High-precision measurement of the mass difference between 102Pd and 102Ru

The Q-value for the neutrinoless double electron capture on 102Pd, Qϵϵ(102Pd), is determined as the atomic mass difference between 102Pd and 102Ru. A precise measurement of the Qϵϵ(102Pd) at the SHIPTRAP Penning trap showed a more than 10σ 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 Qϵϵ(102Pd) has now been determined with the JYFLTRAP Penning trap at the IGISOL facility in the Accelerator Laboratory of the University of Jyvaskyla. The measurement was performed both with the Time-of-Flight and the Phase-Imaging Ion Cyclotron Resonance techniques. The obtained result, Qϵϵ(102Pd) = 1203.472(45) keV, is eight times more precise and agrees well with the value obtained at SHIPTRAP, Qϵϵ(102Pd) = 1203.27(36) keV, confirming that 102Pd is not a good candidate for a search for neutrinoless double-electron capture.