Speaker
Description
Precision measurements of observables in nuclear and neutron beta decay to provide important information on the structure and symmetries of the weak interaction at low energy. Among the empirical foundations of the electroweak Standard Model the assumptions of maximal parity violation, vector and axial-vector character and massless neutrinos are directly related to the experiments performed with the nuclear and neutron beta decay while the exotic scalar and tensor interactions are excluded. The shape of the beta spectrum in nuclear beta decay and the neutron beta decay correlation coefficients are sensitive to these exotic interactions and therefore are an excellent probes for searching the new physics beyond the Standard Model.
This contribution will focus on the precision beta spectrum shape measurement of 114In isotope. The measurements were carried out by using the miniBETA spectrometer consisting of a low-mass, low-Z multi-wire gas tracker and a plastic scintillator energy detector. The result of the extraction of the weak magnetism form factor from spectrum shape of 114In with discussion of the systematic error budget will be presented.
The measurement technique for low energy electrons used in miniBETA project will be also applied for neutron decay correlation experiment which will measure simultaneously seven neutron correlation coefficients that depend on the transverse electron polarization. Five of these correlations: H, L, S , U and V were never attempted experimentally before. The expected ultimate sensitivity of the proposed experiment that currently takes off on the cold neutron beamline PF1B at the Institut Laue-Langevin, Grenoble, France, is comparable to that of the ongoing and planned electron spectrum shape measurements in neutron and nuclear beta decays but offers completely different systematics and additional sensitivity to imaginary parts of the scalar and tensor couplings. The current status of the BRAND project will be reported and as well as plans for the future measurements will be discussed.
