Angle-integrated ($p$,${\pi }^{+}$) cross sections on ${}_{}{}^9{}_{}{}^{}\mathrm{Be}$, ${}_{}{}^{10}{}_{}{}^{}\mathrm{B}$, ${}_{}{}^{11}{}_{}{}^{}\mathrm{B}$, ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$, ${}_{}{}^{13}{}_{}{}^{}\mathrm{C}$, ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$, and ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ have been measured over the energy range $0.5\lesssim T_p-T_{\mathrm{threshold}}\lesssim 10$ MeV by detecting ${\mu }^{+}$ decays. By combining the present results with higher energy measurements we show that, for $1p$-shell targets, the energy dependence of the ($p$,${\pi }^{+}$) reaction from $T_{\pi }\approx 0.5 \mathrm{to}\approx 50$ MeV can be explained in terms of pion phase space and barrier penetration.

NUCLEAR REACTIONS ${}_{}{}^9{}_{}{}^{}\mathrm{Be}$($p$,${\pi }^{+}$)${}_{}{}^{10}{}_{}{}^{}\mathrm{Be}$, ${}_{}{}^{10,11}{}_{}{}^{}\mathrm{B}$($p$,${\pi }^{+}$)${}_{}{}^{11,12}{}_{}{}^{}\mathrm{B}$, ${}_{}{}^{12,13}{}_{}{}^{}\mathrm{C}$($p$,${\pi }^{+}$)${}_{}{}^{13,14}{}_{}{}^{}\mathrm{C}$, ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$($p$,${\pi }^{+}$)${}_{}{}^{15}{}_{}{}^{}\mathrm{N}$, and ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$($p$,${\pi }^{+}$)${}_{}{}^{17}{}_{}{}^{}\mathrm{O}$, $T_p-T_{\mathrm{threshold}}: 0.5-10$ MeV, measured angleintegrated cross sections.

• Received 7 May 1979

DOI:https://doi.org/10.1103/PhysRevC.20.2308