Precise measurements of the γ-ray intensities following the β decay of Ce144 and Nd147

For many fission products, the $\gamma$ rays emitted following $\beta$ decay provide an easily detectable signature that can be used to identify their quantities and distributions in a sample. As a result, $\gamma$-ray spectroscopy is often exploited to study fission-product yields, provided sufficiently accurate information on the $\gamma$-ray intensities is available. In many cases, the uncertainties in the existing nuclear data are large enough that they compromise the precision achievable for modern experiments and applications. In this paper, we present high-precision results for the absolute $\gamma$-ray emission intensities for the most intense transitions in the $\beta$ decays of ${}^{144}\mathrm{Ce}$ and ${}^{147}\mathrm{Nd}$. We measured these intensities to $\lesssim 1\%$ accuracy by producing radiopure samples with fission-product beams at CARIBU and detecting the emitted radiation with a $4\pi \beta$ counter and a meticulously efficiency-calibrated high purity germanium detector at Texas A&M University.