6533b82efe1ef96bd1294546

RESEARCH PRODUCT

N=82Shell Quenching of the Classicalr-Process “Waiting-Point” NucleusCd130

subject

description

First $\ensuremath{\beta}$- and $\ensuremath{\gamma}$-spectroscopic decay studies of the $N=82$ $r$-process ``waiting-point'' nuclide $^{130}\mathrm{C}\mathrm{d}$ have been performed at CERN/ISOLDE using the highest achievable isotopic selectivity. Several nuclear-physics surprises have been discovered. The first one is the unanticipatedly high energy of 2.12 MeV for the [$\ensuremath{\pi}{g}_{9/2}\ensuremath{\bigotimes}\ensuremath{\nu}{g}_{7/2}]$ ${1}^{+}$ level in $^{130}\mathrm{I}\mathrm{n}$, which is fed by the main Gamow-Teller transition. The second surprise is the rather high ${Q}_{\ensuremath{\beta}}$ value of 8.34 MeV, which is in agreement only with recent mass models that include the phenomenon of $N=82$ shell quenching. Possible implications of these new results on the formation of the $A\ensuremath{\simeq}130$ $r$-process abundance peak are presented.