"Orientation degree of freedom as an essential collective coordinate in fission dynamics"
Alexandr Gegechkori, Omsk State University, Russia
(id #105)
Seminar: NoPoster: Yes
Invited talk: No
Despite the fact that the orientation degree of freedom (K state), which is the angular moment about the elongation axis, is used in transition state theory to calculate fission fragment angular distribution, it has been omitted in most dynamical studies of fission process except for several recent publications [1-4].
Lestone [1, 4] pointed out that the inclusion of K state is necessary for the correct fission width calculations in both statistical model and Langevin dynamics. Lestone also proposed an overdamped Langevin equation for K coordinate.
It was shown in [5] that both statistical saddle-point and scission-point transition state models fail to describe the large variety of experimental data regarding anisotropies of fission fragment angular distributions. This highlights the necessity of dynamical calculation of the above mentioned quantity and hence the dynamical treatment of the orientation degree of freedom.
We have generalized the Lestone's approach to the case of three shape degrees of freedom introduced on the basis of {c, h, α}-parametrization, thus implementing a four-dimensional dynamical model. Calculations have shown that the inclusion of orientation degree of freedom leads to the increase in the mean fission time and the decrease in the stationary fission rate. The increase in the mean fission time is about 1.5 times for 210 Po. This model was also applied to calculate fission fragment angular distributions and anisotropies of angular distributions in several fusion-fission reactions with heavy ions in the wide range of projectile's energy. This calculations have demonstrated that treating the orientation degree of freedom in the framework of Langevin dynamics yields results that are in reasonable agreement with the experimental data. The impact of dynamical model dimensionality on the results of fission fragment angular
distributions calculation is also discussed.
[1] J. P. Lestone and S. G. McCalla, Phys. Rev. C 79, 044611 (2009).
[2] D. O. Eremenko, V. A. Drozdov, M. H. Eslamizadex, O. V. Fotina, S. Y. Platonov, and O. A.
Yuminov, Phys. At. Nucl. 69, 1423 (2006).
[3] A. V. Karpov, R. M. Hiryanov, A. V. Sagdeev, and G. D. Adeev, J. Phys. G: Nucl. Part. Phys.
34, 255 (2007).
[4] J. P. Lestone, Phys. Rev. C 59, 1540 (1999).
[5] R. Freifelder, M. Prakash, and J. M. Alexander, Phys. Rep. 133, 315 (1986).
Lestone [1, 4] pointed out that the inclusion of K state is necessary for the correct fission width calculations in both statistical model and Langevin dynamics. Lestone also proposed an overdamped Langevin equation for K coordinate.
It was shown in [5] that both statistical saddle-point and scission-point transition state models fail to describe the large variety of experimental data regarding anisotropies of fission fragment angular distributions. This highlights the necessity of dynamical calculation of the above mentioned quantity and hence the dynamical treatment of the orientation degree of freedom.
We have generalized the Lestone's approach to the case of three shape degrees of freedom introduced on the basis of {c, h, α}-parametrization, thus implementing a four-dimensional dynamical model. Calculations have shown that the inclusion of orientation degree of freedom leads to the increase in the mean fission time and the decrease in the stationary fission rate. The increase in the mean fission time is about 1.5 times for 210 Po. This model was also applied to calculate fission fragment angular distributions and anisotropies of angular distributions in several fusion-fission reactions with heavy ions in the wide range of projectile's energy. This calculations have demonstrated that treating the orientation degree of freedom in the framework of Langevin dynamics yields results that are in reasonable agreement with the experimental data. The impact of dynamical model dimensionality on the results of fission fragment angular
distributions calculation is also discussed.
[1] J. P. Lestone and S. G. McCalla, Phys. Rev. C 79, 044611 (2009).
[2] D. O. Eremenko, V. A. Drozdov, M. H. Eslamizadex, O. V. Fotina, S. Y. Platonov, and O. A.
Yuminov, Phys. At. Nucl. 69, 1423 (2006).
[3] A. V. Karpov, R. M. Hiryanov, A. V. Sagdeev, and G. D. Adeev, J. Phys. G: Nucl. Part. Phys.
34, 255 (2007).
[4] J. P. Lestone, Phys. Rev. C 59, 1540 (1999).
[5] R. Freifelder, M. Prakash, and J. M. Alexander, Phys. Rep. 133, 315 (1986).
