Production of neutron-rich nuclei with $Z=60–73$ in reactions induced by Xe isotopes

The multinucleon transfer reactions ${}^{124,136,144}\mathrm{Xe}+{}^{238}\mathrm{U}, {}^{136,144}\mathrm{Xe}+{}^{160}\mathrm{Gd}, {}^{136,144}\mathrm{Xe}+{}^{170}\mathrm{Er}$, and ${}^{136,144}\mathrm{Xe}+{}^{186}\mathrm{W}$ are investigated within the framework of the dinuclear system model. The charge equilibration effects on the production cross sections of exotic nuclei are studied. The neutron-deficient projectile ${}^{124}\mathrm{Xe}$ is favorable to produce transtarget neutron-deficient nuclei, while ${}^{136,144}\mathrm{Xe}$ shows great advantages of cross sections for producing neutron-rich nuclei in the proton pick-up channel. Furthermore, the influence of entrance angular momentum on the charge equilibration process is investigated. It is found that in a low angular momentum channel the more profound reconstruction of initial nuclei is noticed rather than peripheral collisions. We predict the production cross sections of several neutron-rich nuclei in the reactions ${}^{136,144}\mathrm{Xe}+{}^{160}\mathrm{Gd}, {}^{136,144}\mathrm{Xe}+{}^{170}\mathrm{Er}$, and ${}^{136,144}\mathrm{Xe}+{}^{186}\mathrm{W}$. It is found that many unknown nuclei can be produced at the level of $\mu \mathrm{b}$ to mb.

Figure 1

Comparison of calculated production cross sections for the various projectile-like fragments (PLFs) in the reaction ${}^{136}\mathrm{Xe}+{}^{238}\mathrm{U}$ with the experimental data [13]. The experimental data are denoted by solid squares. The thin and thick lines are distributions of primary and final fragments, respectively. The incident energy $E_{\mathrm{c}.\mathrm{m}.}=636$ MeV.

Figure 2

Cross sections for producing target-like fragments (TLFs) with $Z=88–96$ in the transfer reactions ${}^{124}\mathrm{Xe}+{}^{238}\mathrm{U}$ (dashed lines), ${}^{136}\mathrm{Xe}+{}^{238}\mathrm{U}$ (dash-dotted lines), and ${}^{144}\mathrm{Xe}+{}^{238}\mathrm{U}$ (solid lines). The incident energy $E_{\mathrm{c}.\mathrm{m}.}=1.1\times V_{\mathrm{cont}}$. The circles denote the unknown nuclei.

Figure 3

(a) The PES as functions of $Z_1$ and $N_1$ of fragment 1 in the reaction ${}^{144}\mathrm{Xe}+{}^{238}\mathrm{U}$. The red line indicates the minimum trajectory in the PES. The values of the driving potential need overcoming (b) and $Q_{\mathrm{gg}}$ ($=M_{\mathrm{P}}+M_{\mathrm{T}}-M_{\mathrm{PLF}}-M_{\mathrm{TLF}}$) value (c) in the nucleon transfer process as a function of the number of transferred nucleons ($N_{\mathrm{tr}}$) in the reaction ${}^{144}\mathrm{Xe}+{}^{238}\mathrm{U}$. $M_{\mathrm{P}},M_{\mathrm{T}},M_{\mathrm{PLF}}$, and $M_{\mathrm{TLF}}$ are the masses of projectile, target, PLF, and TLF, respectively. The squares, solid squares, circles, and solid circles denote pure proton stripping, pure proton pick-up, pure neutron stripping, and pure neutron pick-up process, respectively. The lines are used to guide the eye.

Figure 4

(a) Yield distributions of total primary fragments as a function of their $N/Z$ ratio in the reaction ${}^{124}\mathrm{Xe}+{}^{238}\mathrm{U}$ for entrance angular momentum $J=10$ (dashed line), $J=140$ (dash-dotted line), and weighted average of different $J$ (solid line). (b) Yield distributions of primary fragments as a function of their $N/Z$ ratio in the reaction ${}^{144}\mathrm{Xe}+{}^{238}\mathrm{U}$ for entrance angular momentum $J=10$ (dashed line), $J=150$ (dash-dotted line), and weighted average of different $J$ (solid line). (c) Yield distributions of primary TLFs as a function of their $N/Z$ ratio in the reaction ${}^{124}\mathrm{Xe}+{}^{238}\mathrm{U}$ and ${}^{144}\mathrm{Xe}+{}^{238}\mathrm{U}$. The $N/Z$ ratio is discretized by 0.05. The incident energy $E_{\mathrm{c}.\mathrm{m}.}=1.1\times V_{\mathrm{cont}}$. The lines are used to guide the eye.

Figure 5

Calculated cross sections for producing isotopes of elements with $Z=60–63$ in reactions ${}^{136,144}\mathrm{Xe}+{}^{160}\mathrm{Gd}$. The incident energies ($E_{\mathrm{c}.\mathrm{m}.}$) for the reactions ${}^{136}\mathrm{Xe}+{}^{160}\mathrm{Gd}$ and ${}^{144}\mathrm{Xe}+{}^{160}\mathrm{Gd}$ are 353 and 338 MeV, respectively. The circles denote the unknown nuclei.

Figure 6

Calculated cross sections for producing isotopes of elements with $Z=64–67$ in reactions ${}^{136,144}\mathrm{Xe}+{}^{170}\mathrm{Er}$. The incident energies ($E_{\mathrm{c}.\mathrm{m}.}$) for the reactions ${}^{136}\mathrm{Xe}+{}^{170}\mathrm{Er}$ and ${}^{144}\mathrm{Xe}+{}^{170}\mathrm{Er}$ are 372 and 356 MeV, respectively. The circles denote the unknown nuclei.

Figure 7

Calculated cross sections for producing isotopes of elements with $Z=70–73$ in reactions ${}^{136,144}\mathrm{Xe}+{}^{186}\mathrm{W}$. The incident energies ($E_{\mathrm{c}.\mathrm{m}.}$) for the reactions ${}^{136}\mathrm{Xe}+{}^{186}\mathrm{W}$ and ${}^{144}\mathrm{Xe}+{}^{186}\mathrm{W}$ are 406 and 389 MeV, respectively. The circles denote the unknown nuclei.