A search was made for spontaneously fissioning superheavy elements in damped collisions of two uranium nuclei. Different techniques were applied covering the elements 108 to 118 and ≃ 126, and a half-life range from 1 ms to more than 1 yr. No evidence for superheavy elements was found at upper cross-section limits of ${10}^{-32\mathrm{}}$, ${10}^{-33\mathrm{}}$, and ${10}^{-35\mathrm{}}$ ${\mathrm{cm}}^2$ for half-lives from 1 to 100 ms, 100 ms to 1 d, and 1 d to 1 yr, respectively.

• Received 18 August 1980

DOI:https://doi.org/10.1103/PhysRevLett.45.1824