Elastic scattering and breakup of ${}^{11}\mathrm{Be}$ on deuterons at $26.9A$ MeV

The elastic scattering and breakup reactions of the halo nucleus ${}^{11}\mathrm{Be}$ on deuterons at an incident energy of $26.9A$ MeV are reported for the first time. Special attention has been paid to the determination and subtraction of the proton contaminations in the deuterated polyethylene ${\left({\mathrm{CD}}_2\right)}_n$ target (where ${\mathrm{D}}_2$ denotes ${}^2\mathrm{H}_2$). The cross sections for elastic scattering are analyzed with the systematic optical potentials of Daehnick et al. and DA1p, as well as with single-folding potentials, derived from the Jeukenne-Lejeune-Mahaux effective nucleon-nucleon interaction. An extended version of the continuum-discretized coupled-channels (XCDCC) formalism, including dynamic core excitation (DCX) effects, is applied to analyze the elastic scattering and breakup data. Comparisons of the full XCDCC calculation with that omitting DCX effects indicate that the core excitation plays a remarkable role in reproducing breakup reactions of ${}^{11}\mathrm{Be}+d$.

Figure 1

The PID using data taken by TELE0 in coincidence with light particles measured by TELE1.

Figure 2

Plot of energy vs angle for the recoil light particles in coincidence with (a) ${}^{11}\mathrm{Be}$ and (b) ${}^{10}\mathrm{Be}$ for ${\left({\mathrm{CD}}_2\right)}_n$ (color palettes) and ${\left({\mathrm{CH}}_2\right)}_n$ (black dots and triangles) targets. The calculated kinematic loci for the elastic scattering of ${}^{11}\mathrm{Be}+d$ and ${}^{11}\mathrm{Be}+p$ are shown as solid and dot-dot-dashed curves in (a), while that for the ${}^{11}\mathrm{Be}+d$ inelastic scattering to the 1.78- and 3.41-MeV resonances of ${}^{11}\mathrm{Be}$ are represented as dashed and dotted curves in (b), respectively. The dot-dashed line stands for the kinematic curve for the $n-d$ elastic scattering.

Figure 3

Angular correlation spectra for the recoil light particles and the elastic scattered (a) ${}^{11}\mathrm{Be}$, and (b) ${}^{10}\mathrm{Be}$ from the breakup reaction, respectively, on the impure ${\left({\mathrm{CD}}_2\right)}_n$ target. The definitions of kinematic curves are the same as those in Fig. 2. The area marked by dotted curves in (a) shows the cut applied for the calculation of proton contaminations. The black dot-dashed circle in (b) represents the area for the $1n$ stripping reaction from ${}^{11}\mathrm{Be}$ by the ${\left({\mathrm{CD}}_2\right)}_n$ target.

Figure 4

Excitation energy spectrum for (a) the ground state and (b) unbound excited states of ${}^{11}\mathrm{Be}$ deduced from the scattered deuterons in coincidence with ${}^{11}\mathrm{Be}$ and ${}^{10}\mathrm{Be}$, respectively. The background contributions arising from ${}^{12}\mathrm{C}$ and ${\left({\mathrm{CH}}_2\right)}_n$ have been subtracted. The dashed curve in (b) with the vertical axis on the right-hand side stands for the solid angle of TELE1.

Figure 5

Comparisons between the experimental differential cross sections (as a ratio to Rutherford) and optical model calculations for the ${}^{11}\mathrm{Be}+d$ elastic scattering at $26.9A$ MeV. The dot-dashed, dotted, as well as dashed and solid curves represent the calculations with optical potentials of DA1p, Daehnick et al. [24], as well as the folding potential generated with the JLM nucleon-nucleon interaction, with energy-dependence parameters of set I and set II, respectively.

Figure 6

Experimental and calculated elastic differential cross sections, ratio to Rutherford, for the reaction ${}^{11}\mathrm{Be}+d$ at $26.9A$ MeV.

Figure 7

Experimental and calculated breakup cross sections, as a function of the c.m. scattering angle, for the reaction ${}^{11}\mathrm{Be}+d$ at $26.9A$ MeV. The meaning of the lines is the same as in Fig. 6. The inset in (a) amplifies the region containing the experimental data.

Figure 8

Energy differential cross section, as a function of the $n-{}^{10}\mathrm{Be}$ relative energy, calculated with the XCDCC method. The solid line is the full XCDCC calculation, whereas the dashed line is the calculation omitting the ${}^{10}\mathrm{Be}+d$ excitation mechanism. The arrow indicates the excitation energy of the $n+{}^{10}\mathrm{Be}\left(2^{+}\right)$ threshold.