beta asymmetry parameter in the decay of In-114

The beta-asymmetry parameter A approximate to for the pure Gamow-Teller decay of In-114 is reported. The low-temperature nuclear orientation method was combined with a GEANT4-based simulation code allowing us, for the first time, to address in detail the effects of scattering and the magnetic field. The result, A approximate to=-0.994 +/- 0.010(stat)+/- 0.010(syst), constitutes the most accurate value for the asymmetry parameter of a nuclear beta transition to date. The value is in agreement with the Standard Model prediction of A approximate to=-1 and provides new limits on tensor-type charged weak currents.