Spontaneous Fission of Light Californium Isotopes Produced in the (sup 206),(sup 207),(sup 208) Pb + (sup 34),(sup 36) S Reactions; New Nuclide (sup 238) Cf

摘要

In bombardments of (sup 206) Pb, (sup 207) Pb, (sup 208) Pb with (sup 34) S and (sup 206) Pb with (sup 36) S, we identified a new spontaneously fissioning isotope (sup 238) Cf with T(sub sf) (approx) T(sub 1/2) = 21 (+-) ms and obtained evidence of the production of a new isotope (sup 237) Cf with T(sub 1/2) = 2,1 (+-) 0,3 s. We measured spontaneous fission branches for (sup 242) Cf and (sup 240) Cf to be b(sub sf) (<=) 1,4 x 10(sup -4) and b(sub sf) (approx) 2 x 10(sup -2), respectively. For (sup 237) Cf, we estimated b(sub sf) to be (approx) 10(sup -1). The measured production cross sections of (sup 238) Cf in the (sup 206),(sup 207),(sup 208) Pb + (sup 34) S reactions are in the range of 0,3 to 1,1 nb. We probed also the influence of the neutron excess in the N = 20 projectile (sup 36) S on cross sections of fusion-evaporation fusion-evaporation reactions occurring on lead targets. 19 refs., 3 figs., 2 tabs. (Atomindex citation 26:013300)