Dynamics of the fusion process

Study of fusion reactions forming Cf nuclei

“…For 12 C+ 235 U, M R distributions are expected to have a Gaussian shape, as predicted by the Rotating Liquid Drop Model (RLMD) of CN-fission [24]. However, measured M R distributions of 12 C+ 235 U exhibit flat-top shapes at all measured excitation energies (see Fig. 1).…”

“…This is a clear indication that the fission fragments originate from re-separation of the twocenter system during rotation. Such behavior of the fission fragments is a well-understood sign of the quasifission process [10][11][12][13]18] and represents the dynamical evolution of the two captured nuclei that do not form a CN. A characteristic reaction timescale of ≤10 -20 s has been found [18] to describe experimental MAD data in systems where quasi-fission probabilities are significant, which agrees with results obtained using the neutronclock methods [19].…”

“…Corresponding M R distributions of the fission fragments originating from fusion-fission and quasifission in 12 12 C+ 235 U, in which fusion-fission is solely assigned as the origin of these fission events. Therefore, at first sight, these fission events may also be thought to originate from fusion-fission forming the 242 Cf* CN.…”

“…[7,12,13]. However, such assigned can be done only in the case of the quasi-fission which occurs from a non-equilibrated system.…”

Long lifetime components in the decay of excited super-heavy nuclei

“…Therefore, experimental fusion cross-sections can only be reached through fission fragment detection. However, the distinction between fusion followed by fission (fusion-fission) and faster non-equilibrium processes (often called quasi-fission) is very tricky because the fission fragments and fission-like fragments from quasi-fission can be quite similar in mass, atomic number and energy [1][2][3].…”