  We report on the creation and application of a novel decay network that uses
the latest data from experiment and evaluation. We use the network to simulate
the late-time phase of the rapid neutron capture (r) process. In this epoch,
the bulk of nuclear reactions, such as radiative capture, have ceased and
nuclear decays are the dominant transmutation channels. We find that the decay
from short-lived to long-lived species naturally leads to an isochronic
evolution in which nuclei with similar half-lives are populated at the same
time. We consider random perturbations along each isobaric chain to initial
solar-like r-process compositions to demonstrate the isochronic nature of the
late-time phase of the r-process. Our analysis shows that detailed knowledge of
the final isotopic composition allows for the prediction of late-time evolution
with a high degree of confidence despite uncertainties that exist in
astrophysical conditions and the nuclear physics properties of the most
neutron-rich nuclei. We provide the time-dependent nuclear composition in the
Appendix as supplemental material.
