CERN Accelerating science

The chart of nuclides color coded to show the stable nuclei (288) in black and nuclei that have been shown to exist in grey ($\sim$3350). Approximately 7000 nuclei, inside the drip lines, are predicted to exist~\cite{Erler12}. Nuclei estimated to be involved in the astrophysical $r$ process~\cite{jina} are shown in blue. The isotope $^{207}$Hg is marked with a red asterisk, lying in the region shaded yellow with boundaries at $Z=82$ and $N=126$. The bold lines show the traditional magic numbers. The inset shows the region around $^{207}$Hg. In the inset only, nuclei with at least one known excited state ($\sim$2100 across the entire chart) are shown in green~\cite{nudat,Steer11}.

(a) The low-lying excitation-energy spectrum of $^{207}$Hg as measured via the ($d$,$p$) reaction on $^{206}$Hg at 7.38~MeV/u. States are labeled by their energies in keV and $\ell$ value. Plot (b) is the same spectrum with a linear background subtracted and with fits shown~\cite{fits}.

Angular distributions for the outgoing protons from the ($d$,$p$) reaction on $^{206}$Hg at 7.38~MeV/u. The color of the lines correspond to $\ell=0$ (orange), 2 (maroon), and 4 (yellow) transfer. Transitions are labeled by their excitation energies (in keV) in the residual nucleus and the $\ell$-value corresponding to the best fit angular distribution. The thicker curves represent the best fit angular distribution for the $\ell$-value quoted. Thinner lines are used to show other possible $\ell$ values.

Experimentally determined binding energies of the neutron orbitals at $N=127$ for $^{207}$Hg (this measurement), $^{209}$Pb~\cite{nudat}, and $^{211}$Po~\cite{Bhatia79} compared to Woods-Saxon (WS) calculations of the same orbitals constrained by the Pb and new Hg data. The grey band represents the spread in 21 different models used to calculate $S_n$ for the ground states of nuclei $N=127$ that are commonly used in $r$-process studies~\cite{Mumpower16a}. UNEDF0~\cite{unedf0} and FRDM2012~\cite{frdm2012} are highlighted.