Study of the Okubo-Zweig-Iizuka--rule--violating reactions. pi. /sup +/n. -->. phip and. pi. /sup +/p. -->. phi. delta. /sup + +/ at 10 GeV/c

We have measured the cross sections for the Okubo-Zweig-Iizuka--rule--violating reactions ..pi../sup +/n..-->..phip and ..pi../sup +/p..-->..phi..delta../sup + +/ at 10 GeV/c using the large-aperture-solenoid spectrometer at the Stanford Linear Accelerator Center. We measure the total cross sections for these two reactions to be 179 +- 72 nb for the phip reaction and 172 +- 75 nb for the phi..delta../sup + +/ reaction. Both of these cross sections are consistent with the hypothesis of the phi being produced solely by its nonstrange-quark component as determined from the octet-singlet mixing angle resulting from application of the Gell-Mann--Okubo mass formula to the vector-meson nonet. These data are thus inconsistent with an ideally mixed phi meson.