New superheavy element isotopes: Pu242(Ca48,5n)128514

The new, neutron-deficient, superheavy element isotope 128514 was produced in Ca48 irradiations of Pu242 targets at a center-of-target beam energy of 256 MeV (E*=50MeV). The α decay of 128514 was followed by the sequential α decay of four daughter nuclides, Cn281, Ds277, Hs273, and Sg269. Rf265 was observed to decay by spontaneous fission. The measured α-decay Q values were compared with those from a macroscopic-microscopic nuclear mass model to give insight into superheavy element shell effects. The Pu242(Ca48,5n)128514 cross section was 0.6-0.5+0.9pb. © 2010 The American Physical Society.