Speaker
Description
The anatomy of nuclear fission - a complex many-body process that has challenged precise modeling for decades - is explored via a comprehensive inverse-kinematics experiment. A Coulomb-fission measurement of relativistic $^{234,235}$U and $^{237,238}$Np projectiles at the GSI, using the R3B/SOFIA setup [1,2,3,4], was performed to identify on an event-by-event basis, in terms of their mass and atomic numbers, the fissioning nucleus in coincidence with both fission fragments after prompt-neutron emission.
This experiment has provided some of the most precise fission-fragment yields yet for these uranium isotopes and the first isotopic yields for two neptunium isotopes. Moreover, the high accuracy of our data allowed us to study in detail total prompt-neutron multiplicity, from the difference of masses of the fissioning nucleus and fission fragments. Finally by combining the measured isotopic yields with the measured total prompt-neutron multiplicity, a method to infer the number of neutrons of the primary fission fragments prior to the neutron evaporation phase is proposed. The average number of neutron of the primary fission fragments as a function of their atomic number is thus obtained.
Bibliography:
[1] J.-F. Martin et al., accepted for publication in Phys. Rev. C.
[2] E. Pellereau et al., Phys. Rev. C 95, 054603 (2017).
[3] A. Chatillon et al., Phys. Rev. C 99, 054628 (2019).
[4] A. Chatillon et al., Phys. Rev. Lett. 124, 202502 (2020).