Schottky mass measurements of heavy neutron-rich nuclides in the element range $70\leZ \le79$ at the ESR

Storage-ring mass spectrometry was applied to neutron-rich Au-197 projectile fragments. Masses of Lu-181,Lu-183, Hf-185,Hf-186, Ta-187,Ta-188, W-191, and Re-192,Re-193 nuclei were measured for the first time. The uncertainty of previously known masses of W-189,W-190 and Os-195 nuclei was improved. Observed irregularities on the smooth two-neutron separation energies for Hf and W isotopes are linked to the collectivity phenomena in the corresponding nuclei.