Comparison of the differential cross-sections for. pi. /sup -/p. -->. eta 'n and. pi. /sup -/p. -->. eta n at 8. 45 GeV/c

The ratio R of the differential cross sections for ..pi../sup -/p eta'n and ..pi../sup -/p eta n was measured with high statistics and small systematic errors at 8.45 GeV/c. R is generally interpreted as the relative content of nonstrange, ground-state quarks in eta' and eta. It is found that R decreases with increasing t; however, extrapolation to t = 0 gives R(0) = 0.672 +- 0.032 (statistical) +- 0.047 (systematic) for the dominant spin flip cross sections, and R(0) = 0.500 +- 0.085 +- 0.035 for the spin nonflip, in excellent agreement with results at higher energy.