Determination of the Space-Time Extension of Centrally Produced Hadronic Matter Using the Intensity Interferometer Technique inppInteractions at 28.5 GeV/c

We have measured in the central region, the ratio of negative pion pairs to that of negative-positive pion pairs as a function of the Kopylov variables. A correlation was observed. From the shape of the correlation function we determined the radius $r$ and life-time $\tau$ of the centrally produced hadronic matter parallel and perpendicular to the collision axis to be $r_{\parallel }={0.73}_{-0.11\mathrm{}}^{+0.10\mathrm{}}$ fm, $r_{\perp }={1.65}_{-0.99\mathrm{}}^{+3.56\mathrm{}}$ fm, and ${\tau }_{\parallel }=\left({1.97}_{-0.56\mathrm{}}^{+0.57\mathrm{}}\right)\times {10}^{-24\mathrm{}}$ sec.