This Letter reports measurements of the ratios of $\pi$, K, and p production at large values of transverse momentum in $\pi^- −p$ collisions. The charge ratios, such as $\frac {\pi^−} {\pi^+}$, $\frac {K^−} {K^+}$, and $\frac {\overline{p}}{p}$ are seen to be quite different from those measured in p −p collisions. These ratios are sensitive tests of hard-scattering models, and are compared with theoretical predictions. The particle ratios have also been studied as a function of center-of-mass angle ($\theta^*$) at $\theta^*$ = 90°, 77°, and 60°.
We have measured the multiplicities of particles emitted in collisions between π's and p's of 1.5 to 2.5 GeV/c momentum with He and Ne nuclei in a streamer chamber. The chamber gas served as the target as well as the detecting medium. Because of the low density and 4π solid angle of the detector, it was possible to detect nuclear fragments with energies less than 5 MeV, and to essentially count all the particles emitted in a collision. Event distributions as a function of track multiplicity were obtained as well as correlated event distributions. NUCLEAR REACTIONS He (proton or pion, fragments and pions), Ne (proton or pion, fragments and pions), E=1.5, 2.0, 2.5 BeV/c; streamer chamber gas used as target with fragment energies as low as 5 MeV. Measured multiplicities and correlations of produced particle types.
None
None
None