In bombardments of 206,207,208Pb with 34S and 206Pb with 36S, we identified a new spontaneously fissioning isotope 238Cf with T sf ≈ T 1 2 = 21 ± 2 ms and obtained evidence of the production of a new isotope 237Cf with T 1 2 = 2.1 ± 0.3 s . The spontaneous-fission (SF) decay mode was established for 240Cf; its SF branch was estimated to be bsf ∼ 2 × 10−2. We measured also bsf ⩽ 1.4 × 10−4 for 242Cf and estimated bsf ∼ 10−1 for 237Cf. The production cross sections of 238Cf in the 206,207,208 Pb + 34 S reactions were measured to be in the range of 0.3 to 1.1 nb. Finally, we probed the influence of the neutron excess in the N = 20 projectile 36S on cross sections of fusion-evaporation reactions occurring on lead targets.
