Testing fundamental interactions using beta spectrum shape measurements

Simon Vanlangendonck (KU Leuven, Instituut voor Kern- en Stralingsfysica, Belgium)

The beta spectrum shape is a versatile observable that can address different physics cases depending on the transition studied. Some recent studies focused for example on radionuclide metrology, nuclear theory, and tests for exotic scalar and tensor currents in the weak interaction. Additionally, an accurate determination of the beta spectrum shape in the mass region of the fission fragments is of interest to the evaluation of the reactor neutrino anomaly.

For conventional spectrum shape measurements, electron backscattering is an important limitation, which motivated the development of several approaches to overcome this effect. Experiments (try to) fully encapsulate the source activity or, alternatively, detect the backscattered electrons using for example a multi-wire drift chamber or by installing two detectors face-to-face in a high magnetic field.

This talk will present the details of different experimental approaches, report the status of some ongoing projects and discuss further research possibilities.