Microscopic calculations of fission barriers and critical angular momenta for excited heavy nuclear systems
- Ludwig Maximilian Univ., Munich (Germany)
In this paper, an extended version of Strutinsky's macro-microscopic method is used to calculate effective potential energies for rotating, excited heavy compound nuclei undergoing fission. Nuclear deformation is parameterized in terms of Lawrence's family of shapes. A two-center single-particle potential corresponding to these shapes is employed, with BCS pairing added. Statistical excitation is introduced by temperature-dependent occupation of (quasi-) particle energy levels. We calculate shell corrections to the energy, the free energy and the entropy as functions of deformation and temperature. The associated average quantities are derived from a temperature-dependent liquid drop model. The resulting static deformation energy is augmented by the rotational energy to yield the isothermal effective potential energy as a function of deformation, temperature and angular momentum. Moments of inertia are obtained from the adiabatic cranking model with temperature-dependent pairing included. We have also calculated the effective potential for constant entropy rather than constant temperature. Although this isentropic process physically is more appropriate than the isothermal process, it has not been treated before. For the same amount of excitation energy in the spherical state of the compound nucleus, the isentropic barriers turn out higher than the isothermal ones. For both processes we have extracted the critical angular momentum (defined as the one for which the barrier approximately vanishes) as a function of excitation. FInally, our model is applied to the super-heavy nuclei 270110, 278110, 298114, 292118 and 322128, which have been tried to form in krypton and argon induced heavy ion reactions.
- Research Organization:
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- USDOE Office of High Energy and Nuclear Physics; Deutsche Forschungsgemeinschaft (Germany)
- Contributing Organization:
- Ludwig Maximilian Univ., Munich (Germany)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 1076530
- Report Number(s):
- LBL-11522
- Journal Information:
- Nuclear Physics. A, Vol. 355, Issue 1; ISSN 0375-9474
- Publisher:
- Elsevier
- Country of Publication:
- United States
- Language:
- English
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