Highly precise measurements of the 99Tc beta spectrum were performed in two laboratories using metallic magnetic calorimeters. Independent sample preparations, evaluation methods and analyses yield consistent results and the spectrum could be measured down to less than 1 keV. Consistent beta spectra were also obtained via cross-evaluations of the experimental data sets. An additional independent measurement with silicon detectors in a 4π configuration confirms the spectrum shape above 25 keV. Detailed theoretical calculations were performed including nuclear structure and atomic effects. The spectrum shape was found to be sensitive to the effective value of the axial-vector coupling constant. Combining measurements and predictions, we extracted Qβ=295.82(16) keV and gAeff=1.530(83). Furthermore, we derived the mean energy of the beta spectrum Eβ=98.45(20) keV, logf=−0.47660(22) and logft=12.3478(23).
@article{arxiv.2309.14014,
title = {High precision measurement of the $^{99}$Tc $\beta$ spectrum},
author = {Michael Paulsen and Philipp Ranitzsch and Martin Loidl and Matias Rodrigues and Karsten Kossert and Xavier Mougeot and Abilasha Singh and Sylvain Leblond and Jörn Beyer and Lina Bockhorn and Christian Enss and Mathias Wegner and Sebastian Kempf and Ole Nähle},
journal= {arXiv preprint arXiv:2309.14014},
year = {2023}
}
Comments
15 pages, 9 figures, adjusted the legend symbols in figures 6-9 to the format (italics, subscripts etc.) used in the text [version 2], corrected assignment of author affiliations and capital lettering in references [version 3]