Forty-seven charm events have been observed in an exposure of the SLAC Hybrid Facility bubble chamber to a 20-GeV backward-scattered laser beam. Thirty-seven events survive all the necessary cuts imposed. Based on this number the total charm cross section is calculated to be ${63}_{-28\mathrm{}}^{+33\mathrm{}}$ nb.

• Received 2 May 1983

DOI:https://doi.org/10.1103/PhysRevLett.51.156