6533b852fe1ef96bd12aaaf2
RESEARCH PRODUCT
Excited states in neutron deficient even-even thorium isotopes (218?A?222)
E. HaneltB. SchwartzS. GlienkeW. BoninHartmut BackeM. DahlingerE. KankeleitDietrich Habssubject
PhysicsNuclear and High Energy PhysicsFissionExcited stateNeutronElectric dipole transitionAtomic physicsGround stateSpectroscopyIsotopes of thoriumExcitationdescription
The nuclei218, 220, 222Th were investigated by conversion electron andγ-ray spectroscopy after compound nucleus reactions of14N with209Bi and16, 18O with208Pb. The intenseγ-background from fission was suppressed by spectroscopy of conversion electrons andγ-rays in coincidence with the evaporation residues or theirα-decay. Level schemes were determined for218Th up toIπ=10+ and for220Th and222Th up toIπ=15−. The observed structure of218Th may be explained in the spherical shell model with residual interaction by two neutron excitation. ForN≧130 completely different level schemes are observed showing very intense, collective electric dipole transitions (B(E1)−10−2 W.u.) with energies of typically 200 keV. Interpretation in terms of stable octupole deformations of the ground state as well as in anα-cluster picture are discussed.
| year | journal | country | edition | language |
|---|---|---|---|---|
| 1985-03-01 | Zeitschrift f�r Physik A Atoms and Nuclei |