Measurement of theπ−p→3π0ntotal cross section from threshold to0.75GeV/c

We report a new measurement of the ${\ensuremath{\pi}}^{\ensuremath{-}}\stackrel{\ensuremath{\rightarrow}}{p}3{\ensuremath{\pi}}^{0}n$ total cross section from threshold to ${p}_{\ensuremath{\pi}}=0.75\mathrm{GeV}/c.$ The cross section near the $N(1535){\frac{1}{2}}^{\ensuremath{-}}$ resonance is only a few $\ensuremath{\mu}\mathrm{b}$ after subtracting the large $\stackrel{\ensuremath{\rightarrow}}{\ensuremath{\eta}}3{\ensuremath{\pi}}^{0}$ background associated with ${\ensuremath{\pi}}^{\ensuremath{-}}\stackrel{\ensuremath{\rightarrow}}{p}\ensuremath{\eta}n.$ A simple analysis of our data results in the estimated branching fraction $\mathcal{B}[{S}_{11}\ensuremath{\rightarrow}\ensuremath{\pi}N(1440){\frac{1}{2}}^{+}]=(8\ifmmode\pm\else\textpm\fi{}2)%.$ This is the first such estimate obtained with a three-pion production reaction.