An analysis of nuclear fissility for intermediate-energy proton induced reactions

Abstract

In the framework of cascade-evaporation model for nuclear reactions and the liquiddrop model for fission the experimental data on nuclear fissility by protons with energy < 1 GeV was analysed. The authors studied the influence on the value of fissility of the shell effects, pre-equilibrium particle emission from the excited nuclei and the dependence of the height of the fission barriers on the energy of the excited nucleus.

Cross sections of 102 element isotopes formation in the reactions of22Ne+236U and26Mg+232Th

“…Basing on calculation [25] one can conclude that the experimentally observed decrease of the cross sections for the 4n and 5n reactions at the transition from the 160 ions to the ions of 26Mg is described by an Coulomb barrier factor, the location of the maxima of the probability of the deexcitation function and its shape. In the case of the calculations [24] the conclusion could be different. In this case an agreement between the calculations and the experimental data was achieved by the reduction of the diffuseness parameter in the Woods-Saxon potential of the total interaction potential for the reactions induced by 22Ne and 26Ms.…”

“…Thus, one can assume that the lowering of the cross section values at the transition from oxygen to magnesium ions will be smaller for the 6n channel than for the 5n-channel. This difference in the production cross sections behaviour with the increas- [24,25] ing of the projectile mass could be interpreted as the manifestation of an additional entrance channel limitation for the fusion in the reaction with the 22Ne and 26Mg ions [5]. But in our case we deal with the deeply subbarrier reactions.…”

“…The comparison of the experimental data for the maximum cross section values with the predictions of the two model calculations [24,25] is presented in Table 2 and illustrates clearly above mentioned aspect of the problem. The both calculations are based on the statistical model of deexcitation of the produced compound nuclei.…”

“…In the both calculations the model parameters were derived from the best description of a large set of experimental data on the production cross sections for the nuclides with Z_>__98 in the reactions of the "cold" and the "hot" synthesis. In the model of [24] the semiempirical parametrization of the F~/Ff dependencies on the Z, A of the compound nucleus, its excitation energy and transfered angular momentum is used. In the model of [25], based on the ALICE code, the semiempirical parametrization for the "effective" fission barrier values is performed.…”

Analysis of209Bi and238U photofission cross section in the quasi-deuteron region of photonuclear absorption

“…fm is the square of the electron charge, and 1.14fm and 2.16 fm are the equivalent root-meansquare radii of the charge distribution, respectively, for proton and alpha particle as evaluated from data compiled by Brown et al [34]. For the level-density parameter of the residual nucleus after neutron evaporation, a n, it has been adopted the expression proposed by Iljinov et al [16], which incorporates corrections due to excitation energy and shell effects as well. Accordingly, a n = (0.134 A -1.21 • 10-4A 2)…”