Measurement of thep−pElastic-Scattering Spin ParameterCLLat 11.75 GeV/cforθc.m.=48°−90°

Results are presented of a measurement of the proton-proton elastic-scattering spin parameter $C_{\mathrm{LL}}=(L,L;0,0\mathrm{})\mathrm{}$ at 11.75 GeV/c and ${\theta }_{\mathrm{c}.\mathrm{m}.\mathrm{}}=48\mathrm{}°-90\mathrm{}°$. The value of $C_{\mathrm{LL}}$ is nearly constant and is approximately -0.16 in this angular region. This behavior is consistent with only one of the many models proposed describing the interaction via the hard scattering of two quarks.