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We have studied nonstrange p¯−p interactions observed in 7000 pictures of the 80-in. Brookhaven National Laboratory hydrogen bubble chamber exposed to an antiproton beam with a momentum of 6.94 BeVc. The total cross section was measured to be 58.7±2.8 mb, and the elastic interaction cross section 14.2±1.2 mb. The elastic differential cross section for four-momentum transfers (−t)≤0.3 (BeVc)2 is well described by the exponential form dσeldt=(dσdt)t=0ebt, where b=13.1±1.1 (BeVc)−2. The single-pion production cross section is 4.0±0.9 mb. This channel proceeds 70% through resonance formation. N*(1238) isobar and anti-isobar formation dominates pion production in four- and six-pronged events; the double-isobar formation cross section in the final state pπ+p¯π− is 1.35±0.2 mb. Isobar production was observed to be consistent with the predictions of a dominant one-particle-exchange process. The pion-annihilation process, which has a cross section of 25±5 mb, shows substantial pion resonance formation.
We measured the differential cross section for p̄p and pp elastic scattering in the momentum-transfer range 0.01 <| t | < 1.0 GeV 2 at the CERN Intersecting Storage Rings with center-of-mass energy s = 52.8 GeV . Fitting the differential cross section with an exponential [ A exp ( bt )], we found b p p = 13.92 ± 0.59 GeV −2 for | t | < 0.05 GeV 2 , whilst for | t | > 0.09 GeV 2 , b p p = 10.68 ± 0.26 GeV −2 . Using the optical theorem, we obtained for the total cross section σ tot ( p p)= 44.86 ± 0.78 mb and, by integrating the differential cross section, we obtained for the total elastic cross section σ el ( p p) = 7.89 ± 0.28 mb . Calculations of σ tot combining elastic-rate and total-rate measurements are also given. All of these measurements were also performed for pp scattering at the same energy, and the results for both reactions are compared.
Results on charged particle production in pp̄ collision at s 1 2 = 540 GeV are presented. The data were obtained at the CERN pp̄ collider using the UA1 detector, operated without magnetic field. The central particle density is 3.3 + - 0.2 per unit o pseudo-rapidity for non-diffractive events. KNO scaling of the multiplicity distributions withresults from ISR energies is observed.