Abstract
Fission cross sections have been measured for the systems of ${}^{11}\mathrm{B},$ ${}^{16}\mathrm{O},$ ${}^{19}{\mathrm{F}+}^{232}\mathrm{Th}$ in the sub-barrier to extreme-sub-barrier energy (ESBE) region. Two position sensitive avalanche detectors were employed to measure the fission events due to fusion-fission (FF) and transfer fission (TF) processes using the fission fragment folding angle technique. The cross sections for fusion-fission reactions could be well accounted by the coupled channel calculations over a large energy range except in the ESBE region. The transfer induced fission cross sections are observed to be large at extreme sub-barrier energies. The ratio of transfer fission cross section to that of total fission is observed to increase rapidly as the energy is decreased in the sub-barrier region for all the systems. Also in the ESBE region a number of low momentum transfer fission (LMTF) events having folding angle close to $180\ifmmode^\circ\else\textdegree\fi{}$ are observed with a rather weak dependence on the bombarding energy. These events were investigated by several control experiments. Considering the uncertainties involved in the control experiments, it appears difficult to rule out if they originate completely from background neutron induced reactions or from any new process such as Coulomb fission as conjectured in some earlier studies. The results on different components of the fission cross sections have been discussed.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.