C12(p,pn)C11Cross Section at 7.6 GeV

The absolute cross section for the ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}\mathrm{}(p,pn)\mathrm{}{}_{}{}^{11}{}_{}{}^{}\mathrm{C}$ reaction has been measured in an external beam of the Argonne zero gradient synchrotron at 8.5-GeV/c momentum (7.6-GeV protons). Proton fluxes were measured with a scintillation counter telescope, and the 20.4 min ${}_{}{}^{11}{}_{}{}^{}\mathrm{C}$ activity induced in $\frac{1}{8}$-in.-thick plastic scintillators was determined both by internal scintillation counting and by ${\beta }^{+}$-annihilation radiation counting with a NaI(T1) well crystal. A correction for the formation of ${}_{}{}^{11}{}_{}{}^{}\mathrm{C}$ by secondary particles was determined and a correction was made for the small ${\pi }^{+}$ contamination of the proton beam. The ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}\mathrm{}(p,pn)\mathrm{}{}_{}{}^{11}{}_{}{}^{}\mathrm{C}$ cross section at 7.6 GeV is 28.2 ± 0.6 mb.