International Workshop on

______________________________________________________________________________________

FUSION DYNAMICS

AT THE EXTREMES

Dubna , Russia 25-27 May 2000

Editors

Yu.Ts. Oganessian & V.I. Zagrebaev

Flerov Laboratory of Nuclear Reactions,

Joint Institute for Nuclear Research, Dubna, Russia

World Scientific Singapore · New Jersey · London · Hong Kong

PREFACE

The aim of the Workshop was to bring together theoreticians and experimentalists who work in the field of near-barrier nuclear fusion, synthesis and investigation of properties of superheavy elements (SHE). The progress made lately by the experimentalists who have very closely approached the possibility of testing the hypothesis of the existence of “islands of stability” in the region of superheavy and exclusively stable by the nuclear standards nuclei, met with a similar activity of theoreticians. It turned out that both communities have accumulated a large arsenal of ideas and solutions after a long period of evolution and acquiring new knowledge, when production of individual atoms of new elements was taking years and years.

Even without clear understanding of complex fusion-fission dynamics in extremely heavy nuclear systems the experimentalists took the risk of departing from traditional methods of synthesis of new elements and made a number of attempts to advent into unexplored areas, which had earlier been regarded as non-promising and doubtful. They decided to fortify this intervention by setting up new experiments devoted to the study of nuclear fusion-fission reactions, choosing as objects of investigation such combinations, which potentially lead to the synthesis of SHE.

On the other hand, theoretical models of the atomic nucleus and, in particular, methods of calculation of masses and decay properties of nuclei far from the stability line have progressed substantially, interalia in connection with the development of physics of radioactive beams and prospects offered by the acceleration of neutron-rich fission fragments in the near future. Application of these achievements to superheavy nuclei leads to several possibilities in predicting the SHE properties depending on the used model of the nuclear matter structure. That is why we invited to our Seminar all leading physicists, theoreticians and experimentalists, who work in the field of physics of SHE. The majority of them, whose names you can see in the list of speakers, accepted our invitation and came to Dubna.

In discussing the problems of near-barrier fusion of complex nuclei, the competition between different reaction channels and their coupling, it was interesting to understand what new information can be extracted in the case of using radioactive ion beams (RIB), in particular beams of neutron-rich nuclei. That is why a large number of contributions were devoted to the reactions induced by radioactive nuclei, that is to the line in the investigations which will be developing in the future in connection with the realization of big projects on the creation of facilities for the production of high-intensity RIBs.

We express gratitude to all our guests and wish them further fruitful work.

