Effects of fissioning nuclei distributions on fragment mass distributions for high energy fission

Abstract

Abstract.We study the effects of fissioning nuclei mass-and energy-distributions on the formation of fragments for fission induced by high energy probes. A Monte Carlo code called CRISP was used for obtaining mass distributions and spectra of the fissioning nuclei for reactions induced by 660 MeV protons on 241 Am and on 239 Np, by 500 MeV protons on 208 Pb, and by Bremsstrahlung photons with end-point energies at 50 MeV and 3500 MeV on 238 U. The results show that even at high excitation energies, asymmetric fission may still contribute significantly to the fission cross section of actinide nuclei, while it is the dominante mode in the case of lead. However, more precise data for high energy fission on actinide are necessary in order to allow definite conclusions.

Nuclear photoproduction of vector mesons within a Monte Carlo approach

“…The Pauli exclusion principle is taken into account in CRISP dynamics by rejecting collisions that lead to the final state violating the Pauli principle. All these features enabled CRISP code to successfully simulate reactions induced by protons [40,44], photons [39,41,45,46], electrons [47,48], and other processes such as kaon [49] production and hypernuclei decay [50][51][52]. The effectiveness of such an approach can be verified in the study of evaporation/fission competition [53][54][55], which explained for the first time the saturation below the unit of fissility for heavy nuclei observed in experiments.…”

“…Photoproduction of ρ, ω, and φ mesons was simulated with CRISP code at 9 GeV on nuclei 12 C, 27 Al, 40 Ca, 56 Fe, 63 Cu, 107 Ag, 138 Ba, 153 Eu, 166 Er, 180 W, 197 Au, 208 Pb, and 232 Th. We observe a good agreement between calculations and experimental data; both show a clear deviation from the linear behavior.…”

“…The photoproduction section for J / was calculated on nuclei 40 Ca, 63 with σ 0 and α used as free parameters. The α values obtained for each energy are plotted in Fig.…”

“…A discussion about the advantage of these improved codes with respect to the older codes can be find in Ref. [39][40][41].…”

Superasymmetric fission of heavy nuclei induced by intermediate-energy protons

“…It is important to emphasize that the CRISP code has been used to simulate nuclear reactions of several kinds, such as those induced by protons [33][34][35], photons [19,27,[36][37][38], electrons [39,40], or hypernuclei [21,41,42], with energies from 50 MeV up to 3.5 GeV, and on nuclei with masses going from A = 12 up to A = 240 and with several observables: spallation products, strange particles, fission products, hyperon-decay particles, fragment mass, and atomic number distributions. The code has been applied in the study for development of nuclear reactors [43][44][45].…”