Charge distribution of heavy mass fission products in the thermal neutron induced fission of 233U, 235U and 239Pu

Isobaric charge distribution has been carried out in the thermal neutron induced fission of U-233, U-235 and Pu-239 by measuring the fractional cumulative yields (FCY) of various heavy mass fission products within the range of 127-149. An off-line gamma-ray spectrometric technique was used for the measurement of fission product activities. The width of the isobaric charge distribution (sigma(Z)), most probable charge (Z(P)) and thus the experimental charge polarization (Delta Zeta(EXPT)) as a function of fragment mass were obtained. It was found that the sigma(Z) values around the mass number 127-129 and 132-136 are lower due to the presence of spherical 50p and 82n shells. The Delta Zeta(EXPT) values show an oscillating nature in the interval of five mass units due to even-odd effect. The Delta Zeta(EXPT) values also show a decreasing trend with the approach of symmetric split besides an oscillating nature. The most probable charge (Z(MPE)) and thus the Delta Zeta(MPE) values based on the minimum potential energy surface were theoretically calculated, which show a systematic decreasing trend with the approach of symmetric split due to the liquid drop behaviour of the fissioning nucleus.