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Highlights • The submitted manuscript describes the measurement of mass difference between Pd 102 and Ru 102 performed with the Penning-trap mass spectrometer JYFLTRAP. • A very careful evaluation on the atomic mass difference of the pair Pd 102 – Ru 102 in the Atomic Mass Evaluation based on the analysis of full bulk of spectroscopy information for nearest nuclides showed a dramatic deviation of more than 10 σ with the mass measurement performed at the SHIPTRAP Penning trap. • Since the evaluated mass difference was obtained via numerous local connections in β- and electron capture decays and very precise (n , γ) data which agree with each other perfectly, the reliability of the SHIPTRAP measurement was challenged. • To solve the problem, the measurement of the mass difference Pd 102 – Ru 102 has been undertaken at the JYFLTRAP Penning-trap setup using both the Time-of-Flight and the Phase-Imaging Ion Cyclotron Resonance techniques. • The obtained result is around 8 times more precise and in excellent agreement with the value obtained at SHIPTRAP. This agreement manifests the reliability of the Penning trap mass spectrometry. Abstract The Q -value for the neutrinoless double electron capture on 102Pd, Q ϵϵ (102Pd), is determined as the atomic mass difference between 102Pd and 102Ru. A precise measurement of the Q ϵϵ (102Pd) at the SHIPTRAP Penning trap showed a more than 10 σ deviation to the adopted Atomic Mass Evaluation (AME) value. The reliability of the SHIPTRAP measurement was challenged because the AME value was based on numerous experiments including β and electron capture decays and very precise (n , γ) data, all agreeing with each other. To solve the discrepancy, the Q ϵϵ (102Pd) has now been determined with the JYFLTRAP Penning trap at the IGISOL facility in the Accelerator Laboratory of the University of Jyväskylä. The measurement was performed both with the Time-of-Flight and the Phase-Imaging Ion Cyclotron Resonance techniques. The obtained result, Q ϵϵ (102Pd) = 1203.472(45) keV, is eight times more precise and agrees well with the value obtained at SHIPTRAP, Q ϵϵ (102Pd) = 1203.27(36) keV, confirming that 102Pd is not a good candidate for a search for neutrinoless double-electron capture. [ABSTRACT FROM AUTHOR]

A precise determination of the ground state 111In (9 / 2 +) electron capture to ground state of 111Cd (1 / 2 +) Q value has been performed utilizing the double Penning trap mass spectrometer, JYFLTRAP. A value of 857.63(17) keV was obtained, which is nearly a factor of 20 more precise than the value extracted from the Atomic Mass Evaluation 2020 (AME2020). The high-precision electron-capture Q value measurement along with the nuclear energy level data of 866.60(6) keV, 864.8(3) keV, 855.6(10) keV, and 853.94(7) keV for 111Cd was used to determine whether the four states are energetically allowed for a potential ultra-low Q -value β decay or electron-capture decay. Our results confirm that the excited states of 866.60(6) keV with spin-parity (J π) of 3/2+ and 864.8(3) keV with J π = 3 / 2 + are ruled out due to their deduced electron-capture Q value being smaller than 0 keV at the level of around 20 σ and 50 σ , respectively. Electron-capture decays to the excited states at 853.94(7) keV (J π = 7 / 2 +) and 855.6(10) keV (J π = 3 / 2 +), are energetically allowed with Q values of 3.69(19) keV and 2.0(10) keV, respectively. The allowed decay transition 111In (9/2+) → 111Cd (7/2+), with a Q value of 3.69(19) keV, is a potential new candidate for neutrino-mass measurements by future EC experiments featuring new powerful detection technologies. The results show that the indium level 2 p 1 / 2 for this decay branch leads to a significant increase in the number of EC events in the energy region sensitive to the electron neutrino mass. [ABSTRACT FROM AUTHOR]