Study of pre-scission particle emissions and fission probability of the ¹⁷⁸ W produced in fusion reactions

Abstract

A dynamical model based on one-dimensional Langevin equations was used to calculate the average pre-fission multiplicities of neutrons, light charged particles, and the fission probability for compound nucleus 178 W produced in fusion reactions. The pre-scission multiplicities of particles and fission probability are calculated and compared with the experimental data over a wide range of excitation energy. A modified wall and window dissipation with a reduction coefficient, ks, has been used in the Langevin equations for reproducing experimental data. It was shown that the results of the calculations are in good agreement with the experimental data by using values of ks in the range 0.24 ks 0.47.

Spallation reaction versus heavy-ion fusion: Fission excitation functions as a fundamental probe of presaddle nuclear dissipation

“…It has been found in numerous experiments [1][2][3][4][5][6][7][8][9] that when excitation energy deposited into the compound system is increased, the measured prescission particle multiplicity exceeds that estimated by standard statistical models (SMs). This discrepancy has been demonstrated [10][11][12][13][14][15][16][17][18][19][20][21] to arise from dissipation effects that are not accounted for in theoretical calculations. Nuclear dissipation retards the fission process that affects the competition of fission with evaporation, two principle decay modes of highly excited nuclei.…”

“…Towards that goal, we compare the sensitivity of fission cross sections to β for different E * and c in the framework of Langevin models. The stochastic approach [10,[12][13][14][16][17][18]21,38,39] has been utilized to successfully reproduce a great number of experimental data on fission excitation functions and prescission particle multiplicities for a lot of fissioning systems over a wide range of excitation energy, angular momentum, and fissility.…”

Langevin analysis of fission excitation functions induced by protons

“…Previous works [9,11,[20][21][22][23] concerning β employed fission excitation functions provided in heavy-ion reactions, where the formed CNs have a high spin (up to ∼75 ). The high leads to a distortion of the produced CNs at their ground state.…”

“…The high leads to a distortion of the produced CNs at their ground state. The distortion could affect the transient time and this is not accounted for in earlier and current Langevin calculations [8,9,11,17,[21][22][23][24], where a Langevin trajectory starts to simulate fission motion under the assumption that a spherical CN is produced. This neglect causes ambiguity in constraining β when confronting theory with experiment.…”

Study of different features of fission dynamics of 224 Th produced in fusion reactions within a stochastic approach

“…The dynamics of fission can be simulated in terms of the multidimensional Langevin equations or multidimensional Fokker-Planck equation (see, for example Refs. [1][2][3][4][5][6][7][8][9][10][11][12][13][14]). The multidimensional Langevin equations and multidimensional Fokker-Planck equation have been extensively and rather successfully used to solve many problems of collective nuclear dynamics in such reactions as fusion fission, induced fission, heavy ion collisions, and quasifission (see [10][11][12][13] and references therein).…”