CHARGE-DISTRIBUTION IN THE MASS REGION 128 134 IN LOW-ENERGY FISSION OF ACTINIDES

Fractional cumulative yields (FCY) of 128Sn, 131Sb, Te-132 and 134Te h ave been determined in thermal neutron induced fission of U-233, U-235 , Pu-239, Pu-241 and Cm-245 using direct gamma spectrometric and radio chemical techniques. Charge distribution systematics e.g., the width p arameter (sigma(z)), most probable charge (Z(p)) and magnitude of char ge polarization (AZ) have been deduced in all the four mass chains in these fissioning systems as well as in Cf-249(n(th),f) on the basis of the present and literature data. It is observed that the parameters s igma(z) and DELTAZ show the effect of 50p and 82 n spherical shells. S ystematic increase of sigma(z) values with increase in fissility param eter has been observed in all the four mass chains and is the conseque nce of dynamical effects. Variation of DELTAZ for a fixed heavy mass w ith increase of fissibility parameter on the other hand is interpreted from the point of mass asymmetry.