The cold binary fission of even-even [244][245][246][247][248][249][250][251][252][253][254][255][256][257][258] Cf isotopes has been studied by taking the interacting barrier as the sum of Coulomb and proximity potential. The favorable fragment combinations are obtained from the cold valley plot (plot of driving potential vs. mass number of fragments) and by calculating the yield for charge minimized fragments. It is found that highest yield for 244,246,248 Cf isotopes are for the fragments with isotope of Pb (Z=82) as one fragment, whereas for 250 Cf and 252 Cf isotopes the highest yield is for the fragments with isotope of Hg (Z=80) as one fragment. In the case of 254,256,258 Cf isotopes the highest yield is for the fragments with Sn (Z=50) as one fragment. Thus, the fragment combinations with maximum yield reveal the role of doubly magic and near doubly magic nuclei in binary fission. It is found that asymmetric splitting is favoured for Cf isotopes with mass number A < 250 and symmetric splitting is favoured for Cf isotopes with A > 252. In the case of Cf isotope with A=252, there is an equal probability for asymmetric and symmetric splitting. The individual yields obtained for the cold fission of 252 Cf isotope are compared with the experimental data taken from the γ-γ-γ coincidences technique using Gammasphere.

No abstract

No abstract

Radioactivité des particules lourdes Fission spontané Fission froide binaireWithin the framework of the Coulomb and proximity potential model (CPPM), we studied the cold binary fission of even-even 230-250 U isotopes using the two versions of the nuclear proximity potential, Proximity 1977 and Proximity 2000. The most favorable binary fission path is the one that has a high Q value and a minimum driving potential with respect to the mass and charge asymmetries. A nucleus with doubly-closed shell or near doublyclosed shell always appears as the heaviest nucleus in the favored channel of the binary fission of all the mentioned isotopes. For the 230,232,234 U isotopes, the highest yield was predicted for the isotope of Pb (Z = 82) as one fragment, whereas for the 236 U isotope, fragmentation with the isotope of Hg (Z = 80) as one fragment possesses the highest yield. For the 238 U isotope, fragmentation with the isotope of Pt (Z = 78, N = 126) as one fragment possesses the highest yield. In the case of the 240,242,244,246,248,250 U isotopes, the highest yield is for the fragmentation with Sn (Z = 50) as one fragment. It was found that asymmetric splitting is superior for U isotopes with mass number A ≤ 238 and symmetric splitting is superior for U isotopes with A ≥ 240. The computed penetrability and half-lives using the two different proximity potentials for the cold binary fission of 230-250 U isotopes were compared with the available experimental data collected from Holden et al. [Pure Appl. Chem. 72 (2000) 1525]. The two results were found to be in agreement with each other.

Abstract:Within the frame work of Coulomb and proximity potential model (CPPM)