Speaker
Description
Sensitivity studies identify the $^{102}$Pd$(p,\gamma)^{103}$Ag reaction rate at temperatures $T_9 \simeq 2.0-3.0$ as an important nuclear input for both $p$- and $rp$-process nucleosynthesis. However, experimental information in the relevant Gamow window remains incomplete: no data are available below $E_{\mathrm{c.m.}} = 2.5$~MeV, and measurements at higher energies show sizable discrepancies, differing by factors of $\sim 1.5-3.0$. In this work, the $^{102}$Pd$(p,\gamma)^{103}$Ag cross section was measured for the first time at center-of-mass energies $E_{\mathrm{c.m.}} = 1.88$--2.58~MeV using a high-efficiency anti-Compton--anti-muon $\gamma$-ray spectrometer to suppress environmental and cosmic-ray backgrounds. Cross sections were extracted from characteristic $\gamma$ rays emitted in the decay of $^{103}$Ag, resolving the discrepancies among existing datasets and extending the measurements down to the lowest energies of astrophysical interest. The new low-energy data lead to a revised stellar reaction rate that is up to a factor of two higher than the currently adopted REACLIB and NON-SMOKER values in the astrophysically relevant $p$-process temperature range. These findings demonstrate the importance of improved low-energy experimental input for reducing nuclear physics uncertainties in $p$-process nucleosynthesis calculations.
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