Determination of theS-WaveI=0π−πPhase Shifts from Threshold to 0.96 GeV

The $I=0\mathrm{}$ $S$-wave $\pi -\pi$ phase shifts have been determined in the $\pi -\pi$ mass range from threshold to 0.96 GeV by use of data from the reaction ${\pi }^{+}p\to p{\pi }^{+}{\pi }^0{\pi }^0$ at 8 GeV/c. The resulting phase shifts confirm the phase shifts determined from previous ${\pi }^{+}{\pi }^{-}\to {\pi }^{+}{\pi }^{-}$ data above 0.7 GeV, but are significantly below the accepted phase shifts below 0.6 GeV where our phase shifts are now consistent with current-algebra predictions.