"aspect" - a new spectrometer for the measurement of the angular correlation coefficient a in neutron beta decay

The combination of the coefficient a of the antineutrino/electron angular c orrelation with the beta asymmetry of the neutron provides a sensitive test for scalar and tensor contributions to the electroweak Lagrangian, as well as for right-handed currents. A method is given for measuring a with high sensitivity from the proton recoil spectrum. The method is based on a magne tic spectrometer with electrostatic retardation potentials such as used for searches of the neutrino mass in tritium beta decay. The spectrometer can also be used for similar studies using radioactive nuclei. (C) 2000 Elsevie r Science B.V. all rights reserved.