Evolution of isotopic fission-fragment yields with excitation energy

Delaune, O.; Caamaño, M.; Derkx, X.; Farget, F.; Schmidt, K.‐H.; Tarasov, O.; Audouin, L.; Amthor, A. M.; Bacri, C.O.; Barreau, G.; Bastin, B.; Bazin, D.; Benlliure, J.; Blank, Β.; Cáceres, L.; Casarejos, E.; Fernández–Domínguez, B.; Gaudefroy, L.; Golabek, C.; Grévy, S.; Jurado, B.; Kamalou, O.; Lemasson, A.; Lukyanov, S. M.; Mittig, W.; Morrissey, D. J.; Navin, A.; Pereira, J.; Perrot, L.; Rejmund, M.; Roger, T.; Saint‐Laurent, M. G.; Savajols, H.; Schmitt, C.; Sherrill, B. M.; Stödel, C.; Taïeb, J.; Thomas, J. C.; Villari, A. C. C.

doi:10.1051/epjconf/20123100025

Cited by 4 publications

(1 citation statement)

References 12 publications

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“…The large-acceptance VAMOS spectrometer [28] was used for the identification of the fission fragments, described in detail in Refs. [15,29,30]. In the present work, it was used as a fission-event detector.…”

Section: Experimental Set-upmentioning

confidence: 99%

Transfer reactions in inverse kinematics: An experimental approach for fission investigations

et al. 2014

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Inelastic and multi-nucleon transfer reactions between a 238 U beam, accelerated at 6.14 MeV/u, and a 12 C target were used for the production of neutron-rich, fissioning systems from U to Cm. A Si telescope, devoted to the detection of the target-like nuclei, provided a characterization of the fissioning systems in atomic and mass numbers, as well as in excitation energy. Cross-sections, angular and excitation-energy distributions were measured for the inelastic and transfer channels. Possible excitations of the target-like nuclei were experimentally investigated for the first time, by means of γ-ray measurements. The decays from the first excited states of 12 C, 11 B and 10 Be were observed with probabilities of 0.12 -0.14, while no evidence for the population of higher-lying states was found. Moreover, the fission probabilities of 238 U, 239 Np and 240,241,242 Pu and 244 Cm were determined as a function of the excitation energy.

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Section: Experimental Set-upmentioning

confidence: 99%

Transfer reactions in inverse kinematics: An experimental approach for fission investigations

et al. 2014

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Isotopic fission fragment distributions as a deep probe to fusion-fission dynamics

Farget

Caamaño

Delaune

et al. 2013

J. Phys.: Conf. Ser.

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Abstract. During the fission process, the atomic nucleus deforms and elongates up to the two fragments inception and their final separation at the scission deformation. The evolution of the nucleus energy with deformation defines a potential energy landscape in the multidimensional deformation space. It is determined by the macroscopic properties of the nucleus, and is also strongly influenced by the single-particle structure of the nucleus, which modifies the macroscopic energy minima. The fission fragment distribution is a direct consequence of the deformation path the nucleus has encountered, and therefore is the most genuine experimental observation of the potential energy landscape of the deforming nucleus. Very asymmetric fusionfission reactions at energy close to the Coulomb barrier, produce well-defined conditions of the compound nucleus formation, where processes such as quasi-fission, pre-equilibrium emission and incomplete fusion are negligible. In the same time, the excitation energy is sufficient to reduce significantly structural effects, and mostly the macroscopic part of the potential is responsible for the formation of the fission fragments. We use inverse kinematics combined with a spectrometer to select and identify the fission fragments produced in 238 U+ 12 C at a bombarding energy close to and well-above the Coulomb barrier. For the first time, the isotopic yields are measured over the complete atomic-number distribution, between Z=30 and Z=63. In the experimental set-up, it is also possible to identify transfer-induced reactions, which lead to low-energy fission where the nuclear shell structure shows a strong influence on the fission-fragment distributions. The resulting set of data gives the possibility to observe the fission fragment properties over a wide range of excitation energy, and they reveal the vanishing of the shell effects in the potential energy of the fissioning nucleus, as well as the influence of fission dynamics. IntroductionFragment mass distributions produced in low excitation-energy fission of trans-uranium actinides are known for a long time to present in general a double-humped structure, the fragments being divided in two distinct groups, a heavy-fragment group and a light-fragment one [1]. With increasing mass of the fissioning nucleus, the heavy-fragment group shows a constant average mass, close to the value A=140, whereas the average mass of the light-fragment group increases. This double-humped structure has been understood as a signature for shell-structure influence in the potential energy describing the deforming nucleus from the ground state to the scission point deformation. The constant position of the heavy fragment distribution lead to the comprehension that the shell influence is in fact the single-particle structure inside the nascent fragments, and not in the fissioning nucleus. The most spread model for the description of the fission fragment distribution is based on the macro-microscopic description of the fissioning nucleus potential energy [2, 3...

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Description of isotopic fission-fragment distributions within the Langevin approach

2015

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International audienceDynamical calculations based on the four-dimensional stochastic Langevin approach are extended to thedescription of fragment isotopic distributions in fission at moderate-to-high excitation energy. Benefiting fromprevious theoretical work on charge-asymmetry relaxation times, and existing experimental charge-dispersioncurves from low-energy fission, charge fluctuations are introduced at the scission point in an effective way.Comparison with recent suited measurements shows a good description over the full fragment production. Thedevelopment proposed in this work can easily be implemented in other codes used in the field

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Evolution of isotopic fission-fragment yields with excitation energy

Cited by 4 publications

References 12 publications

Transfer reactions in inverse kinematics: An experimental approach for fission investigations

Transfer reactions in inverse kinematics: An experimental approach for fission investigations

Isotopic fission fragment distributions as a deep probe to fusion-fission dynamics

Description of isotopic fission-fragment distributions within the Langevin approach

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