Dynamical evolution of angular momentum in damped nuclear reactions

Døssing, T.; Randrup, J.

doi:10.1016/0375-9474(85)90179-4

Cited by 47 publications

(8 citation statements)

References 28 publications

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“…Many investigations of the relaxation time in fusion-fission and quasifission reactions [20,22,52,61,62,[97][98][99][100][101][102] predict a value of τ K ranging from ∼10 −21 s to ∼10 −20 s depending on the spin, transition-state deformation, and type of the investigated reaction. The γ K and I influence τ K in a different way.…”

Section: The Angular Distribution Of Fission Fragmentsmentioning

confidence: 99%

Four-dimensional Langevin dynamics of heavy-ion-induced fission

et al. 2012

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A four-dimensional dynamical model based on Langevin equations was developed and applied to calculate a wide set of experimental observables for the reactions 16 O + 208 Pb → 224 Th and 16 O + 232 Th → 248 Cf over a wide range of excitation energy. The fusion-fission and evaporation residue cross sections, fission fragment mass-energy distribution parameters, prescission neutron multiplicities, and anisotropy of angular distribution of fission fragments could be reasonably reproduced using a modified one-body mechanism for nuclear friction with a reduction coefficient of the contribution from a wall formula k s 0.25 and a dissipation coefficient for the orientation degree of freedom (K coordinate) γ K 0.077 (MeV zs) −1/2 . Inclusion of the K coordinate into calculation of potential energy changes the stiffness of the nucleus with respect to mass asymmetry coordinate for the values of K = 0 and results in a shift of the Businaro-Gallone point towards larger Z 2 /A values. The experimental data on the fission fragment mass-energy distribution parameters together with mean prescission neutron multiplicity for heavy fissioning nuclei are reproduced through the four-dimensional Langevin calculations more accurately than through three-dimensional calculations.

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Section: The Angular Distribution Of Fission Fragmentsmentioning

confidence: 99%

Four-dimensional Langevin dynamics of heavy-ion-induced fission

et al. 2012

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“…Therefore we have used the Nucleon Exchange Transport model, [25] which has no adjustable parameters and has successfully reproduced such diverse phenomena as energy dissipation in damped reactions, [26] entrance-channel mass asymmetry dependence of the probability for fusion, [27] and the time delay observed in collisions of very heavy nuclei as probed by electron-positron production. [28] With regard to dissipative reactions, the model successfully accounts for the energy loss dependencies of the variances of the Nand Z distributions, [29] the magnitude and alignment of the transferred angular momentum, [30] and the partition of the excitation energy between projectile-like and target-like fragments. [31] Second, we wish to determine to what extent one ca~ understand the qualitative features of such pre-equilibrium emission, especially the apparent source velocity and the spectral shape, in terms of energy dissipation prior to the particular nucleon transfer that led to pre-equilibrium emission.…”

Section: Introductionmentioning

confidence: 99%

Pre-equilibrium neutron emission in the nucleon exchange transport model

Randrup

Vandenbosch

1987

Nuclear Physics A

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LBL-23359We extend the Nucleon Exchange Transport model to include the emission of pre-equilibrium neutrons as a result of nucleon transfer to unbound states. The treatment takes account of the heating of the two nuclei caused by the energy dissipation and the cooling due to the pre-equilibrium emission. Furthermore, the transferred nucleons may induce cascading in the receptor nucleus by means of direct two-body scattering with the resident nucleons, based on a reduced, Pauli-blocked, energy-dependent free N N cross section. Qualitative agreement with experimental data is achieved, but the absolute multiplicities are systematically underestimated by about a factor of two. The dependence of multiplicity on bombarding energy is reproduced. The energy spectra and their variation with angle are generally reproduced, although the yield of the highest energy particles is sometimes underestimated.

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“…[116,117] and (2-4) × 10 −21 s in [51,118] from fits of the calculated values to experimental data on the anisotropy of the angular distribution for heavy fissioning compound systems. Theoretical estimates of the relaxation time for the K mode and for other rotational modes in deep-inelastictransfer reactions were obtained in [157,210], where use of the ideas of nucleon-transport theory in nuclear collisions with allowance for quantum effects [211] was made. In refs.…”

Section: Energy Dependence Of the Anisotropy Of The Angular Distributionmentioning

confidence: 99%

“…In refs. [157,210], the relaxation time τ K for the tilting mode was estimated in the limits at (2-20)×10 −21 s, the specific value being dependent on the total angular momentum of the system.…”

Section: Energy Dependence Of the Anisotropy Of The Angular Distributionmentioning

confidence: 99%

“…However, in this case, the problem of calculating the conservative force and the transport parameters (inertial and friction) for the tilting mode arises. The works of Døssing [157,210], Randrup [158] and Lestone [115] partially solved those problems, particularly by the use of the overdamped treatment of the K-coordinate dynamic. This assumption took away the open question with inertial tensor for the tilting mode.…”

Section: Angular Distribution Within 4d Langevin Dynamicsmentioning

confidence: 99%

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Fission fragment distributions within dynamical approach

et al. 2017

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The review covers recent developments and achievements in the dynamical description of fission process at high excitation energy. It is shown that the dynamical approach based on multidimensional Langevin equations combined with the statistical description of nuclear decay by particles evaporation is capable of fairly well describing the formation of fission fragment mass-energy, charge, and angular distributions of fission fragments in coincidence with the pre-and post-scission particle emission. The final yields of fission and evaporation residues channels products could be obtained. The detailed description of fission dynamics allows studying different stages of fission process, indicating the most important ingredients governing fission process and studying in detail such fundamental nuclear properties as nuclear viscosity and fission timescale. The tasks and perspectives of multidimensional dynamical approach are also discussed.

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Dynamical evolution of angular momentum in damped nuclear reactions

Cited by 47 publications

References 28 publications

Four-dimensional Langevin dynamics of heavy-ion-induced fission

Four-dimensional Langevin dynamics of heavy-ion-induced fission

Pre-equilibrium neutron emission in the nucleon exchange transport model

Fission fragment distributions within dynamical approach

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