Yu.Ts. Oganessian

V.I. Zagrebaev

C O N T E N T S

Preface	v
Aspects of Fusion, Fission and Cluster Radioactivity W. Greiner	1
Current Problems of Superheavy Nuclei I. Muntian, Z. Patyk and A. Sobiczewski	21
Structure of Super-Heavy Nuclei in Mean-Field Models K. Rutz, T. Bürvenich, M. Bender, P.-G. Reinhard, J.A. Maruhn and W. Greiner	31
Superheavy Nucley in Deformed Mean-Field Calculations T. Bürvenich, J.A. Maruhn, W. Greiner, P.-G. Reinhard	39
Extrapolation of Mean-Field Models to Superheavy Nuclei M. Bender	51
The Synthesis of Superheavy Nuclei in the ^48Ca+^244Pu Reaction Yu.Ts. Oganessian, V.K. Utyonkov, Yu.V. Lobanov, F.Sh. Abdullin, A.N. Polyakov, I.V. Shirokovsky, Yu.S. Tsyganov, G.G. Gulbekian, S.L. Bogomolov, B.N. Gikal, A.N. Mezentsev, S. Iliev, V.G. Subbotin, A.M. Sukhov, O.V. Ivanov, G.V. Buklanov, K. Subotic, M.G. Itkis, K.J. Moody, J.F. Wild, N.J. Stoyer, M.A. Stoyer, R.W. Lougheed	65
Experiments on the Synthesis of Superheavy Elements with ^48Ca Beams at the Separator VASSILISSA. Yu.Ts. Oganessian, A.V. Yeremin, A.V. Belozerov, M.L. Chelnokov, V.I. Chepigin, V.A. Gorshkov, A.P. Kabachenko, S.P. Korotkov, O.N. Malyshev, A.G.Popeko, J.Roháč, R.N. Sagaidak, S.Hofmann, G.Műnzenberg, M. Veselsky, S. Saro, N. Iwasa, K. Morita, G.Giardina	81
Fusion-Fission of Superheavy Nuclei at Low Excitation Energies M. G. Itkis, Yu. Ts. Oganessian, A. A. Bogatchev, I. M. Itkis, M. Jandel, J. Kliman, G. N. Knjajeva, N. A. Kondratiev, I. V. Korzyukov, E. M. Kozulin, L. Krupa, I. V. Pokrovski, V. A. Ponomarenko, E. V. Prokhorova, A. Ya. Rusanov, V. M. Voskresenski, F. Hanappe, B. Benoit, T. Materna, N. Rowley, L. Stuttge, G. Giardina, K. J. Moody	93
Survival Probability for Heavy Compound Nuclei M. Ohta	110
Theoretical Estimation of Evaporation Residue Cross Section for Production of Superheavy Elements in the Framework of Fluctuation-dissipation Model Y. Aritomo, T. Wada, M. Ohta and Y. Abe	123
Fusion Probability and Survivability in the Reactions Leading to the Production of Heavy and Superheavy Nuclei R. N. Sagaidak, V. I. Chepigin, M. G. Itkis, A. P. kabachenko, O. N. Malyshev, Yu. Ts. Oganessian, A. G. Popeko, J. Roháč, A. V. Yeremin	135
Decay Properties of Superheavy Elements (Theory and Experiment) Yu. Ts. Oganessian	148
Semi-Bubbles and Bubbles: a New Kind of Superheavy Nuclei K. Dietrich	155
Reaction Theory for Synthesis of the Superheavy Elements Y. Abe	162
The Dinuclear System Concept for the Complete Fusion Process V.V. Volkov	174
Calculation of Formation and Decay of Heavy Compound Nuclei E.A. Cherepanov	186
Formation of Superheavy Elements R. Smolańczuk	200
Production of Superheavy Elements in Heavy Ion Reactions V.Yu. Denisov	203
Fusion-Fission Dynamics of the Synthesis of Superheavy Nuclei V.I. Zagrebaev	215
Fusion and Alpha Emission within a Liquid Drop Model and Heaviest Element Formation and Decay G. Royer, R.A. Gherghescu	232
On Scission Configuration in Ternary Fission V. Kartavenko, A. Săndulescu, W. Greiner	243
Fusion of Weakly Bound Stable Nuclei - What Can We Learn? M. Dasgupta, A.C. Berriman, R. D. Butt, D.J. Hinde, C.R. Morton, J.O. Newton, R. M. Anjos, P.R.S. Gomes, S.B. Moraes, N. Carlin, A. Szanto de Toledo	254
Spin and Excitation Energy Dependence of Fission Survival: a New Probe for the Fusion Fission Dynamics S. K. Hui, A. K. Ganguly, C. R. Bhuinya, N. Madhavan, J. J. Das, P. Sugathan, S. Muralithar, L. T. Baby, V. Tripathi, A. K. Sinha, A.M. Vinodkumar, D.O. Kataria, N.V.S.V. Prasad, P.V. Madhusudhana Rao, Raghuvir Singh	264
Sub-Barrier Fusion and Multi Nucleon Transfer in Medium-Heavy Nuclei F.Scarlassara, S.Beghini, G.Montagnoli, G.F.Segato, L.Corradi, A.M.Stefanini, A.M.Vinodkumar	274
Interplay between Fusion, Transfer and Breakup Reactions at Near-Barrier Energies P. R. S. Gomes, J. Lubian, S. B. Moraes , J. J. S. Santos, A.M.M. Maciel, R. M. Anjos, I. Padrón, C. Muri, R.Liguori Neto, N.Added	284
Mechanisms of Sub-Barrier Fusion Enhancement N. Rowley	296
Near-Barrier Fusion of ^6He + ^209Bi Yu. Penionzhkevich, Yu.A. Muzychka, S.M. Lukyanov, R. Kalpakchieva, N.K. Skobelev, V.P. Perelygin, L.V. Mikhailov, Yu.G. Sobolev, Z. Dlouhy, Ya. Mrazek, J. Vincour, N.O. Poroshin, F. Oliveira de Santos, L. Kostov, N.A. Demekhina, F. Negoita	308
Transfer, Breakup, and Fusion Reactions of ^6He with ^209Bi near the Coulomb Barrier J.J. Kolata	318
Study of Sub-Barrier and Near-Barrier Fusion of Halo Nuclei N.Alamanos, J.L. Sida, V. Lapoux, A. Pakou, M. Trotta	327
Sub-Barrier Fusion of Drip-Line Nuclei K. Hagino, A. Vitturi	335
Fusion of Light Weakly Bound Nuclei A. Szanto de Toledo, E. Alonso, N. Carlin, R.J. Fujii, M.M. de Moura, M.G. Munhoz, F.A. Souza, A.A.P Suaide, E.M. Szanto, J. Takahashi	347
List of Speakers	359
Author Index	362