MASS-ENERGY CHARACTERISTICS OF THE REACTIONS ~58Fe+~208Pb->~266HS AND ~26Mg+~248Cm ->~274Hs AT COULOMB BARRIER

摘要

The mass-energy distributions of the fission fragments, fusion-fission (aFF) and capture(a,,) cross-sections in the reactions 58Pb+208Pb and 26Mg+248Cm were measured at theU400 accelerator of Flerov Laboratory of Nuclear Reactions (JINR, Russia) with use ofdouble-arm time-of-flight spectrometer .CORSET. The influence of reaction entrancechannel on the competition between fusion-fission and quasi-fission processes wasstudied. Strong manifestation of the shell effects in mass distributions of fusion-fissionand quasifission fragments was observed. The bimodal fission phenomena were found forboth 266Hs and 274Hs nuclei at low excitation energies. For several beam energies of 26Mgand 58Fe studied in this work, the average neutron multiplicities and y–raymultiplicities in coincidence with fission fragments were also measured. Localminima are observed in as a function of mass suggesting the great influence ofnuclear structure of fission fragments on . The different dependence of and as a function of fission fragment mass, total kinetic energy and excitation energyfor fusion-fission and quasifission processes were observed.