Year: 2023
Type: preprint
Abstract: Highly precise measurements of the $^{99}$Tc 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 $Q_β=$295.82(16) keV and $g_A^{\text{eff}} = 1.530 (83)$. Furthermore, we derived the mean energy of the beta spectrum $\overline{E}_β$=98.45(20) keV, $\log f = -0.47660 (22)$ and $\log ft = 12.3478 (23)$.
Source: arXiv (Cornell University)
Authors: Paulsen, Michael, Ranitzsch, Philipp, Loidl, Martin, Rodrigues, Matias, Kossert, Karsten, Mougeot, Xavier, Singh, Abilasha, Leblond, Sylvain, Beyer, Jörn, Bockhorn, Lina, Enss, Christian, Wegner, Mathias, Kempf, Sebastian, Nähle, Ole
Institutions: Physikalisch-Technische Bundesanstalt, Heidelberg University, Commissariat à l'Énergie Atomique et aux Énergies Alternatives, Université Paris-Saclay, CEA Paris-Saclay - Etablissement de Saclay, Laboratoire d'Intégration des Systèmes et des Technologies, Laboratoire National Henri Becquerel, Karlsruhe Institute of Technology
Language: English
Subfield: Radiation
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Awards: G1614887332, G434337789, G5053235250
OpenAlex ID: W4387076144