We have measured the intensities of $2p-1s$ pionic x-ray transitions in ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$, ${}_{}{}^9{}_{}{}^{}\mathrm{Be}$, ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$, and ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ using an absolute-efficiency technique. A pion-cascade calculation which was constrained to reproduce the observed yields predicted population probabilities for the mesonic levels and gave values for the strong-interaction level widths. The $2p$-level broadenings are 0.015 ± 0.005 eV for ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$, 0.16 ± 0.03 eV for ${}_{}{}^9{}_{}{}^{}\mathrm{Be}$, 2.1 ± 0.6 eV for ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$, and 12 ± 4 eV for ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$. Comparisons are made with results obtained by others and with predictions based upon a semiphenomenological optical potential. Empirical capture schedules for ${\pi }^{-}$ in ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$ and ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ are also presented.

• Received 7 September 1971

DOI:https://doi.org/10.1103/PhysRevC.5.690