Fission Barriers of Compound Heavy Nuclei and Pairing Reentrance Phenomenon in Heated Rotating Nuclei
W. Nazarewicz (University of Tennessee and ORNL, USA)
| What |
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| When |
2009-05-15 from 11:00 am à 12:00 pm |
| Where | salle des séminaires du GANIL |
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In this presentation, I shall address two questions related to the physics of heated nuclei. The first part will be devoted to the dependence of fission barriers on the excitation energy for the compound superheavy nuclei synthesized in heavy-ion fusion reactions. The relationship between isothermal and isentropic descriptions has been quantified through self-consistent calculations. For nuclei around 278-112 produced in "cold fusion" reactions, we predict a more rapid decrease of fission barriers with excitation energy as compared to the nuclei around 292-114 synthesized in "hot fusion" experiments. This has been explained in terms of the difference between the ground-state and saddle-point temperatures. The effect of the particle gas has been found to be negligible in the range of temperatures studied.
In the second part, I will talk about the rotational motion of heated nuclei described within the Shell Model Monte Carlo (SMMC) approach. The reentrance of pairing correlations with temperature, a specific feature of the final system, has been predicted at high rotational frequencies. In other systems, such partial order phenomena manifest themselves in successive phase transitions. One of the signatures of the reentrance of the partial order is the anomalous specific-heat behavior, which is predicted by SMMC.
