently be determined from data in nuclear mirror transitions. This requires the measurement of correlation parameters in such decays to determine the Gamow-Teller to Fermi mixing ratio which, in most cases, dominates the error on the extracted value of | Vud| . [ABSTRACT FROM AUTHOR]

The aim of this work is the experimental observation of and research into a rare neutron mode, the radiative beta decay, where a new particle, the radiative gamma quantum, is formed along with the expected decay products: a beta electron, a recoil proton, and an antineutrino. The discovery of this rare neutron decay mode was conducted through identification of triple-coincidence events: simultaneous registration of a beta electron, a proton, and a radiative gamma quantum. The ordinary neutron decay was registered by double coincidences of a beta electron and a recoil proton. The statistics collected allow one to deduce the branching ratio (BR) BR = (3.2 ± 1.6) × 10−3 (90% C.L.) in the gamma energy region greater than 35 keV. This value of BR is consistent with standard electroweak theory. [ABSTRACT FROM AUTHOR]

The positrons and coincident gamma-rays following the pure Fermi 0+ → 0+ branch of β+-decay in14O were measured. The Doppler shift of the γ-quantum observed is sensitive to the beta-neutrino correlation coefficient, which is unity (α = 1) in the absence of scalar coupling. The interatomic interaction of recoiling daughters was noticed, which has prevented to obtain an improved result for scalar coupling despite of the excellent statistical accuracy of the measurement. At the same time, it was shown that the method described can be used as a very sensitive and flexible tool to probe the interatomic interactions in matter at the hundred eV energy level. Perspectives in this direction as well as the future angular-correlation experiments aimed to search for scalar coupling in beta-decay are discussed. [ABSTRACT FROM AUTHOR]

The article presents the authors' comments to the article "Observation of the Neutron Radiative Decay" published in the July 2006 issue of the journal. The authors do not endorse the claim of the writers to have observed radioative neutron decay because according to them, the interpretation and the presentation of the data in the article is not comprehensive so, one cannot seriously extract any qualitative information about neutron decay, particularly a branching ratio of an unobserved effect.

Abstract: The measurement of the asymmetry parameter in nuclear decay is a potentially very sensitive tool to search for non – components in the charge-changing weak interaction. To reach the required precision (percent level) all effects that modify the emission pattern of the radiation, i.e. the geometry of the setup, the effect of the magnetic field on the trajectories of particles as well as (back)scattering in the source, on the sample holder and on the detector, have to be correctly taken into account in the analysis of the data. A thorough study of these effects and a new method based on detailed GEANT4 Monte-Carlo simulations that was developed for this purpose is presented here. The code was developed for asymmetry measurements by means of the Low Temperature Nuclear Orientation (LTNO) method, but can in principle be generalized to other experimental setups using other polarization techniques. [Copyright &y& Elsevier]

The WITCH experiment will measure the recoil energy spectrum of the daughter ions in β-decay. The main parts of the experiment are two Penning traps and a subsequent retardation spectrometer. The β-decays take place in the ion cloud in the decay trap. Since the ion cloud is in vacuum and due to the cylindrical structure of the trap, the recoiling daughter ions can leave the cloud and the trap without any significant energy loss and can be energy analyzed in the retardation spectrometer.The WITCH experiment is set up foremost to study the electroweak interaction by measuring the β–ν angular correlation in nuclear β-decay which can be inferred from the shape of the energy spectrum of the recoil ions. In the beginning the experiment will focus on pure Fermi decays which will allow to search for additional scalar coupling in the weak interaction. Since Penning traps have no restrictions regarding the element to be trapped the most suitable isotope can be picked for this purpose. The WITCH experiment is presently being set up at ISOLDE. Status and perspectives of the experiment will be presented in the following. [Copyright &y& Elsevier]

Abstract: First results are presented from an experiment that aims at the simultaneous determination of both transversal polarization components of electrons emitted in the decay of free neutrons – two observables that have never before been addressed experimentally. They reveal first-order sensitivity to real and imaginary parts of the exotic scalar and tensor interactions. [Copyright &y& Elsevier]