Inclusive reaction ${}^{93}\mathrm{Nb}$($\vec{p}$,$\alpha$) at an incident energy of 160 MeV

The inclusive ${}^{93}\mathrm{Nb}$($\vec{p},\alpha$) reaction to the continuum was investigated at an incident energy of 160 MeV. Emission-energy angular distributions for cross sections as well as analyzing powers were explored. A range of scattering angles from 15${}^{\circ }$ to 60${}^{\circ }$ (lab.) was covered and $\alpha$-particle emission energies from $\approx$30 MeV to the kinematic limit were measured. As in our earlier work, the experimental distributions were compared with a multistep direct theory combined with a knockout reaction mechanism as the terminating step in the $\alpha$-particle emission. Reasonable agreement between the theoretical predictions and the experimental double-differential cross section and analyzing-power angular distributions were obtained.

Figure 1

Double-differential cross sections (a) and analyzing power (b) as a function of scattering angle $\theta$ for the ${}^{93}\mathrm{Nb}$($p$,$\alpha$) reaction at an incident energy of 160 MeV and an $\alpha$-outgoing energy of 158 MeV. Theoretical calculations assuming a knockout mechanism are denoted by solid lines and those using a pickup mechanism by dashed lines.

Figure 2

The same as in Fig. 1 for $E_{\mathrm{out}}=130$ MeV.

Figure 3

Double-differential cross sections [(a)–(d)] and analyzing power [(e)–(h)] as a function of scattering angle $\theta$ for the ${}^{93}\mathrm{Nb}$($p$,$\alpha$) reaction at an incident energy of 160 MeV and various $\alpha$-particle outgoing energies $E_{\mathrm{out}}$ as indicated. Theoretical cross-section calculations for one step ($---$), two steps ($·····$), and three steps ($-·-·-$) are shown, with the sums of the contributions plotted as continuous curves. The experimental analyzing-power distributions are compared with theoretical calculations for a one-step reaction ($---$), a one-step plus a two-step reaction ($·····$), and a one- plus two- plus three-step reaction (solid lines). The experimental data are averaged over emission energy bins of 4 MeV and statistical error bars are shown where those exceed the symbol size.