We present the first observation of the all hadronic decay of $t\overline{t}$ pairs. The analysis is performed using $109{\mathrm{pb}}^{-1\mathrm{}}$ of $p\overline{p}$ collisions at $\sqrt{s}=1.8\mathrm{}\mathrm{TeV}$ collected with the Collider Detector at Fermilab. We observe an excess of events with five or more jets, including one or two $b$ jets, relative to background expectations. Based on this excess we evaluate the production cross section to be in agreement with previous results. We measure the top mass to be $186\pm 10\pm 12\mathrm{GeV}{/c}^2$.

• Received 25 March 1997

DOI:https://doi.org/10.1103/PhysRevLett.79.1992