Excitation-energy sharing in20Ne induced reactions

1986 ◽  
Vol 324 (1) ◽  
pp. 121-122
Author(s):  
C. P. M. Engelen ◽  
E. A. Bakkum ◽  
R. J. Meijer ◽  
R. Kamermans
2021 ◽  
Vol 256 ◽  
pp. 00013
Author(s):  
Jørgen Randrup ◽  
Martin Albertsson ◽  
Gillis Carlsson ◽  
Thomas Døssing ◽  
Peter Möller ◽  
...  

The transformation of a moderately excited heavy nucleus into two excited fission fragments is modeled as a strongly damped evolution of the nuclear shape. The resulting Brownian motion in the multi-dimensional deformation space is guided by the shape-dependent level density which has been calculated microscopically for each of nearly ten million shapes (given in the three-quadratic-surfaces parametrization) by using a previously developed combinatorial method that employs the same single-particle levels as those used for the calculation of the pairing and shell contributions to the five-dimensional macroscopic-microscopic potential-energy surface. The stochastic shape evolution is followed until a small critical neck radius is reached, at which point the mass, charge, and shape of the two proto-fragments are extracted. The available excitation energy is divided statistically on the basis of the microscopic level densities associated with the two distorted fragments. Specific fragment structure features may cause the distribution of the energy disvision to deviate significantly from expectations based on a Fermi-gas level density. After their formation at scission, the initially distorted fragments are being accelerated by their mutual Coulomb repulsion as their shapes relax to their equilibrium forms. The associated distortion energy is converted to additional excitation energy in the fully accelerated fragments. These subsequently undergo sequential neutron evaporation which is calculated using again the appropriate microscopic level densities. The resulting dependence of the mean neutron multiplicity on the fragment mass, as well as the dependence of on the initial excitation energy of the fissioning compound nucleus, exhibit features that are similar to the experimentally observed behavior, suggesting that the microscopic energy sharing mechanism plays an important role in low-energy fission.


1990 ◽  
Vol 336 (2) ◽  
pp. 217-222 ◽  
Author(s):  
G. Beier ◽  
J. Friese ◽  
W. Henning ◽  
P. Kienle ◽  
H. J. K�rner ◽  
...  

1999 ◽  
Vol 651 (3) ◽  
pp. 225-236 ◽  
Author(s):  
O. Dorvaux ◽  
L. Stuttgé ◽  
F. Hanappe ◽  
G. Rudolf ◽  
G. Bizard ◽  
...  

2021 ◽  
Vol 256 ◽  
pp. 00007
Author(s):  
F.A. Ivanyuk ◽  
S. Chiba

We apply the four-dimensional Langevin approach to the description of fission of 235U by neutrons and calculate the dependence of the excitation energy of fission fragments on their mass number. For this we run the Langevin equations until the compound nucleus splits into two separated fragments. This is possible since the we used in this work two-center shell model shape parametrization that describes well both compact and separated shapes. The excitation energies of each fragment are calculated assuming that the temperatures of both fragments are the same. The deformation energy of the fragment immediately after scission is added to its excitation energy. The saw-tooth structure of the dependence neutron multiplicity on the fragment’s mass number in reaction 235U + n at En = 5 Mev is qualitatively reproduced.


2021 ◽  
Vol 256 ◽  
pp. 00016
Author(s):  
Ionel Stetcu ◽  
Aurel Bulgac ◽  
Shi Jin ◽  
Kenneth J. Roche ◽  
Nicolas Schunck

Recent developments, both in theoretical modeling and computational power, have allowed us to make progress on a goal not fully achieved yet in nuclear theory: a microscopic theory of nuclear fission. Even if the complete microscopic description remains a computationally demanding task, the information that can be provided by current calculations can be extremely useful to guide and constrain more phenomenological approaches, which are simpler to implement. First, a microscopic model that describes the real-time dynamics of the fissioning system can justify or rule out some of the approximations. Second, the microscopic approach can be used to obtain trends, e.g., with increasing excitation energy of the fissioning system, or even to compute observables that cannot be otherwise calculated in phenomenological approaches or that can be hindered by the limitations of the method. We briefly present in this contribution the time-dependent superfluid local density approximation (TDSLDA) approach to nuclear fission, approach that has become a very successful theoretical model in many areas of many-body research. The TDSLDA incorporates the effects of the continuum, the dynamics of the pairing field, and the numerical solution is implemented with controlled approximations and negligible numerical errors. The main part of the current contribution will be dedicated to discussing the method, and recent results concerning the fission dynamics. In addition, we present results on the excitation energy sharing between the fragments, which are in agreement with a qualitative conclusions extracted from a limited number of experimental measurements of properties of prompt neutrons.


1987 ◽  
Vol 467 (2) ◽  
pp. 349-364 ◽  
Author(s):  
H. Sohlbach ◽  
H. Freiesleben ◽  
W.F.W. Schneider ◽  
D. Schüll ◽  
P. Braun-Munzinger ◽  
...  

2008 ◽  
Vol 78 (6) ◽  
Author(s):  
S. Piantelli ◽  
A. Mangiarotti ◽  
P. R. Maurenzig ◽  
A. Olmi ◽  
L. Bardelli ◽  
...  

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