Influence of the neutron numbers of projectile and target on the evaporation residue cross sections in hot fusion reactions

Within the framework of a dinuclear system model, the influence of projectile and target neutron number on capture cross section, fusion probability, and survival probability for the reactions ${}^{34,36}\mathrm{S}+{}^{238}\mathrm{U}$ and ${}^{48}\mathrm{Ca}+{}^{239,240,242,244}\mathrm{Pu}$ are investigated. The calculated excitation functions are in good agreement with the experimental data. To synthesize more unknown neutron-deficient isotopes of already-known superheavy elements, the possibility of using lighter calcium isotopes to induce hot fusion reactions is investigated and the maximal evaporation residual cross sections for ${}^{44,46,48}\mathrm{Ca}$-induced hot fusion reactions to produce unknown neutron-deficient superheavy nuclei with $Z=112–116$ are predicted.

Figure 1

The excitation functions for the reactions (a) ${}^{34}\mathrm{S}+{}^{238}\mathrm{U}$ and (b) ${}^{36}\mathrm{S}+{}^{238}\mathrm{U}$. The calculated results and experimental data [31, 32] are denoted by lines and symbols, respectively. The $3n,4n$, and $5n$ channels are indicated by the solid, dashed, and dash-dotted lines, respectively. The arrows denote the positions of the corresponding Coulomb barriers.

Figure 2

(a) The calculated capture cross sections as functions of incident energy in the center-of-mass frame for the reactions ${}^{34,36}\mathrm{S}+{}^{238}\mathrm{U}$. The inset shows the interaction potentials for corresponding reactions. The (b) calculated capture cross section and (c) calculated fusion probability are functions of excitation energy of the CN. The arrows indicate the positions of the corresponding Coulomb barriers.

Figure 3

The comparison of calculated excitation functions with the experimental data for the reactions ${}^{48}\mathrm{Ca}+{}^{239,240,242,244}\mathrm{Pu}$. The experimental data are obtained from Refs. [3, 5, 33, 34]. The calculated results of $2n,3n,4n$, and $5n$ channels are indicated by the dotted, solid, dashed, and dash-dotted lines, respectively.

Figure 4

Maximal values of available experimental data [3, 5, 33, 34] and calculated ER cross sections of $3n$ and $4n$ channels for the reactions ${}^{48}\mathrm{Ca}+{}^{239,240,242,244}\mathrm{Pu}$.

Figure 5

(a) The calculated capture cross sections and (b) fusion probability as functions of excitation energy of the CN for the reactions ${}^{48}\mathrm{Ca}+{}^{239,240,242,244}\mathrm{Pu}$. The vertical arrows denote the positions of Coulomb barriers.

Figure 6

(a) The calculated survival probabilities as functions of the CN excitation energy. The compound nuclei ${}^{287}\mathrm{Fl}^{*},{}^{288}\mathrm{Fl}^{*},{}^{290}\mathrm{Fl}^{*}$, and ${}^{292}\mathrm{Fl}^{*}$ are denoted by solid, dashed, dotted, and dash-dotted lines, respectively. Thick and thin lines show the $3n$ and $4n$ channels, respectively. (b) $\mathrm{\Delta }{B}^{xn}$ (the definition can be seen in text) for the reactions ${}^{48}\mathrm{Ca}+{}^{239,240,242,244}\mathrm{Pu}$. The lines in (b) are used to guide the eye.

Figure 7

(a) Maximal values of calculated ER cross sections of the $4n$ channel and (b) corresponding optimal excitation energies for hot fusion reactions ${}^{42,43,44,46}\mathrm{Ca}+{}^{244}\mathrm{Pu}$ and ${}^{48}\mathrm{Ca}+{}^{238,239,240,242}\mathrm{Pu}$. (c) The ratio of maximal ER cross sections of the $3n$ and $5n$ channels as a function of the mass number of the CN. The horizontal dotted line denotes that the ratio equals 1. The dashed lines are used to guide the eye.