Dynamic Isovector Reorientation of Deuteron as a Probe to Nuclear Symmetry Energy

We present the calculations on a novel reorientation effect of deuteron attributed to isovector interaction in the nuclear field of heavy target nuclei. The correlation angle determined by the relative momentum vector of the proton and the neutron originating from the breakup deuteron, which is experimentally detectable, exhibits significant dependence on the isovector nuclear potential but is robust against the variation of the isoscaler sector. In terms of sensitivity and cleanness, the breakup reactions induced by the polarized deuteron beam at about $100\mathrm{MeV}/\mathrm{u}$ provide a more stringent constraint to the symmetry energy at subsaturation densities.

Figure 1

(a) The schematic view of a deuteron induced peripheral collision on a heavy target ${}^{124}\mathrm{Sn}$. The lower panels show the isovector forces (b) and the local density (c) experienced by $n$ (squares) and $p$ (circles) as a function of time at various impact parameters. The Coulomb force on $p$ is plotted (dashed lines) in panels (b).

Figure 2

The distribution of the correlation angle $\alpha$ in $100\mathrm{MeV}/\mathrm{u}$ $\overrightarrow{\mathrm{d}}+{}^{124}\mathrm{Sn}$. (a) Calculations using MSL0-like Skyrme interactions with $\gamma =0.5$ and 2.0 for the randomly oriented (curves) and pre-oriented (symbols) deuteron beams. (b) Calculations using MSL0-like Skyrme interactions at impact parameters $b=6.0,\hspace{0.17em}7.0\hspace{0.17em}\mathrm{a}\mathrm{n}\mathrm{d}\hspace{0.17em}7.5\hspace{0.17em}\mathrm{f}\mathrm{m}$. (c) Calculations using 7 real Skyrme interactions. See text for detailed discussion.

Figure 3

(a) The logarithmic spectra of $\cos \alpha$ in $\overrightarrow{\mathrm{d}}{+}^{124}\text{Sn}$ with $b=7\mathrm{fm}$ at $100\mathrm{MeV}/\mathrm{u}$ for various $\gamma$ and corresponding fitted quadratic functions, (b) the linear coefficient $a_1$ as a function of $\gamma$. See text for detailed discussions.

Figure 4

(a) The correlation plot of the kinetic energy and the outgoing polar angle of the produced nucleons, (b) the multiplicity spectra of total nucleons (b1), protons (b2), and neutrons (b3) with (solid bars) and without (open bars) the kinetic energy cut.