Analyzing power for proton elastic scattering from the neutron-rich ${}^6\mathrm{He}$ nucleus

Vector analyzing power for the proton-${}^6\mathrm{He}$ elastic scattering at 71 MeV/nucleon has been measured for the first time, with a newly developed polarized proton solid target, which works at a low magnetic field of 0.09 T. The results are found to be incompatible with a $t$-matrix folding model prediction. Comparisons of the data with $g$-matrix folding analyses clearly show that the vector analyzing power is sensitive to the nuclear structure model used in the reaction analysis. The $\alpha$-core distribution in ${}^6\mathrm{He}$ is suggested to be a possible key for understanding the nuclear structure sensitivity.

Figure 1

Schematic of the experimental setup, which includes the polarized proton solid target.

Figure 2

Cross section and vector analyzing power for the $p\text{−}{}^6\mathrm{He}$ elastic scattering at 71 MeV/nucleon (filled circles), together with cross-section data in Ref. [4] (open circles) and data for ${}^6\mathrm{Li}$ [18] (triangles) targets. The dotted lines are a $t$-folding calculation in Ref. [20]. Results of 6BF calculations with harmonic oscillator (dashed), WS with (solid), and without halo (dot-dashed) single-particle wave functions are shown.

Figure 3

Present data compared with the cluster-folding calculations. Solid, dashed, and dot-dashed lines represent calculations with full, $V_{\mathit{pn};\ell s}=0$, and $V_{\mathit{pn};\ell s}=V_{\mathit{pn};\mathrm{central}}=0$ interactions, respectively. Data for the $p\text{−}{}^4\mathrm{He}$ scattering [22] (squares) are also shown.