We measured the amplitude for the CP-symmetry-conserving decay KS0 → π+π-π0 in an experiment at Fermilab. This decay manifests itself as a time dependent charge asymmetry in the inteference between the coherent KS and KL decays. We collected π+π-π0 decays between 0.6 and 7.6 KS Lifetimes from the production target using a detector that consisted of a magnetic spectrometer and a lead glass electromagnetic. KS0 → π+π- decays that were collected simultaneously were used for normalization. The ratio p+-0 of the CP-conserving KS amplitude to the KL amplitude is found to be: •p+-0• = 0.035+0.019-0.011 (stat.) ±0.004 (syst.), with a phase Øp=-59°±48°. This yields a branching ratio of (3.9 +5.4-1.8(stat.) +0.9-0.7 (syst.)) × 10-7.
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We would like to acknowledge the help of E Cush-man, R. Handler, C. James, U. Joshi, E. Kneedler, O.E. Overseth, A. Pal, M. Sheaff, and M. Shupe in the early stages of the experiment; L. Pondrom for the loan of the MWPC system; and the staffs of the Fermilab Experimental Areas and Computing Departments for assistance at all stages. This work was supported in part by the National Science Foundation and the U. S. Department of Energy.