Characterization of the scission point from fission-fragment velocities

Abstract

The isotopic-yield distributions and kinematic properties of fragments produced in transfer-induced fission of 240Pu and fusion-induced fission of 250Cf, with 9 MeV and 45 MeV of excitation energy respectively, were measured in inverse kinematics with the spectrometer VAMOS. The kinematic properties of identified fission fragments allow to derive properties of the scission configuration such as the distance between fragments, the total kinetic energy, the neutron multiplicity, the total excitation energy, and, for the first time, the proton- and neutron-number sharing during the emergence of the fragments. These properties of the scission point are studied as functions of the fragment atomic number. The correlation between these observables, gathered in one single experiment and for two different fissioning systems at different excitation energies, give valuable information for the understanding and modeling of the fission process.Comment: 12 pages, 8 figure

Impact of pear-shaped fission fragments on mass-asymmetric fission in actinides

“…In contrast, a compact system with near spherical fragments at scission is usually associated to larger TKE. The TKE computed from our microscopic simulations, following the method introduced in Ref., 12 are in very good agreement with experimental data 30,31 (see Extended Data Tab. 1 and Fig.…”

Isotopic fission-fragment distributions of U238, Np239, Pu240Ramos1, Caamaño2, Farget3 et al. 2018Phys. Rev. CSelf Cite415150View full textAdd to dashboardCite

“…19. In general, mass distributions present a nonsymmetric shape due to both the neutron evaporations before scission that shift the distribution to lower masses [37] and the neutron evaporation from the fragments after scission that is not constant along the fragment distribution [33,34,46].…”

Dual Position Sensitive MWPC for tracking reaction products at VAMOS++

“…In the compact configuration of the AGATA, the event-by-event measurement of the interaction point on the target is important to ensure the stability of the beam spot size and position throughout the experiment. For experiments employing direct reactions relying on the kinematical energyangular correlations [5,9], the precise determination of the interaction point at the target is essential.…”

“…Heavy-ion fusion reactions in conjunction with large γ-ray detector arrays have been used to understand behaviour of nuclei at the extremes of angular momentum [1]. Isotopically identified fission fragments, from fission induced by heavy-ion fusion or transfer, have been recently used to characterize neutron-rich nuclei at large angular momentum [2,3] and also to study the multidimensional facets of the fission process [4,5]. More peripheral collisions, around the Coulomb barrier, have also played a role in understanding the mechanism of nuclear transfer [6] and to populate nuclei far away from stability [7,8].…”