Particle-phonon interactions in Cf248 and Cf249

The extent of particle-photon mixing in Cf248 and Cf249 has been determined using the Cf249(d, t) and Cf249(d, d ) reactions. K=2- bands were identified at 593 and 1477 keV in Cf248. Since the only K=2- neutron two quasiparticle configuration expected below 2 MeV in Cf248 is {92-[734]; 52+[622]}2-, the second K=2- band is considered to be predominantly of phonon character. In Cf249 a K=52+ band at 145 keV, known from decay scheme studies, receives a measurable population in the (d, d ) reaction. The phonon admixture in the 52+ state which results from the {92-[734]- 2- phonon} configuration was determined to be (29±5)%. The collective admixture in the 52+ state was also calculated from an octupole particle-hole interaction and was found to be 35%, in good agreement with the experimental value. The anomalously low energy of the 52+ state could not be entirely reproduced by this calculation. NUCLEAR REACTIONS Cf249(d, d ), Ed=15 MeV; Cf249(d, t), Ed=12 MeV; measured (,). Cf248, Cf249 deduced levels, J, extracted phonon contributions. Enriched target. Calculated particle-phonon mixing.