Using experimental data to test an $n$-body dynamical model coupled with an energy-based clusterization algorithm at low incident energies

Employing the quantum molecular dynamics (QMD) approach for nucleus-nucleus collisions, we test the predictive power of the energy-based clusterization algorithm, i.e., the simulating annealing clusterization algorithm (SACA), to describe the experimental data of charge distribution and various event-by-event correlations among fragments. The calculations are constrained into the Fermi-energy domain and/or mildly excited nuclear matter. Our detailed study spans over different system masses, and system-mass asymmetries of colliding partners show the importance of the energy-based clusterization algorithm for understanding multifragmentation. The present calculations are also compared with the other available calculations, which use one-body models, statistical models, and/or hybrid models.

Figure 1

The normalized charge distribution obtained in the central reactions of ${}^{129}\mathrm{Xe}+{}^{119}\mathrm{Sn}$ and ${}^{155}\mathrm{Gd}+{}^{238}\mathrm{U}$ at an incident energy of 32 and 36 MeV/nucleon, respectively. The stars represent experiment data [6] and squares represent the calculations of QMD coupled with SACA algorithm. The results of previous attempts [6, 31] are also displayed for comparison.

Figure 2

The charge distribution obtained in the central reactions of ${}^{129}\mathrm{Xe}+{}^{119}\mathrm{Sn}$ and ${}^{155}\mathrm{Gd}+{}^{238}\mathrm{U}$ at an incident energy of 32 and 36 MeV/nucleon, respectively. The solid histograms represent experiment data [33] and the squares represent the calculations of QMD coupled with the SACA algorithm. The results of previous attempts [33] are also displayed for comparison.

Figure 3

The probability distribution of the first three largest charges emitted in central reactions of ${}^{129}\mathrm{Xe}+{}^{119}\mathrm{Sn}$ (top panels) and ${}^{155}\mathrm{Gd}+{}^{238}\mathrm{U}$ (bottom panels) at incident energies of 32 and 36 MeV/nucleon, respectively. Crossed triangles and crossed circles represent, respectively, the results of calculations 1 and 2 within the framework of the MMM model [33]. Other symbols have the same meaning as in Fig. 2.

Figure 4

Probability distribution of multiplicities of IMFs emitted in central reactions of ${}^{129}\mathrm{Xe}+{}^{119}\mathrm{Sn}$ (top-left panels) and ${}^{155}\mathrm{Gd}+{}^{238}\mathrm{U}$ (bottom-left panel) at incident energies of 32 and 36 MeV/nucleon, respectively [13, 33]. In the right panel is the probability distribution the charge of the IMFs emitted as bound fragments for the reactions of ${}^{155}\mathrm{Gd}+{}^{238}\mathrm{U}$ at an incident energy of 36 MeV/nucleon. Symbols have the same meaning as in Figs. 1 and 2.

Figure 5

The charge distribution obtained in the central reactions of ${}^{40}\mathrm{Ca}+{}^{40}\mathrm{Ca}$ at an incident energy of 35 MeV/nucleon. The stars represent the experiment data [35], and solid, dotted, and dashed histograms represent the calculations of Sa and Gross [36], Richert and Wagner [37], and gemini [24] models, respectively. The calculation obtained by using QMD coupled with SACA are represented by open squares.

Figure 6

The charge distribution obtained in the central reaction of ${}^{197}\mathrm{Au}+{}^{197}\mathrm{Au}$ at an incident energy of 35 MeV/nucleon. The stars represent the experimental data points extracted from Ref. [7]. The calculations obtained by using $\text{QMD}+\text{SACA}$ are represented by open squares. The results of the statistical multifragmentation model (smm) are also displayed for comparison [7].

Figure 7

Probability distribution of first six largest charges emitted in central reactions of ${}^{197}\mathrm{Au}+{}^{197}\mathrm{Au}$ at an incident energy of 35 MeV/nucleon [7]. Symbols have the same meaning as in Fig. 6.