Pre- and post-scission neutron multiplicities in reaction at 108 MeVL.M. Pant1, A. Saxena1, R.G. Thomas1, D.C. Biswas1 and R.K. Choudhury2
1 Nuclear Physics Division, Bhabha Atomic Research Centre, Mumbai 400085, India
2 Institute of Physics, Bhubaneshwar, India
(Received: 15 March 2002 / Revised version: 23 August 2002 / Published online: 17 January 2003)
The pre- and post-scission neutron multiplicities have been determined from the fragment-neutron angular-correlation measurements in + reaction at bombarding energy of 108 MeV. The average pre-scission neutron multiplicity ( ) is significantly larger than that calculated on the basis of the statistical model. The excess in value is used to estimate the dynamical delay in the fusion-fission time scale for the compound system. For a level density parameter MeV -1 and = , the fusion-fission dynamical time was established to be 120 10 10 -21 s. We also observe that is higher for asymmetric mass splits as compared to symmetric mass splits. The enhancement in the for the asymmetric region could be due to strong variations in the fragment mass distribution at different stages in multiple chance fission at medium excitation energies.
25.70.Jj - Fusion and fusion-fission reactions.
© Società Italiana di Fisica, Springer-Verlag 2003