Nucleon removal from unstable nuclei investigated via intranuclear cascade

An intranuclear cascade model for one-nucleon removal cross sections at intermediate energies beyond the sudden and inert-core assumptions is presented. Indirect processes are taken into account in the reaction mechanism via a Monte Carlo–based approach. The formalism is applied to a set of weakly bound nuclei for which data are available. Results are in correct agreement with experiment including the case of deeply bound nucleon removal. A comparison to eikonal predictions is performed.

Figure 1

Schematic description of events that contribute to the one-nucleon removal cross section (from the projectile) and events that, due to processes beyond the Glauber approximation, do not contribute to the one-nucleon removal cross section: (a) knockout, (b) multiple scattering, (c) core excitation followed by evaporation, (d), (e) reinteractions in the medium that lead to a reduction of the one-nucleon removal cross section. Nucleons from the projectile $P$ (target $T$) are in red (blue).

Figure 2

Reaction cross sections for ${}^{14}\mathrm{O}$, ${}^{24}\mathrm{Si}$, ${}^{28}\mathrm{S}$ and ${}^{32}\mathrm{Ar}$ on a ${}^9\mathrm{Be}$ target and for ${}^{24}\mathrm{O}$ on ${}^{12}\mathrm{C}$. The energies considered are those for which one-nucleon removal cross sections have been measured (see text). Predictions from the present work (blue bars) are compared to eikonal predictions (red bars). The energy dependance is illustrated by calculations at 300 MeV/nucleon (triangles).

Figure 3

One-neutron and one-proton removal cross sections for the very asymmetric nuclei ${}^{14}\mathrm{O}$, ${}^{24}\mathrm{Si}$, ${}^{24}\mathrm{O}$, ${}^{28}\mathrm{S}$, and ${}^{32}\mathrm{Ar}$. Experimental data (pink dots) are compared to the present work (blue bars) and eikonal predictions (red bars). The energy dependence of the two formalisms is illustrated by calculations for an incident energy of 300 MeV/nucleon (triangles).

Figure 4

Excitation function restricted to cascade events where ${}^{31}\mathrm{Ar}$ is formed from ${}^{32}\mathrm{Ar}$ $+$ ${}^9\mathrm{Be}$ at 65 MeV/nucleon as a function of the number of $\mathit{NN}$ collisions. Excitation-energy bins are 2 MeV. (inset) Contribution of the different impact parameters to the one-neutron removal ${}^{32}\mathrm{Ar}$(${}^9\mathrm{Be}$,X) ${}^{31}\mathrm{Ar}$. The INC (blue) and eikonal approaches (blue strips) are compared. The population of ${}^{31}\mathrm{Ar}$ from the cascade (light purple) and evaporation (deep purple) are shown.