A study of 205-GeV/c ${\pi }^{-}p$ interactions has been made with a 48 800-picture exposure in the bare Fermilab 30-inch hydrogen bubble chamber. The average number of charged particles produced per inelastic interaction is 7.99±0.06. The elastic cross section is 3.18±0.13 mb and the total cross section is 24.19±0.44 mb. The inclusive cross sections for neutral-particle production are: $\sigma \left(\gamma \right)=171.3\mathrm{}\pm 15.3$ mb, $\sigma \left(K_S^0\right)=3.64\mathrm{}\pm 0.61$ mb ($x<\mathrm{}0.3\mathrm{}$), $\sigma \left(\Lambda \right)=1.71\mathrm{}\pm 0.34$ mb ($x<\mathrm{}0.3\mathrm{}$), and $\sigma \left(\overline{\Lambda }\right)=0.59\mathrm{}\pm 0.23$ mb ($x<\mathrm{}0.1\mathrm{}$). The average number of ${\pi }^0\text{'}\mathrm{s}$ produced per inelastic collision is consistent with a linear rise with the number of charged particles, and about equal to the number of produced ${\pi }^{-}$ or ${\pi }^{+}$. The average number of $K^0\text{'}\mathrm{s}$, $\Lambda \text{'}\mathrm{s}$, and $\overline{\Lambda }\text{'}\mathrm{s}$ is consistent with very little dependence on the number of charged particles. General characteristics of neutral-particle production are presented and compared with other experiments. For each topology the produced neutral energy is $\sim \frac{1}{3}$ of the incident energy.

• Received 6 December 1976

DOI:https://doi.org/10.1103/PhysRevD.15.3163