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Abstract

Two topics of fundamental physics are considered where nuclides with a low beta-decay energy are of high interest, namely nuclear astrophysics and neutrino physics. A few relevant ground-to-ground beta-transitions were addressed by Penning-trap mass spectrometry (PT-MS), employing the Shiptrap (GSI, Darmstadt) and Isoltrap (CERN, Geneva) facilities.

In nuclear astrophysics the decay energy of a nuclide is an important spectroscopic parameter. Thus, in the case of the pure s-process nuclide 123Te, it was shown that when its decay energy is accurately and precisely known, the complete decay scheme in a hot stellar environment can be reliably reconstructed. It is shown that at typical s-process conditions the half-life of 123Te can be by many orders of magnitude shorter than the terrestrial value. This circumstance may be used, for example, for tests of astrophysical models in the A = 123 mass region.

In neutrino physics, low-energy beta-transitions can be used for determination of the neutrino rest mass. The decay energies (Q-values) of 131Cs and 202Pb were determined. It turned out that the nuclide 202Pb can hardly be used for the neutrino mass determination due to its too high Q-value, whereas 131Cs can be confidently excluded from the consideration since the examined beta-transition is energetically forbidden. The directly measured Q-value of 187Re has shown that on the level of our present accuracy of 33 eV there are no unexpected systematic effects inherent in cryogenic microcalorimetry (CM), which was used for the beta-spectra acquisition of 187Re. A specific problem in neutrino physics is the existence of sterile neutrinos, especially those which can contribute to the so-called Warm Dark Matter. It is shown that the combined efforts of PT-MS and CM may contribute to the keV sterile neutrino search in electron capture in a variety of nuclides.