Charge distribution studies in the odd- Z fissioning systems

Abstract

Charge distribution studies have been carried out in the odd- Z fissioning systems by determining the isobaric and isotopic yields for heavy mass fission products in the fast neutron induced fission of 237Np, 241Am and 243Am using radiochemical and gamma ray spectrometric technique. From the yields data the width parameter ( σ Z / σ A ), the most probable charge ( Z P ) / mass ( A P ) as well as the elemental yields ( Y Z ) of Sn, Sb, Te, I, Xe, Cs, Ba, La, Ce and Pr were deduced. From the elemental yields local even–odd effects for proton ( D Z ) were obtained in the odd- Z fissioning systems. The charge polarization (Δ Z) as a function of fragment mass ( A ′ ), the slope of charge polarization with mass asymmetry [ δ ( Δ Z ) / δ A ′ ] and average isobaric dispersion parameter ( 〈 σ Z 〉 ) were also obtained for these fissioning systems. The δ ( Δ Z ) / δ A ′ , 〈 σ Z 〉 , D Z and Y Z of various elements in the above three fissioning systems were determined for the first time. These data in the odd- Z fissioning systems (e.g. 238,239Np * and 242,244Am *) from present and earlier work are compared with the literature data for other odd- Z fissioning systems (e.g. 212–226Ac * and 224–232Pa *) and even- Z fissioning systems (e.g. 217–233Th *, 230–239U *, 239–242Pu *, 244Cm(SF), 245,246Cm *, 250Cf * and 252Cf(SF)) to examine the role of nuclear structure effect (e.g. even–odd effect and shell effect). The dynamics of descent from saddle to point of neck formation and from the latter to the scission point are also discussed.