Mass measurements of neutron-rich indium isotopes for r -process studies

Abstract

A new series of neutron-rich indium mass measurements is reported from the TITAN multiple-reflection time-of-flight mass spectrometer (MR-TOF-MS). These mass measurements cover In125−134 (N=76–85) and include ground states as well as isomeric states. The masses of nuclei in this region are known to be of great importance for accurately modeling r-process nucleosynthesis, and the significance of the reported neutron-rich indium masses is discussed in this context. Results are compared with earlier experimental data where available as well as theoretical mass models. The measurements reported here include the first mass measurements of In133,134, as well as the first direct mass measurement of In132. The masses of In125−131 ground states and several isomers were previously measured to higher precision by Penning trap mass spectrometry, which also resolved some low-lying isomers that could not be resolved in this work. The earlier Penning trap measurements serve as excellent cross-checks for the MR-TOF-MS measurements, and in some cases the MR-TOF-MS measurements improve the literature uncertainties of higher-lying isomer masses and excitation energies. A new isomeric state for In128, recently reported for the first time by the JYFLTRAP group, is also confirmed by the TITAN MR-TOF-MS, with a measured excitation energy of 1813(17) keV.Received 24 November 2020Accepted 8 February 2021DOI:https://doi.org/10.1103/PhysRevC.103.025811©2021 American Physical SocietyPhysics Subject Headings (PhySH)Research AreasBinding energy & massesNuclear astrophysicsr processProperties90 ≤ A ≤ 149TechniquesSpectrometers & spectroscopic techniquesNuclear Physics