Spectroscopy of reflection-asymmetric nuclei using multinucleon transfer reactions

The heavy-ion collisions of {sup 56}Fe + {sup 232}Th, {sup 86}Kr + {sup 232}Th and {sup 136Xe} + {sup 232}Th with beam energies 15--20% above the Coulomb barrier were used to populate nuclei in the light-actinide region. Yield distributions of the binary reaction products stopped in thick targets were obtained by measuring {gamma}-{gamma} coincidence intensities. The {sup 136}Xe + {sup 232}Th reaction was repeated at Lawrence Berkeley National Laboratory using a recent implementation of the GAMMASPHERE array. Many interesting discoveries concerning the high-spin structure of octupole-deformed light-actinide nuclei have been made

Cluster Interpretation of Properties of Alternating Parity Bands in Heavy Nuclei

The properties of the states of the alternating parity bands in actinides, Ba, Ce and Nd isotopes are analyzed within a cluster model. The model is based on the assumption that cluster type shapes are produced by the collective motion of the nuclear system in the mass asymmetry coordinate. The calculated spin dependences of the parity splitting and of the electric multipole transition moments are in agreement with the experimental data.Comment: 29 pages, 10 figure

Identification of yrast states in 187Pb

g -ray spectroscopy of the high-spin states of the neutron-deficient nucleus 187Pb has been conducted with the 155Gd(36Ar,4n) reaction. A cascade of three transitions was deduced from g -g coincidence data gated by detection of recoiling evaporation residues in a gas-filled recoil separator. In an earlier, separate experiment, two of these g rays were positively identified with 187Pb by recoil-g coincidence measurements with a high-resolution, recoil mass spectrometer. From comparison with similar sequences in heavier odd-A lead isotopes, the cascade in 187Pb is associated with the sequence of three E2 transitions from the yrast 25/2 + level to a low-lying 13/2 + isomer. The variation of excitation energy with mass number of the levels concerned suggests that their structure can be associated with weak coupling of an odd i13/2 neutron to states in the spherical well. However, the possibility that they are influenced by mixing with states in the prolate-deformed well cannot be discounted

High-spin spectroscopy of octupole structures in radon and radium isotopes using multinucleon transfer reactions

SIGLEAvailable from British Library Document Supply Centre-DSC:DXN008453 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Electromagnetic transitions and α\alpha decay of the 223^{223}Pa nucleus

Actinides with N~132 present the best explored region of pear shape nuclei. Still almost no spectroscopic information is available for the heaviest elements, Z=91–98, which are predicted to be octupole instable. The lack of data for the latter nuclei results from the high fission probability encountered in the heavy-ion reactions used to populate them. In order to overcome this handicap, an alpha -decay tagging technique was used to identify gamma rays in 223Pa produced through the 208Pb(19F,4n) reaction. A new value of 4.9(4) ms for the half-life of 223Pa was obtained as a by-produc