Search for superheavy nuclei with lifetimes longer than 2 ps

The reaction 469 MeV 86 Kr + 208 Pb was used to search for superheavy elements which decay at rest by fission. The technique searches with equal sensitivity over a lifetime range from 2 ps (the stopping time of the fused system) to many hours and thus covers a broad spectrum of lifetimes not yet examined for superheavy element production. No evidence for such formation was found; the upper limit on the cross section is 1.5 μb.