Search for fractionally charged nuclei in high-energy heavy-ion collisions

An experiment was performed to search for fractionally charged nuclei with charge $Z$, $14<~Z<~18$, produced as projectile fragments of 1.8-GeV/nucleon ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ar}$. Analysis of 1.75 × ${10}^5$ projectile fragments yielded no fragments with charges differing from integer values by more than $\pm \frac{1}{3}e$. This experiment places limits (90% C.L.) on the relative abundance of fractionally charged projectile fragments with residual charge $+\frac{1}{3}e(-\frac{1}{3}e)$ of less than 1.8 × ${10}^{-4\mathrm{}}$ (2.3 × ${10}^{-4\mathrm{}}$.