A new compact beta spectrometer to study weak magnetism – the miniBETA project
Abstract
Precision measurements of correlations in nuclear beta decay to search for exotic (i.e. scalar and tensor) contributions to the weak interaction have now reached the precision level of 1% and below. At this level of precision the effects induced by the strong interactions between the quarks cannot be neglected anymore. The most important of these is the so-called weak magnetism term. We have therefore started a program to study these induced (also called ‘recoil’ terms) both theoretically and experimentally. To this end a new and compact beta spectrometer, miniBETA, is being developed in collaboration with the University of Krakow (K. Bodek et al.). This spectrometer will consist of a multi-wire drift chamber and several energy sensitive (scintillation) detectors. The aim is to perform several high-precision spectrum shape measurements so as to deduce the weak magnetism term, thereby extending the experimental information for this recoil term to isotopes with A>40. The size of the weak magnetism and other recoil terms are also studied on the basis of experimental data available in the literature and via shell model calculations. A better understanding of the size of the different recoil terms will help to include these with better precision in the analysis of correlation measurements, thus leading to a higher sensitivity to possible non-standard model contributions in these observables.
Team
- Senior staff: N. Severijns
- PhD students: V. De Leebeeck, G. Soti
- Associate members: K. Bodek, K. Lojek, J. Zejma (Jagiellonian University, Krakow), A. Kozela (Institute of Nuclear Physics, Krakow)
