Semi-inclusive spectra of ${\pi }^{\pm }$, $K^{\pm }$, and p have been measured near midrapidity for central collisions of 14.6A-GeV/c ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$ with ${}_{}{}^{197}{}_{}{}^{}\mathrm{Au}$ nuclei. The invariant cross sections are all well fit by exponential distributions in transverse mass, within the measured ranges. The π and K cross sections can also be fit by Boltzmann distributions. From integrated yields, at midrapidity, the kaon/pion yield ratios are (19.2±3)% for $K^{+}$/${\pi }^{+}$ and (3.6±0.8)% for $K^{\mathrm{-}}$/${\pi }^{\mathrm{-}}$; the ${\pi }^{+}$/${\pi }^{\mathrm{-}}$ ratio is 1.00±0.04.

• Received 20 October 1989

DOI:https://doi.org/10.1103/PhysRevLett.64.847