Feeding of the 11/2$^{-}$ isomers in $^{191,193}$Ir and $^{197}$Au.

The ($n,n^{\prime}\gamma$) reaction was used to study excited states and to measure absolute partial $\gamma$-ray cross sections in $^{191}$Ir, $^{193}$Ir and $^{197}$Au. The data were taken using the GEANIE spectrometer comprised of 26 high-purity Ge detectors with 20 BGO escape-suppression shields. The broad-spectrum pulsed neutron source of the Los Alamos Neutron Science Center's WNR facility provided neutrons in the energy range from 0.6 to 250 MeV. The time-of-flight technique was used to determine the incident neutron energies. The absolute partial cross sections for hundreds of $\gamma$-rays from several reaction channels were determined. The partial $\gamma$-ray cross sections of several transitions feeding directly the 11/2$^{-}$ isomers and ground states in $^{191,193}$Ir and $^{197}$Au were obtained. In the case of $^{197}$Au, where the structure above the 11/2$^{-}$ isomer was not known before, the partial $\gamma$-ray cross sections and the $\gamma$-$\gamma$ coincidence data were used to built the level scheme above the isomer up to $\sim$2~MeV excitation energy. The feeding of the 11/2$^{-}$ isomers, which originate from the odd proton occuping the h$_{11/2}$ orbital, was found in all three experiments to be very similar and it is compared to the feeding determined for the ground states of $^{191}$Ir, $^{193}$Ir and $^{197}$Au. \noindent This work was performed under the auspices of the U.S. Department of Energy by the University of California, Los Alamos National Laboratory under contract No. W-7405-ENG-36 and Lawrence Livermore National Laboratory under contract No. W-7405-ENG-48.