High-precision measurements of the atomic mass and electron-capture decay Q value of 95Tc

• Published in: Physics letters. B Vol. 859; p. 139094
• Main Authors: Ge, Zhuang, Eronen, Tommi, Sevestrean, Vasile Alin, Niţescu, Ovidiu, Stoica, Sabin, Ramalho, Marlom, Suhonen, Jouni, de Roubin, Antoine, Nesterenko, Dmitrii, Kankainen, Anu, Ascher, Pauline, Ayet San Andres, Samuel, Beliuskina, Olga, Delahaye, Pierre, Flayol, Mathieu, Gerbaux, Mathias, Grévy, Stéphane, Hukkanen, Marjut, Jaries, Arthur, Jokinen, Ari, Husson, Audric, Kahl, Daid, Kostensalo, Joel, Kotila, Jenni, Moore, Iain, Nikas, Stylianos, Stryjczyk, Marek, Virtanen, Ville
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.12.2024
• Subjects: Electron capture; Mass measurements; Penning trap; Ultra-low Q value; Electron capture; Penning trap; Mass measurements; Ultra-low Q value
• ISSN: 0370-2693
• DOI: 10.1016/j.physletb.2024.139094

A direct measurement of the ground-state-to-ground-state electron-capture decay Q value of 95Tc has been performed utilizing the double Penning trap mass spectrometer JYFLTRAP. The Q value was determined to be 1695.92(13) keV by taking advantage of the high resolving power of the phase-imaging ion-cyclotron-resonance technique to resolve the low-lying isomeric state of 95Tc (excitation energy of 38.910(40) keV) from the ground state. The mass excess of 95Tc was measured to be −86015.95(18) keV/c2, exhibiting a precision of about 28 times higher and in agreement with the value from the newest Atomic Mass Evaluation (AME2020). Combined with the nuclear energy-level data for the decay-daughter 95Mo, two potential ultra-low Q-value transitions are identified for future long-term neutrino-mass determination experiments. The atomic self-consistent many-electron Dirac–Hartree–Fock–Slater method and the nuclear shell model have been used to predict the partial half-lives and energy-release distributions for the two transitions. The dominant correction terms related to those processes are considered, including the exchange and overlap corrections, and the shake-up and shake-off effects. The normalized distribution of the released energy in the electron-capture decay of 95Tc to excited states of 95Mo is compared to that of 163Ho currently being used for electron-neutrino-mass determination.