Deuteron-Induced Reactions on the Even-Even Isotopes of Mercury

Over 300 transitions up to 4.5 MeV in excitation energy were observed in the ($d,t$) and ($d,p$) reactions on ${}_{}{}^{204}{}_{}{}^{}\mathrm{Hg}$, ${}_{}{}^{202}{}_{}{}^{}\mathrm{Hg}$, ${}_{}{}^{200}{}_{}{}^{}\mathrm{Hg}$, and ${}_{}{}^{198}{}_{}{}^{}\mathrm{Hg}$ and in the ($d,d^{\prime }$) reaction on ${}_{}{}^{204}{}_{}{}^{}\mathrm{Hg}$, ${}_{}{}^{202}{}_{}{}^{}\mathrm{Hg}$, and ${}_{}{}^{201}{}_{}{}^{}\mathrm{Hg}$ at a bombarding energy of 17 MeV. All targets were isotopically enriched and out-going particles were detected in a split-pole spectrograph having 8- to 14-keV (full width at half maximum) resolution. Over 100 angular distributions in the ($d,p$) and ($d,t$) reactions were measured and compared with distorted-wave Born-approximation calculations to assign $l$ values and extract spectroscopic factors. Two new very low-lying levels were identified - a $p_{\frac{1}{2}}$ at ∼0.005 MeV in ${}_{}{}^{203}{}_{}{}^{}\mathrm{Hg}$ and a $f_{\frac{5}{2}}$ at ∼0.028 MeV in ${}_{}{}^{201}{}_{}{}^{}\mathrm{Hg}$. The ($d,t$) reaction only excited shell-model neutron-hole levels, while the ($d,p$) reaction excited shell-model neutron-particle levels above the $N=126\mathrm{}$ gap with greatest intensity in the heavier mercury isotopes. In the lighter mercury isotopes, the ($d,p$) reaction increasingly excited the neutron-hole states until in ${}_{}{}^{199}{}_{}{}^{}\mathrm{Hg}$ the neutron-hole states are excited with greatest intensity. Fragmentation of all the single-particle and single-hole levels is seen and tends to increase in the lighter mercury isotopes.