Zeitschrift für Physik A Hadrons and Nuclei

, Volume 351, Issue 3, pp 281–288 | Cite as

Parity nonconservation and Brosa modes in nuclear fission

  • U. Graf
  • F. Gönnenwein
  • P. Geltenbort
  • K. Schreckenbach
Short Note


The parity nonconserving (PNC) asymmetry coefficient α for the angular distribution of fragment emission from binary fission of233U irradiated by polarized thermal neutrons has been measured. Complementary fragments were detected by a double ionization chamber with high resolving power. The experiment was carried out at the high flux reactor of the ILL, Grenoble. Integrated over all masses and energies of light fragments from asymmetric fission of234Uh, the PNC asymmetry coefficient is found to be α=(3.29±0.31) × 10−4.The positive sign of α indicates a preferential emission of light fragments parallel to the spin of neutrons inducing fission. Theory claims that PNC effects are sensitive to the properties of the fission barrier. On the other hand, one may wonder whether characteristics of eventual fragments are already specified at the barrier. The measurement of PNC asymmetries for distinct mass-energy ranges of fragments has been utilized to answer this question. Mass-energy distributions of fragments were analyzed along the lines of the Brosa model of fission as a superposition of individual modes. Within experimental uncertainty no mode dependence of asymmetric fission could be disclosed. The result is in keeping with the Brosa model where asymmetric modes bifurcate only once the standard fission barrier has been passed.


24.80.Dc 25.85.Ec 


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  1. 1.
    Danilyan, G.V., Vodennikov, B.D., Dronyaev, V.P., Novitskii, V.V., Pavlov, V.S., Borovlev, S.P.: JETP Lett.26 186 (1977)Google Scholar
  2. 2.
    Sushkov, O.P., Flambaum, V.V.: Sov. J. Nucl. Phys.33, 31 (1981)Google Scholar
  3. 3.
    Bunakov, V.E., Gudkov, V.P.: Nucl. Phys.A401, 93 (1983)Google Scholar
  4. 4.
    Petrov, G.A., Valskii, G.V., Petukhov, A.K., Alexandrovich, A.Ya., Pleva, Yu.S., Sokolov, V.E., Laptev, A.B., Scherbakov, O.A.: Nucl. Phys.A502, 297c (1989)Google Scholar
  5. 5.
    Bohr, A.: Proc. Int. Conf. Peaceful Uses Atomic Energy, Geneva 1955, United Nations, New York, 1956, Vol.II, p 51Google Scholar
  6. 6.
    Krappe, H.-J., Wille, U.: Nucl. Phys.A124, 641 (1969)Google Scholar
  7. 7.
    Brosa, U., Großmann, S., Müller, A.: Phys. Rep.197, 167 (1990)Google Scholar
  8. 8.
    Krupchitsky, P.A.: Fundamental Research with Polarized Slow Neutrons, Springer 1987Google Scholar
  9. 9.
    Geltenbort, P., Gönnenwein, F., Oed, A.: Radiat. Effects93, 57 (1986)Google Scholar
  10. 10.
    Knitter, H.-H., Hambsch, F.J., Budtz-Jørgensen, C., Theobald, J.P.: Z. f. Naturforsch.42a, 786 (1987)Google Scholar
  11. 11.
    Gönnenwein, F.: in The Nuclear Fission Process, C. Wagemans ed., CRC Press, USA, 1991, p 87Google Scholar
  12. 12.
    Vandenbosch, R., Huizenga, J.R.: Nuclear Fission, New York and London: Academic Press 1973Google Scholar
  13. 13.
    Itkis, M.G., Mulgin, S.I., Okolovich, V.N., Rusanov, A. Ya., Smirenkin, G.N.: Sov. J. Nucl. Phys.53, 238 (1991)Google Scholar
  14. 14.
    Gönnenwein, F., Belozerov, A.V., Beda, A.G., Burov, S.I., Danilyan, G.V., Martem'yanov, A.N., Pavlov, V.S., Shchenev, V.A., Bondarenko, L.N., Mostovoi Yu.A., Geltenbort, P., Last, J., Schreckenbach, K.: Nucl. Phys.A567, 303 (1994)Google Scholar
  15. 15.
    Alexandrovich, A.Ya., Gagarski, A.M., Krasnoschekova, I.A., Petrov, G.A., Petrova, V.I., Petukhov, A.K., Pleva, Yu. S., Geltenbort, P., Last, J., Schreckenbach, K.: Nucl. Phys.A567, 541 (1994)Google Scholar
  16. 16.
    Steiper, F., Frommhold, Th., Henkel, W., Jung, A., Kneissl, U., Stock, R.: Nucl. Phys.A563, 282 (1993)Google Scholar

Copyright information

© Springer-Verlag 1995

Authors and Affiliations

  • U. Graf
    • 1
  • F. Gönnenwein
    • 1
  • P. Geltenbort
    • 2
  • K. Schreckenbach
    • 3
  1. 1.Physikalisches InstitutUniversität TübingenTübingenGermany
  2. 2.Institut Laue-LangevinGrenobleFrance
  3. 3.Fakultät für PhysikTU MünchenGarchingGermany

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