Abstract
We have measured the mass and kinetic-energy distributions of fragments from the spontaneous fission of . The was produced via the N,4n) reaction with a production cross section of 100 nb using 81-MeV projectiles. The kinetic energies and times of the alpha particles and coincident fission fragments were measured using our rotating wheel system. From these data the half-life, mass, and kinetic-energy distributions were derived. The total kinetic-energy (TKE) distribution appears to consist of a single component with a most probable pre-neutron-emission TKE of 215±3 MeV. The mass distribution is predominantly symmetric with a full width at half maximum of about 20 mass numbers. These results are consistent with trends observed for other trans-berkelium spontaneously fissioning isotopes. We determined the half-life to be 6.14±0.36 s by measuring its alpha decay and the observed spontaneous fission half-life was consistent with that value. An energy of 8.439±0.010 MeV was measured for the main alpha transition of . We measured a spontaneous fission to alpha-decay ratio of 0.25±0.03 which results in a partial half-life for spontaneous fission of 31±4 s, if there are no other appreciable modes of decay.
- Received 1 June 1992
DOI:https://doi.org/10.1103/PhysRevC.46.1873
©1992 American Physical Society