Measurement of Pion Proton Deep Elastic Scattering at 13.7 and 19.4 GEV Center of Mass Energies.

Differential cross sections for (pi)('(+OR-))p elastic scattering are measured at Fermilab using 100 and 200 Gev/c secondary beams incident on a liquid hydrogen target. The final state 3-momenta of the pion and proton are measured with magnetic spectrometers employing proportional wire chambers. A differential cerenkov counter in the beam and a threshold cerenkov counter in the pion spectrometer provide particle identification. Cross sections are measured for the following kinematic regions of center of mass energy SQRT.(s(' )and squared 4-momentum transfer t:. (pi)('(+OR-))p, 0.5 < -t < 2.5 (Gev/c)('2), SQRT.(s = 13.7 Gev. (pi)('+)p, 0.9 < -t < 3.5 (Gev/c)('2), SQRT.(s(' )=(' )19.4 Gev. (pi)('-)p, 0.9 < -t < 11. (Gev/c)('2), SQRT.(s(' )=(' )19.4 Gev. The (pi)('-)p results at SQRT.(s = 19.4 Gev show that this differential cross section has a relative minimum at -t (TURNEQ) 4.1 (Gev/c)('2) and a secondary maximum at -t (TURNEQ) 5.3 (Gev/c)('2). The relative minimum separates a low -t region where the differential cross section has an exponential slope (TURNEQ) -4. (Gev/c)('-2) from a high -t region with slope (TURNEQ) -.4 (Gev/c)('-2). The four cross sections measured in this experiment, together. with the results of other experiments, indicate an approximate. independence from charge and energy in the region SQRT.(s > 6 Gev for pion proton elastic scattering.