The neutron-rich nuclei ${}^{109,111}\mathrm{Pd}$ have been produced as fission fragments following the fusion reactions ${}^{28,30}\mathrm{Si}+{}^{176}\mathrm{Yb}$ at 145 MeV and studied with the EUROGAM2 array. Two signature branches of a new band built on the $\nu h_{11/2}$ orbital have been identified in ${}^{109}\mathrm{Pd}$ and the favored signature of the $\nu h_{11/2}$ band has been observed for the first time in ${}^{111}\mathrm{Pd}.$ The spectroscopic properties as well as the rotational behavior of these bands are characteristic of bands expected for a prolate nuclear shape in this mass region. The effect of blocking of the first $h_{11/2}$ quasineutron in the odd-$A$ Pd nuclei supports the interpretation of the first crossing in the yrast bands of ${}^{110,112}\mathrm{Pd}$ as due to a $\nu {(h}_{11/2}{)}^2$ pair.

• Received 12 February 1998

DOI:https://doi.org/10.1103/PhysRevC.58.1966