Possibility to produce element 120 in the ${}^{54}$Cr+${}^{248}$Cm hot fusion reaction

Synthesis of element 120 in the ${}^{249}$Cf(${}^{50}$Ti,$xn$)${}^{299-x}$120 and ${}^{248}$Cm(${}^{54}$Cr,$xn$)${}^{302-x}$120 fusion evaporation reactions has been evaluated by means of a modified fusion by diffusion model. It is found that the fusion probability of the system ${}^{54}$Cr+${}^{248}$Cm is two times smaller than that of ${}^{50}$Ti+${}^{249}$Cf. On the other hand, the survival probability of the former is obviously greater than that of the latter. As a result, the loss in the fusion probability of the ${}^{54}$Cr+${}^{248}$Cm reaction is compensated by its gain in survival probability. The calculated maximum evaporation residue cross sections in the ${}^{249}$Cf(${}^{50}$Ti,3$n$)${}^{296}$120 and ${}^{248}$Cm(${}^{54}$Cr,4$n$)${}^{298}$120 reactions are quite close: 0.034 and 0.024 pb, respectively. Besides, as compared to the system ${}^{50}$Ti+${}^{249}$Cf, the ${}^{54}$Cr+${}^{248}$Cm combination has two advantages. First, ${}^{248}$Cm is much easier accumulate a sufficient amount for the target material than ${}^{249}$Cf. Second, the isotope ${}^{298}$120 has 178 neutrons, two neutrons more than the isotope ${}^{296}$120. Therefore, the ${}^{54}$Cr+${}^{248}$Cm combination should be one of most favorable candidates to produce superheavy element 120.

Figure 1

Probability distributions of $s_{inj}$ calculated with the coupled Langevin equations for the systems ${}^{50}$Ti+${}^{249}$Cf and ${}^{54}$Cr+${}^{248}$Cm at the CN excitation energy $E^{*}=40$ MeV.

Figure 2

Fusion probability as a function of angular momentum for the systems ${}^{50}$Ti+${}^{249}$Cf and ${}^{54}$Cr+${}^{248}$Cm at the CN excitation energy $E^{*}=40$ MeV.

Figure 3

A comparison of the survival probabilities $P_{xn}(E^{*},l=0)$ of the 3$n$ and 4$n$ evaporation channels between the systems ${}^{50}$Ti+${}^{249}$Cf (dashed lines) and ${}^{54}$Cr+${}^{248}$Cm (solid lines).

Figure 4

The neutron binding energy (open circles) and the absolute value of shell correction (solid circles) as a function of nucleus mass number for the SHE 120. Data are taken from Ref. [6].

Figure 5

Predicted evaporation residue cross sections for the $3n$- and $4n$-evaporation channels in the ${}^{50}$Ti+${}^{249}$Cf (dashed lines) and ${}^{54}$Cr+${}^{248}$Cm (solid lines) reactions.

Figure 6

Comparison between the theoretical predictions and experimental results for the ${}^{136}$Xe+${}^{136}$Xe (a) and ${}^{48}$Ca+${}^{238}$U (b) reactions. The solid lines are our model predictions. The dash-dotted lines are the predictions of Zagrebaev et al. [8, 37]. The hollow bar in panel (a) shows the upper limit of the experimental ER cross sections in the ${}^{136}$Xe+${}^{136}$Xe reaction [38]. The experimental data of the ${}^{48}$Ca+${}^{238}$U reaction are taken from Ref. [2].

Figure 7

Evaporation residue cross sections in the ${}^{50}$Ti+${}^{249}$Cf (a) and ${}^{54}$Cr+${}^{248}$Cm (b) fusion reactions. The solid lines show our predictions, whereas the dashed and dash-dotted lines are the predictions of Refs. [8, 39], respectively.

Figure 8

Recalculated ER cross sections for the ${}^{54}$Cr+${}^{248}$Cm system based on the even-even nucleus fission barrier of Warsaw (solid lines). The dashed lines are the predictions of Siwek-Wilczyńska et al. [39].