High-Precision Mass Measurements of Proton-Rich Rh, Pd, Cd isotopes in the vicinity of 100Sn and Impact on X-Ray Burst and Supernova Nucleosynthesis

TL;DR

This study reports high-precision mass measurements of proton-rich isotopes near 100Sn, significantly impacting models of X-ray burst and supernova nucleosynthesis by reducing uncertainties and refining reaction flow predictions.

Contribution

First high-precision mass measurements of 91Rh, 92Pd, and 96Cd near 100Sn, improving nuclear data for astrophysical models.

Findings

Mass uncertainties reduced to ~10 keV.

Reaction flow shifted toward A=90 in X-ray burst models.

99Rh identified as influential in the $ u p$-process.

Abstract

Using the ZeroDegree multi-reflection time-of-flight mass spectrograph of the CRISMASS project at RIKEN Radioactive Isotope Beam Factory, we performed high-precision mass measurements of proton-rich nuclei near the doubly magic nucleus 100Sn, achieving uncertainties on the order of 10 keV. The masses of 91Rh, 92Pd, and 96Cd were determined for the first time with high precision, and the accuracy of several additional masses was substantially improved. Incorporating the new data into X-ray burst simulations significantly reduces the abundance uncertainties in the $A$ = 90-100 region, shifting the reaction flow toward $A$ = 90 production and suppressing the synthesis of heavier nuclei. Further investigation of the $\nu p$-process indicates that 99Rh plays a significant role in the reaction flow within the mass region studied. These high-precision mass measurements refine the mass surface near 100Sn and provide critical constraints on models of proton-rich nucleosynthesis.