2024/04/04 by De Keukeleere, L., Rozpedzik, D., Severijns, N. +5 · 1 citation
#FOS: Physical sciences #Nuclear Experiment (nucl-ex)
paper · doi:10.48550/arxiv.2404.03140
Spectrum shape measurements in nuclear β decay can be used to test physics beyond the Standard Model with results being complementary to high-energy collider experiments. In particular, Beyond Standard Model sensitivity of the weak interaction is expressed through the so-called Fierz interference term. Additionally, the β spectrum shape is a useful tool to probe Standard Model effects, among which the most prominent is weak magnetism, a higher-order recoil correction induced by nuclear pion exchange. To study effects in the β spectrum shape at a precision level competitive with the LHC, a new spectrometer was designed and built. It consists of a 3D low-pressure gas electron tracker and a plastic scintillator used for triggering the data acquisition and recording the β particle energy. In this Letter, the results from β spectrum shape measurements on the allowed Gamow-Teller transition 114In → 114Sn are presented, including a first extraction of the weak magnetism form factor in the high nuclear mass range and a new estimate of the 90% confidence interval for the Fierz interference term.