Speaker
Description
Measurements of the shape of the β energy spectrum are interesting to study, e.g., nuclear structure [1] and, when high precision is reached, allow to test for exotic scalar and/or tensor currents in the weak interaction [2].
However, the experimental precision reached is limited by the incomplete energy deposition caused by backscattering. In the WISArD set-up, this problem is alleviated using two detectors placed in a high magnetic field. This configuration ensures a 4π solid angle and guides backscattered β particles towards the opposite detector. In December 2020 the InESS@WISArD [3] proof-of-principle experiment measured the β spectrum shape of
For subsequent experiments, we are investigating the possibility of replacing the scintillators with lithium doped silicon (Si(Li)) detectors. These have a superior energy resolution, i.e., an improvement of about a factor of 50 [3,4], and a significantly lower energy threshold, i.e., around 1.5 keV [4], compared to 65 keV [3]. Such detector characteristics can drastically improve the situation for of the systematic effects encountered with the scintillators, thus making the installation of these Si(Li) detectors a promising path for further advances in β spectrum shape studies.
References:
[1] Severijns, N., Hayen, L., De Leebeeck, V., Vanlangendonck, S., Bodek, K., Rozpedzik, D., and Towner, I. S. Ft values of the mirror β transitions and the weak-magnetism-induced current in allowed nuclear β decay. Physical Review C 107, 1 (Jan 2023), 015502.
[2] Hayen, L., Severijns, N., Bodek, K., Rozpedzik, D., and Mougeot, X. High precision analytical description of the allowed β spectrum shape. Reviews of Modern Physics 90, 1 (Mar 2018), 15008.
[3] S. Vanlangendonck. The effect of weak magnetism on the shape of the
[4] C. Knapen. Characterisation of Si(Li) Detectors for β Spectrum Shape Measurements. Master’s thesis, KU Leuven, 2023.
