Elsevier

Nuclear Physics A

Volume 324, Issue 1, 23 July 1979, Pages 39-52
Nuclear Physics A

Decay times for second-chance fission of 239U studied by crystal blocking

https://doi.org/10.1016/0375-9474(79)90076-9Get rights and content

Abstract

Neutron-induced fission of 238U has been studied by the crystal-blocking technique for neutron energies just below and above the threshold for second-chance fission. In agreement with earlier measurements, in this energy range the lifetime for first-chance fission is found to be too short to have an observable effect on the blocking dips. Above the threshold, however, an appreciable filling-in of the dips is observed. The results are analyzed in terms of a two-component lifetime distribution and then indicate an average lifetime of a few fsec for second-chance fission at a neutron energy of En ≈ 7.2 MeV, in agreement with results from a simple calculation. It is shown that in this analysis it is important to take into account the anisotropy of the fission-fragment distribution and, in particular, the difference between the angular distributions for first- and second-chance fission.

References (18)

  • Yu.V. Melikov et al.

    Nucl. Phys.

    (1972)
  • J.U. Andersen et al.

    Nucl. Phys.

    (1975)
  • R.P. Sharma et al.

    Nucl. Phys.

    (1973)
  • S.A. Karamyan et al.

    Sov. J. Particles and Nuclei

    (1973)
  • W.M. Gibson

    Ann. Rev. Nucl. Sci.

    (1975)
  • W.M. Gibson et al.

    Phys. Rev. Lett.

    (1970)
  • V.V. Kamanin et al.

    Sov. J. Nucl. Phys.

    (1973)
  • J.U. Andersen et al.

    Phys. Rev. Lett.

    (1976)
  • J. U. Andersen, A. S. Jensen, K. Jørgensen, E. Lægsgaard, K. O. Nielsen, J. S. Forster, I. V. Mitchell, D. Ward, W. M....
There are more references available in the full text version of this article.

Cited by (4)

Permanent address: Institute of Nuclear Physics, Moscow State University, Moscow, USSR.

View full text