Character of particle-hole excitations in γ-ray angular correlation and linear polarization measurements

Linear polarization and angular correlations of γ-rays depopulating excited states in the neutron-deficient nucleus 9444Ru50 have been measured, enabling firm spin-parity assignments for several excited states in this nucleus. The deduced multipolarities of strong transitions in the yrast structure were found to be mostly of stretched M1, E1, and E2 types and, in most cases, in agreement with previous tentative assignments. The deduced multipolarity of the 1869 keV and the connecting 257 and 1641 keV transitions indicates that the state at 6358 keV excitation energy has spin parity 12−1 rather than 12+3 as proposed in previous works. The presence of a 12−1 state is interpreted within the framework of large-scale shell-model calculations as a pure proton-hole state dominated by the π(p−11/2⊗g−59/2) and π(p−13/2⊗g−59/2) configurations. A new positive-parity state is observed at 6103 keV and is tentatively assigned as 12+2. The 14−1 state proposed earlier is reassigned as 13−4 and is interpreted as being dominated by neutron particle-hole core excitations. The strengths of several E1 transitions have been measured and are found to provide a signature of core-excited configurations.