Search for Fractional Charges Produced in Heavy-Ion Collisions at 1.9 GeV/nucleon

An experiment was performed to capture fractionally charged particles produced in heavy-ion collisions and to concentrate them in samples suitable for analysis by various techniques. Two of the samples so produced have been searched, with use of an automated version of Millikan's oil-drop apparatus. The beam was ${}_{}{}^{56}{}_{}{}^{}\mathrm{Fe}$ at 1.9 GeV/nucleon, incident on a lead target. Less than one fractional charge per 1.0×${10}^4$ Fe-Pb collisions was found to be produced, and, with further assumptions, less than one per 2.0×${10}^6$ collisions.