G. L. Greene

Nab: Measurement principles, apparatus and uncertainties

The Nab collaboration will perform a precise measurement of a, the electron-neutrino correlation parameter, and b, the Fierz interference term in neutron beta decay, in the Fundamental Neutron Physics Beamline at the SNS, using a novel electric/magnetic field spectrometer and detector design. The experiment is aiming at the 10{sup -3} accuracy level in {Delta}a/a, and will provide an independent measurement of {lambda} = G{sub A}/G{sub V}, the ratio of axial-vector to vector coupling constants of the nucleon. Nab also plans to perform the first ever measurement of b in neutron decay, which will provide an independent limit on the tensor weak coupling.

Study of the dependence of 198Au half-life on source geometry

We report the results of an experiment to determine whether the half-life of {sup 198}Au depends on the shape of the source. This study was motivated by recent suggestions that nuclear decay rates may be affected by solar activity, perhaps arising from solar neutrinos. If this were the case then the {beta}-decay rates, or half-lives, of a thin foil sample and a spherical sample of gold of the same mass and activity could be different. We find for {sup 198}Au, (T{sub 1/2}){sub foil}/(T{sub 1/2}){sub sphere} = 0.999 {+-} 0.002, where T{sub 1/2} is the mean half-life. The maximum neutrino flux at the sample in our experiments was several times greater than the flux of solar neutrinos at the surface of the Earth. We show that this increase in flux leads to a significant improvement in the limits that can be inferred on a possible solar contribution to nuclear decays.

General classification and analysis of neutron β-decay experiments

A general analysis of the sensitivities of neutron ensuremath{beta}-decay experiments to manifestations of possible interaction beyond the standard model is carried out. In a consistent fashion, we take into account all known radiative and recoil corrections arising in the standard model. This provides a description of angular correlations in neutron decay in terms of one parameter, which is accurate to the level of

Fundamental neutron physics beamline at the spallation neutron source at ORNL

~{10}^{ensuremath{-}5}

Precision Measurement of Parity Violation in Polarized Cold Neutron Capture on the Proton: the NPDγ Experiment

. Based on this general expression, we present an analysis of the sensitivities to new physics for selected neutron decay experiments. We emphasize that the usual parametrization of experiments in terms of the tree-level coefficients

Facilities for Fundamental Neutron Physics Research at the NIST Cold Neutron Research Facility

a,A

Neutron Beta Decay Studies with Nab

, and B is inadequate when the experimental sensitivities are at the same or higher level relative to the size of the corrections to the tree-level description.

Upper Bounds on Parity Violating Gamma-Ray Asymmetries in Compound Nuclei from Polarized Cold Neutron Capture.

Abstract We describe the Fundamental Neutron Physics Beamline (FnPB) facility located at the Spallation Neutron Source at Oak Ridge National Laboratory. The FnPB was designed for the conduct of experiments that investigate scientific issues in nuclear physics, particle physics, astrophysics and cosmology using a pulsed slow neutron beam. We present a detailed description of the design philosophy, beamline components, and measured fluxes of the polychromatic and monochromatic beams.

Parity-violating gamma-ray asymmetry in the neutron-proton capture

The NPDγ experiment at the Los Alamos Neutron Science Center (LANSCE) is dedicated to measure with high precision the parity violating asymmetry in the γ emission after capture of spin polarized cold neutrons in para‐hydrogen. The measurement will determine unambiguously the weak pion‐nucleon‐nucleon (πNN) coupling constant fπ1.The NPDGamma experiment at the Los Alamos Neutron Science Center (LANSCE) is dedicated to measure with high precision the parity violating asymmetry in the

NPDGamma: A measurement of the parity-violating gamma asymmetry A γ in n-p capture

gamma