Resolve conflicting isobaric mass references in neutron-rich lanthanoid measurements

Ascertain which of the previously published atomic mass data used as isobaric references in the multi-reflection time-of-flight mass spectrograph (MRTOF-MS) analysis are accurate and which have underestimated or incorrect uncertainty evaluations, given that MRTOF-MS time-of-flight linearity reveals up to 3σ discrepancies between reference-based mass determinations for other isobars. This specifically concerns the isobaric reference masses in the neutron-rich lanthanoid region that were employed in this work and subsequently required uncertainty inflation to maintain consistency.

Background

In comparing MRTOF-MS measurements with existing mass data, the authors observed that using reference masses with uncertainties of only a few keV could lead to discrepancies as large as 3σ for other previously measured isobars. Because MRTOF-MS exhibits high linearity in time-of-flight versus ion mass, the pattern of discrepancies suggests a problem with the accuracy or uncertainty evaluation of at least one of the existing mass entries.

To preserve consistency of measured time-of-flight ratios (equivalent to ion mass ratios), the authors increased the uncertainties of certain mass references (e.g., 153Nd, 154Nd, and 155Pr). Identifying which specific mass entries or uncertainty evaluations are incorrect remains unresolved and requires reexamination of the existing mass data.