B. Haber

Production of slow protons in the inclusive reactions p(π+) + n → pslow + x AT 195 GeV/c

Abstract The inclusive reactions pn → p s + x and π + n → p s + x at incident momentum of 195 GeV/ c have been studied in an exposure of the Fermilab 30 inch deuterium filled bubble chamber to a mixed ( π + , p) beam. Analysing the t and M 2 dependence of our data within the framework of triple-Regge models we conclude that pion exchange yields a dominating contribution. Comparing our data with the pp results we conclude that isoscalar Regge exchange, ω, is much larger than isovector, ϱ, Regge exchange. We observe significant leading π − emission from the recoiling mass x, comparable to that observed in on-mass-shell π − p → π − experiments. This verifies our conclusions about pion-exchange dominance in the above reactions.

Study of the reactions K−n → Λπ− and K−n → Σoπo at 3 GeV/c

Abstract The total and differential cross sections of the reactions K − n → Λπ − , K − n → Σ o π − and K − n → Σ − π o , as well as the Λ polarization in the first reaction, have been measured at an incident K − momentum of 3 GeV/ c .

Charged multiplicity distributions in pd and π+d interactions at 195 GeV/c

Abstract Topological inelastic cross-sections and average multiplicities for pd and π + d interactions at 195 GeV/c, are obtained from an exposure of the NAL 30″ proportional wire chamber-bubble chamber hybrid system to a positive π + /p beam. We find that 〈 n c 〉 pn = 7.67 ± 0.25, and 〈 n c 〉 π + n = 7.56 ± 0.30, yielding a negative multiplicity difference between pn and pp of 0.50 ± 0.14, and that σ n (pp) is approximattely interleaved between σ n −1 (pn).

Inclusive particle spectra in p(π+)n interactions at 195 GeV/c☆

Abstract We present results on single-particle inclusive distributions in p( π + )n reactions from a Fermilab experiment using the hybrid 30″ bubble chamber and PWC facility. Distributions in rapidity, y , Feynman x and p 2 T for π + and π − are presented and compared with other experiments. The effects of different targets and projectiles (neutrons, protons and pions) on the distributions are demonstrated and discussed in terms of projectile and target fragmentation. The average transverse momentum 〈 P T 〉 is studied as a function of x , y and multiplicity.

Photoproduction of ω - mesons from 1.2 to 8.2 GeV

Abstract The reaction γ p→ ω p was studied between 1.2 and 8.2 GeV using positron annihilation radiation. Assuming σ ∝ C OPE · E γ −2 + C DIFF we obtain for the Pomeron exchange cross section (1.5 ± 0.3) μb.

Baryon exchange in the reactions K−n → Yπ− at 3 GeV/c

At 3 GeV/c, the total and differential cross sections of the reactions K−n → Yπ− have been determined for nine S = −1 baryonic states. Backward peaks associated with a dip near u = −0.2 are observed in many cases. They have been interpreted, for the isospin-zero Y-states, in terms of a proton-exchange mechanism. The backward peaks in the reactions K−n → Λπ− and K−n → Σoπ− have been more quantitatively related to the backward πN → Nπ differential cross sections at the same energy. This comparison leads to the conclusion, that the first reaction is dominated by nucleon exchange, whereas the second one requires a more complex exchange mechanism.

Δ++(1236) Δ−(1236) production in pn collisions at 6.98 GeV/c

The reaction pn → Δ++Δ− with σ = 1.1 ± 0.2 mb is studied at 6.98 GeV/c. Comparison with the reactions pp → ΔΔ and pp → ΔΔ at different incident momenta shows that their cross section behaves like Plab−2.5±0.3, consistent with one-pion exchange. The production and decay of Δ++Δ− at small momentum transfer agrees with the OPE model with sharp cut-off at R = 1.3 fm. The decay correlations are also compared with some quark-model predictions.

Photoproduction of ϱ0 and ω in γd interactions at 4.3 GEV

Abstract Coherent photoproduction of ϱ 0 and ω at E γ = 4.3 GeV is observed. The ratios ϱ 0 d/ ω d and ϱ 0 d/ ϱ 0 p are discussed and compared with theoretical predictions. By comparing our data with total photoabsorption cross sections we determine the direct vector meson-photon coupling to be γ ϱ 2 /4 π = 0.29 ± 0.06. With this value we find the VDM relations between photoproduction and Compton scattering well satisfied.

FOUR- AND FIVE-PION PRODUCTION IN pp COLLISIONS AT 6.92 GeV/c.

Abstract We have studied pp interactions at 6.92 GeV/c incident lab momentum leading to six and more charged non-strange particles. The values for the six- and eight-prong cross sections were found to be 1.08 ± 0.07 and 0.02 ± 0.01 mb respectively. The behaviour of the normalized average matrix-element squared as a function of incident momentum for the six- and seven-body final states and the predictions of the quark additive model have been investigated. The c.m. angular distributions and the longitudinal and transverse momenta distributions for the outgoing particles are presented and discussed. The production of isobars and mesons has been investigated. Cross sections for the production of Δ++ (1236), Δ−(1236), N∗(1525) and ω-meson are presented. The angular correlation parameters for the multi-pion systems are given.

Evidence for B(1220) production in an analysis of the reaction K− d→psΛπ+π−π−πo at 3 GeVc

Abstract In an analysis of the reaction K − n →Λ4π at 3 GeV c we find evidence for the production of the B(1220) resonance, mainly decaying in ωπ. For the mass and width we find (1236 ± 15) MeV c 2 and (132±20) MeV c 2 respectively. The cross section for the reaction K−n→Λ+B(1220) is found to be (102±26)μb.