Fusion, fission, alpha emission and superheavy element formation and decay within a generalized liquid drop model

Abstract : New observed phenomena like cluster emission, cold and asymmetric fission of 252Cf, nuclear molecule formation in 24Mg, asymmetric fission of intermediate mass nuclei, quasi-fission of heavy dinuclear systems and alpha emission of superheavy nuclei have renewed interest in investigating the fusion-like fission valley which leads rapidly from a quasi-spherical nucleus to quasi-molecular shapes with deep necks and to two touching quasi-spherical fragments. Furthermore, the rotational super and hyperdeformed states as well as the very heavy and superheavy elements are and will be formed in the entrance channel of heavy-ion collisions for which the initial configuration is two close quasi-spherical nuclei. The balance between the repulsive Coulomb forces and attractive surface tension forces alone leads in this quasi-molecular shape valley to a potential barrier with an unrealistic Coulomb peak. A proximity energy term must be added to the usual development of the liquid drop model energy to smoothly describe the transition from one-body shapes to two-body compact shapes. This term takes into account the finite-range effects of the nuclear forces in the crevice between the nascent future fragments or the gap between the incoming nuclei. As a consequence we have developed a particular version of the liquid drop model taking into account both the nuclear proximity energy, the mass and charge asymmetry, the rotational energy, the shell and pairing effects and the temperature. A specific quasi-molecular shape sequence derived from elliptic lemniscatoids has been defined to describe within this generalized liquid drop model the entrance channel of nuclear reactions and also the peculiar decay channel through compact and creviced shapes. In this deformation valley and within this GLDM the calculated l-dependent fission and fusion barriers, alpha and cluster radioactivity half-lives and double-humped barriers and half-lives of actinides are in agreement with the available experimental data [1-4]. In this particular deformation valley, double-humped potential barriers begin to appear even macroscopically for heavy nuclei due to the influence of the proximity forces and quasi-molecular rotational isomeric states are formed at intermediate angular momentum during the fusion process of light or medium mass nuclei. [1] G. Royer, Nucl. Phys. A 848, 279 (2010). [2] G. Royer, J. Gaudillot, Phys. Rev. C 84, 044602 (2011). [3] G. Royer, M. Jaffré, D. Moreau, Phys. Rev. C 86, 044326 (2012). [4] X.J. Bao, H.F. Zhang, G. Royer, J.Q. Li, Nucl. Phys. A 906, 1 (2013).
Type de document :
Communication dans un congrès
French-Japanese Symposium on Nuclear Structure Problems, Sep 2013, Paris, France
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  • HAL Id : in2p3-01151846, version 1

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Guy Royer. Fusion, fission, alpha emission and superheavy element formation and decay within a generalized liquid drop model. French-Japanese Symposium on Nuclear Structure Problems, Sep 2013, Paris, France. 〈in2p3-01151846〉

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