In this work we report the proton-and deuteron-induced fission of 208 Pb at 500A MeV in inverse k... more In this work we report the proton-and deuteron-induced fission of 208 Pb at 500A MeV in inverse kinematics. We obtained two observables that allow us to investigate dynamical effects in the fission process: partial fission cross sections and the width of the fission fragment charge distribution as a function of the atomic number of the fissioning system. Results are compared to nuclear reaction model calculations in order to describe the evolution of the system from ground to saddle.
ABSTRACT We have investigated the total fission cross section of 181Ta+ 1H at 1, 0.8, 0.5 and 0.3... more ABSTRACT We have investigated the total fission cross section of 181Ta+ 1H at 1, 0.8, 0.5 and 0.3 GeV with an specific setup at the FRS (FRagment Separator - GSI). The high-accuracy results obtained in this experiment are compared with calculations performed with an intra-nuclear cascade model (INCL v4.1) coupled to a de-excitation code (ABLAv3p). The calculations reproduce the two different models that describe the fission process at high excitation energies: statistical model of Bohr and Wheeler and the dynamical description of the fission process. Data comparison with previous experiments is also included to point out the existing discrepancies with this new results.
Total fission cross section of Ta+ H at 1, 0.8, 0.5 and 0.3 GeV studied in inverse kinematics
Investigating the fission process at high excitation energies through proton induced reactions on (181)Ta
ABSTRACT In this work we have investigated total fission cross section of 181Ta+1H at FRS (FRagme... more ABSTRACT In this work we have investigated total fission cross section of 181Ta+1H at FRS (FRagment Separator -GSI) at 1, 0.8, 0.5 and 0.3 GeV with an specific setup, providing high accuracy measurements of the cross section values. We compare the results obtained in this experiment, with several calculations performed with the intra-nuclear cascade model (INCL v4.1) coupled to de-excitation code (ABLAv3p), according to two different models describing fission process at high-excitation energies: statistical model of Bohr and Wheeler and the dynamical description of the fission process. The comparison with data of previous experiments is also discussed in order to address the existing discrepancies with this new results.
Total fission cross sections of 181 Ta induced by protons at different relativistic energies have... more Total fission cross sections of 181 Ta induced by protons at different relativistic energies have been measured at GSI Darmstadt using the inverse kinematic technique. These data contribute to solve inconsistencies in previously reported measurements, but also help to benchmark state-of-the-art reaction codes. The energy range covered with these measurements allowed us to investigate the onset and temperature dependence of dissipative and transient effects at small deformation.
On the basis of systematic measurements of fragmentation reactions, which provide a detailed over... more On the basis of systematic measurements of fragmentation reactions, which provide a detailed overview on the velocity distributions of residual nuclei, an improved description of the kinematical properties of the fragmentation residues is established. This work is dedicated to the fluctuations of their momentum distributions. In contrast to previous investigations, limited to close-to-projectile fragments, we extended our study to the entire production range, down to the lightest observed fragments. In this context, beside the contribution of abrasion and evaporation processes, we considered the effect of the thermal break-up on the width of the momentum distributions. Using approximated theoretical descriptions of the different reaction stages, a new analytical formula for the variance of the momentum distribution is derived, which is well adapted to technical applications.
ABSTRACT Spallation reactions on fissile nuclei represent an appropriate tool to investigate diss... more ABSTRACT Spallation reactions on fissile nuclei represent an appropriate tool to investigate dissipative effects in nuclear fission. In this work, we have studied transient and dissipative effects in proton- and deuteron-induced fission on $^{208}\mathrm{Pb}$ at $500A$ MeV. A dedicated experimental setup optimized for inverse kinematics measurements made it possible to identify in atomic number both fission fragments with high resolution, and reconstruct the charge of the fissioning system. We could then determine the width of the fission fragments charge distribution as well as partial fission cross sections, both as a function of the charge of the fissioning system. These two complementary observables permitted us to investigate the dynamics of the process at small deformation, i.e., from the ground state to the saddle point. The description of these observables with advanced model calculations reveals the influence of the nuclear dissipation in the fission process at high excitation energy and in particular its manifestation through transient time effects.
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Papers by A. Bacquias