Decay spectroscopy in the neutron-rich Mo–Ru–Pd region

¹ Department of Nuclear Physics and Accelerator Applications, The Australian National University, Canberra, ACT 2601, Australia
² Physics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
³ Department of Physics and Astronomy, University of Tennessee, Knoxville, TN, 37966, USA
⁴ Department of Physics, University of Notre Dame, Notre Dame, Indiana 46556, USA
⁵ Facility for Rare Isotope Beams, Michigan State University, East Lansing, Michigan 48824, USA
⁶ Department of Physics, Florida State University, Tallahassee, Florida 32306, USA
⁷ Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, USA
⁸ Argonne National Laboratory, Argonne, Illinois 60439, USA
⁹ Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
¹⁰ Department of Physics and Astronomy, Mississippi State University, Mississippi State, Mississippi 39762, USA
¹¹ Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, USA
² Lawrence Livermore National Laboratory, Livermore, California 94550, USA
³ School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332-0430, USA
⁴ National Nuclear Data Center, Brookhaven National Laboratory, Upton, NY 11973, United States of America

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Published online: 13 May 2026

Abstract

A leading challenge of nuclear-structure research is to understand the properties of nuclides of extreme isospin. Experiments at radioactive-ion-beam facilities, such as the Facility for Rare Isotope Beams in the US, may answer key questions that address diverse topics including fundamental nuclear physics, stellar nucleosynthesis and nuclear applications. The neutron-rich Mo–Ru–Pd (Z = 42 – 46) nuclides are hypothesised to exhibit triaxial-oblate deformation. We performed an experiment with the Facility for Rare Isotope Beams Decay Station initiator (FDSi) to study the structure and decay properties of nuclides in this region. Over 100 different nuclides have been identified in a preliminary analysis of the data. This work presents a first look at several examples between Rb (Z = 37) and Ag (Z = 47). Performance of the FDSi and methods developed to measure ground-state and excited-state lifetimes are presented, and plans for future work are also discussed.