Observation of the Production of Short-Lived Particles in a High-Resolution Streamer-Chamber Experiment

Short-lived particles produced in association with muons have been observed in the interactions of 350-GeV/c protons with neon in a high-resolution streamer chamber. The characteristics of these events are consistent with the expected properties of charmed particles if the average lifetime lies between ${10}^{-13\mathrm{}}$ and 2×${10}^{-12\mathrm{}}$ sec. With the assumption that the observed events are mainly $D^{\pm }$ mesons with lifetimes of approximately ${10}^{-12\mathrm{}}$ sec, the production cross section is estimated to lie between 20 and 50 μb per nucleon.