We used nuclear track detectors to construct the trajectories of interactions and to measure with high resolution the charge of the beam and of heavy nuclear fragments produced in interactions. A null result of our search for fractional charge states in high-energy fragments with charges 8≤Z≤13 produced in collisions of 14.5A GeV ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$ nuclei with Pb and Cu targets leads us to conclude that the upper limits for the probability of production of a fragment with charge 23/3, 25/3, 26/3 28/3 29/3, 31/3 32/3, 34/3, 35/3, 37/3, or 38/3 charge unit in Pb and Cu at 90% confidence level are 1.9×${10}^{\mathrm{-}4}$ and 3.9×${10}^{\mathrm{-}4}$, respectively. We set a similar limit on the relative number of particle-stable fragments with 8≤Z≤14 created in the central rapidity region.

• Received 19 July 1991

DOI:https://doi.org/10.1103/PhysRevC.44.1672