High precision measurement of the ⁹⁹Tc β spectrum

2023/09/25 by Michael Paulsen, Philipp Ranitzsch, Paulsen, Michael +24
Health Professions · Physics and Astronomy · #FOS: Physical sciences #Instrumentation and Detectors (physics.ins-det) #Neutrino Physics Research #Nuclear Experiment (nucl-ex) #Nuclear Theory (nucl-th) #Radioactive Decay and Measurement Techniques #Radioactivity and Radon Measurements

paper · pdf · doi:10.48550/arxiv.2309.14014

openalex publication_date 2023/09/25 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/01

Abstract

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 Q_β=295.82(16) keV and g_A^eff = 1.530 (83). Furthermore, we derived the mean energy of the beta spectrum E_β=98.45(20) keV, log f = -0.47660 (22) and log ft = 12.3478 (23).

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