Ядерна фізика та енергетика Nuclear Physics and Atomic Energy   ISSN: 1818-331X (Print), 2074-0565 (Online)   Publisher: Institute for Nuclear Research of the National Academy of Sciences of Ukraine   Languages: Ukrainian, English   Periodicity: 4 times per year   Open access peer reviewed journal

Full text (en)

V. A. Rubchenya¹, I. Tsekhanovich<sup>2

1</sup>V. G. Khlopin Radium Institute, St. Petersburg, Russia
²Institut Laue-Langevin, Grenoble, France

Abstract: The multimodal approach to fission and the macroscopic-microscopic method for the calculations of charge distribution parameters for isobaric chains have been used to analyze fission product yields. In order to describe the peculiarities of fragment mass curve at very asymmetric mass split, the two narrow fission modes related to the magic numbers Z = 28 and N = 50 were introduced. The reliability of the model's predicting power was demonstrated by the agreement between calculated and experimental data on the thermal-neutron-induced fission of actinides. It was found that weight of the fission modes related to the spherical doubly-magic clusters (¹³²Sn or ⁷⁸Ni) depends on the neutron-to-proton ratio of a compound system.

1. Strutinsky V. M. Influence of Nucleon Shells on the Energy of a Nucleus. Soviet Journal of Nuclear Physics 3 (1966) 449.

2. Strutinsky V. M. Shell effects in nuclear masses and deformation energies. Nuclear Physics A 95 (1967) 420. https://doi.org/10.1016/0375-9474(67)90510-6

3. Strutinsky V. M. "Shells" in deformed nuclei. Nuclear Physics A 122 (1968) 1. https://doi.org/10.1016/0375-9474(68)90699-4

4. Pashkevich V. V. On the asymmetric deformation of fissioning nuclei. Nuclear Physics A 169 (1971) 275. https://doi.org/10.1016/0375-9474(71)90884-0

5. Brack M., Jens Damgaard, Jensen A. S. et al. Funny Hills: The Shell-Correction Approach to Nuclear Shell Effects and Its Applications to the Fission Process. Reviews of Modern Physics 44 (1972) 320. https://doi.org/10.1103/RevModPhys.44.320

6. Rubchenya V. A. Fragment shell structure effect in fission. Soviet Journal of Nuclear Physics 9 (1969) 697.

7. Wilkins B. D., Steinberg E. P., Chasman R. R. Scission-point model of nuclear fission based on deformed-shell effects. Physical Review C 14 (1976) 1832. https://doi.org/10.1103/PhysRevC.14.1832

8. Moll E., Schrader H., Siegert G. et al. Aufbau und Arbeitsweise des Spaltprodukt Massenseparators Lohengrin am Hochfluss-Reaktor in Grenoble. Kerntechnik 19 (1977) 374.

9. Rochman D., Tsekhanovich I., Gönnenwein F. et al. Super-asymmetric fission in the ²⁴⁵Cm(n_th, f) reaction at the Lohengrin fission-fragment mass separator. Nuclear Physics A 735 (2004) 3. https://doi.org/10.1016/j.nuclphysa.2004.01.121

10. Huhta M., Dendooven P., Honkanen A. et al. Superasymmetric fission at intermediate energy and production of neutron-rich nuclei with A < 80. Physics Letters B 405 (1997) 230. https://doi.org/10.1016/S0370-2693(97)00610-2

11. Hankonen S., Dendooven P., Huikari J. et al. Production of neutron-rich nuclei with A < 80 in superasymmetric fission at IGISOL. Acta Physica Polonica B 30 (1999) 677.

12. Rubchenya V. A., Äystö J., Dendooven P. et al. Fission product yields at intermediate energy. Nuclear Fission and Fission-Product Spectroscopy: Proc. of Second International Workshop. Ed. by G. Fioni et al., CP447, The American Institute of Physics (1998) p. 453.

13. Rubchenya V. A., Alexandrov A. A., Alkhazov I. D. et al. Fission modes in ²³⁸U+d reaction at intermediate energy. Fission and Properties of Neutron-Rich Nuclei: Proc. of the Second International Conference, St. Andrews, Scotland, June 28 - July 2, 1999. Ed. by J. H. Hamilton, W. R. Philips, H. K. Carter (Singapore: World Scientific, 2000) p. 484.

14. Rubchenya V. A., Trzaska W. H., Itkis I. M. et al. Fission dynamics in the proton induced fission of heavy nuclei. Nuclear Physics A 734 (2004) 253. https://doi.org/10.1016/S0375-9474(04)90288-6

15. Tsekhanovich I., Varapai N., Rubchenya V. A. et al. Fission-product formation in the thermal-neutron-induced fission of odd Cm isotopes. Physical Review C 70 (2004) 044610. https://doi.org/10.1103/PhysRevC.70.044610

16. Rubchenya V. A., Äystö J. Theoretical predictions for the neutron rich fission product yields. Study for RNB projects. EURISOL Research Project (2003) unpublished. http://ganil.fr/eurisol/

17. Brosa U., Grossmann S., Müller A. Nuclear scission. Physics Report 197 (1990) 167. https://doi.org/10.1016/0370-1573(90)90114-H

18. Rubchenya V. A., Äystö J. Production of neutron rich isotopes in fission. A study for RNB facilities. Nuclear Physics A 701 (2002) 127. https://doi.org/10.1016/S0375-9474(01)01560-3

19. Nifenecker H. A dynamical treatment of isobaric widths in fission: An example of frozen quantal fluctuations. J. Physique Lett. 41 (1980) 47. https://doi.org/10.1051/jphyslet:0198000410304700

20. Cwiok S., Dudek J., Nazarewicz W. et al. Single-particle energies, wave functions, quadrupole moments and g-factors in an axially deformed Woods-Saxon potential with applications to the two-centre-type nuclear problems. Computer Physics Communications 46 (1987) 379. https://doi.org/10.1016/0010-4655(87)90093-2

21. Hernandez E. S., Myers W. D., Randrup J., Remaud B. Quantal dynamics of charge equilibration in damped nuclear collisions. Nuclear Physics A 361 (1981) 483. https://doi.org/10.1016/0375-9474(81)90648-5

22. Bocquet J. P., Brissot R. Mass, energy and nuclear charge distribution of fission fragments. Nuclear Physics A 502 (1989) 213. https://doi.org/10.1016/0375-9474(89)90663-5

23. Tsekhanovich I., Denschlag H. -O., Davi M. et al. Mass and charge distributions in the very asymmetric mass region of the neutron induced fission of ²³⁸Np. Nuclear Physics A 688 (2001) 633. https://doi.org/10.1016/S0375-9474(00)00586-8

24. Rubchenya V. A. Superasymmetric fission. Fission Dynamics of Atomic Clusters and Nuclei. Proc. of the International Workshop, Luso, Portugal, 15-19 May 2000. Ed. by J. da Providencia et al. (Singapore: World Scientific, 2001) p. 221. https://doi.org/10.1142/9789812811127_0021