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Abstract |
A direct measurement of the ground-state-to-ground-state electron-capture decay Q (QEC) value of 97Tc has been conducted employing the high-resolving-power phase-imaging ion-cyclotron-resonance technique with the double Penning trap mass spectrometer JYFLTRAP. The resulting QEC value for 97Tc is 324.82(21) keV, exhibiting a precision approximately 19 times higher than the value adopted in the newest Atomic Mass Evaluation (AME2020) and differing by 1.2 sigma. Furthermore, by combining this refined Q value with nuclear energy-level data for the decay-daughter 97Mo, a potential ultralow Q-value transition 97Tc (9/2+, ground state) -> 97Mo & lowast; [320(1) keV] was detected. The ground-state-to-excited-state electron-capture decay Q value (Q & lowast;EC) of this transition was determined to be 4.8(10) keV, confirming it to be energetically allowed with a confidence level of exceeding 4 sigma. The captures of electrons occupying the L and higher shells for this transition are energetically allowed, giving a value of 2.0(10) keV for the closest distance of Q & lowast; EC to the allowed binding energy of the L1 shell. To predict partial half-lives and energy-release distributions for this transition, the atomic self-consistent many-electron Dirac-Hartree-Fock-Slater method and the nuclear shell model have been employed. Dominant correction terms such as exchange and overlap corrections, as well as shake-up and shake-off effects, were included in the final results. Moreover, in the case of a possible allowed transition, the normalized distribution of released energy in the electron-capture decay of 97Tc to the excited 320-keV state of 97Mo, is compared with that of 163Ho, which is being used for electron-neutrino-mass determination. A pseudoexperiment technique was introduced to calculate error propagation in half-life and the 68% confidence interval for normalized energy distributions. |
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Address |
[Ge, Zhuang; Eronen, Tommi; Ramalho, Marlom; Suhonen, Jouni; Nesterenko, Dmitrii; Kankainen, Anu; Beliuskina, Olga; Hukkanen, Marjut; Jaries, Arthur; Jokinen, Ari; Moore, Iain; Nikas, Stylianos; Ruotsalainen, Jouni; Stryjczyk, Marek; Virtanen, Ville] Univ Jyvaskyla, Dept Phys, POB 35, FI-40014 Jyvaskyla, Finland, Email: zhuang.z.ge@jyu.fi; |
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