A search for charged particles originating from the interactions of 300 GeV/c protons in emulsion nuclei

The associated production of charmed particles by the interactions of 300 GeV/ c protons with complex nuclei has been sought using nuclear emulsions. The failure to observe any candidates for this process among some 60,000 interactions investigated implies, provided charmed particles lifetimes are in the range 10 −12 to 10 −14 s, a cross section for their associated production by the interactions of 300 GeV/ c protons with nucleons of less than 1.5 microbarns at a 90% confidence level.