Mass measurements near the $r$-process path using the Canadian Penning Trap mass spectrometer

TL;DR

This study measured the masses of 40 neutron-rich nuclides near the r-process path with high precision using the Canadian Penning Trap, providing new data that challenges existing models and previous measurements.

Contribution

The paper presents the first high-precision mass measurements of 40 neutron-rich nuclides near the r-process path using the Canadian Penning Trap, revealing systematic deviations from prior data and models.

Findings

Mass measurements agree with previous data where overlapping

Large systematic deviations in beta-endpoint measurements

Differences up to 400 keV from 2003 Atomic Mass Evaluation

Abstract

The masses of 40 neutron-rich nuclides from Z = 51 to 64 were measured at an average precision of $\delta m/m= 10^{-7}$ using the Canadian Penning Trap mass spectrometer at Argonne National Laboratory. The measurements, of fission fragments from a $^{252}$Cf spontaneous fission source in a helium gas catcher, approach the predicted path of the astrophysical $r$ process. Where overlap exists, this data set is largely consistent with previous measurements from Penning traps, storage rings, and reaction energetics, but large systematic deviations are apparent in $\beta$-endpoint measurements. Differences in mass excess from the 2003 Atomic Mass Evaluation of up to 400 keV are seen, as well as systematic disagreement with various mass models.