MASS DEPENDENCE OF FRAGMENT ANISOTROPY IN THE FISSION OF B-11-237 ANDO-16+BI-209 SYSTEMS(NP)

Measurements were carried out on mass, energy correlations of fission fragments for the systems of B-11+Np-237 at E(lab)=76 MeV and O-16+Bi- 209 at E(lab)=100 MeV at forward and perpendicular angles of emission with respect to the beam direction. The fragment anisotropy averaged o ver all fragment masses matches well for both the systems with the sta ndard saddle point statistical model calculations. Variation of the an gular anisotropy and total kinetic energy of fragments were studied as a function of the mass:of the fragment pair. For the B-11+Np-237 syst em, the fragment anisotropy is seen to be nearly independent of the fr agment mass, whereas for the O-16+Bi-209 system, the anisotropy is see n to decrease with increasing fragment mass asymmetry. The results are discussed on the basis of the statistical model of fragment angular d istributions and mass division in the fission process.