Events with a Rapidity Gap between Jets inp¯pCollisions at√s=630GeV

We report a measurement of the fraction of dijet events with a rapidity gap between jets produced by color-singlet exchange in $\overline{p}p$ collisions at $\sqrt{s}=630\mathrm{}\mathrm{GeV}$ at the Fermilab Tevatron. In events with two jets of transverse energy $E_T^{\mathrm{jet}}>8\mathrm{}\mathrm{GeV}$, pseudorapidity in the range $1.8<\mathrm{}|{\eta }^{\mathrm{jet}}|<3.5\mathrm{}$ and ${\eta }_1{\eta }_2<0\mathrm{}$, the color-singlet exchange fraction is found to be $R=[2.7\pm 0.7(\mathrm{stat})\pm 0.6(\mathrm{syst}\left)\right]\%$. Comparisons are made with results obtained at $\sqrt{s}=1800\mathrm{}\mathrm{GeV}$ and with theoretical expectations.