Nuclear Fission and Structure Studies with Gammasphere

The γ-rays emitted in the spontaneous fission of 252Cf has been studied with Gammasphere. The yields of correlated Mo-Ba pairs in binary fission with 0–10 neutron emission have been remesured with an uncompressed cube. The previous hot fission mode with 8–10 neutron emission seen in the Mo-B a split is found to be smaller than earlier results but still present. New 0n binary SF yields are reported. By gating on the light charged particles detected with ΔE-E detectors mounted inside the Gammasphere chamber and γ — γ coincidences with Gammasphere, the relative yields of correlated pairs in alpha ternary fission with zero to 6n emission are observed for the first time. Half-lives (T1/2) of 7 states which decay by delayed γ transitions were determined from γ — γ — γ coincidences. High spin states in neutron-rich 104,106Mo nuclei have been investigated. The known ground state band, one-phonon and two-phonon γ-vibrational bands and two-quasiparticle bands are extended to high-spin. The one- and two-phonon γ-bands have remarkably close in energies. Several new quasiparticle bands are observed in both nuclei. In addition to their triaxial shape and large deformation, both high j two quasi-proton and two quasi-neutron orbitals close to the Fermi surface provide the necessary conditions for chiral bands. Two pairs of bands in 106Mo are found to have all the characteristics of chiral doublets, the first such in an even-even nucleus.