First Results from the CARIBU Facility: Mass Measurements on the r-Process Path

TL;DR

This paper reports initial mass measurements of neutron-rich isotopes near the r-process path using the Canadian Penning Trap at CARIBU, revealing significant deviations from existing models and impacting astrophysical nucleosynthesis simulations.

Contribution

First mass measurements of neutron-rich nuclides at the r-process path using the Canadian Penning Trap, highlighting discrepancies with models and influencing astrophysical simulations.

Findings

Mass measurements achieved at 100 ppb precision.

Significant increases in waiting times at Sn and Sb compared to models.

Existing mass models are inadequate for accurate r-process predictions.

Abstract

The Canadian Penning Trap mass spectrometer has made mass measurements of 33 neutron-rich nuclides provided by the new Californium Rare Isotope Breeder Upgrade (CARIBU) facility at Argonne National Laboratory. The studied region includes the 132Sn double shell closure and ranges in Z from In to Cs, with Sn isotopes measured out to A = 135, and the typical measurement precision is at the 100 ppb level or better. The region encompasses a possible major waiting point of the astrophysical r process, and the impact of the masses on the r process is shown through a series of simulations. These first-ever simulations with direct mass information on this waiting point show significant increases in waiting time at Sn and Sb in comparison with commonly used mass models, demonstrating the inadequacy of existing models for accurate r-process calculations.