[en] The article discusses bubble chambers for the investigation of strong interactions at SPS energies. It specifies the reactions to be observed, primarily kaon reactions with other elementary particles. It then gives the technical aspects of both the Big European Bubble Chamber (BEBC) and the European Hybrid Spectrometer (EHS)

[en] The isospin I=3/2K^-π^- inelastic scattering cross section is determined from the reactions K^-p→Δ⁺⁺(K+pions)^-- at 4.2 GeV/c incident K^- momentum, using a Chew-Low extrapolation method. The available statistics also allowed a determination of the cross sections for individual K^-π^- reactions by this method. The total inelastic K^-π^- scattering cross section is found to increase almost linearly with K^-π^- mass from <0.1 mb at 0.9 GeV to 2.3 mb at 1.5 GeV. Below 1.3 GeV only the reactions K^-π^-→(Kππ)^-- contribute to the inelastic cross section; higher multiplicity K^-π^- interactions start to play a role above this mass. (Auth.)

[en] An analysis is presented of the reaction K^-p → anti K⁰π^-p at 4.2 GeV/c incident momentum, using analytical techniques in fully dimensional phase space. This method allows to isolate the contributions of the 0⁺, 1^- and 2⁺ (Kπ) partial waves in various helicity states, as well as their interferences. Separating well-understood contributions from the rest, the method is particularly useful for the detection of small effects (ca 1% of the total final-state cross section) not visible in the mass distributions: (i) small cross-section contributions of 3^- (Kπ) partial waves, K*(1780), are unambiguously isolated; (ii) 3.5 sigma evidence is given for Σ(1480) in the (p anti K⁰) system; (iii) effects due to a second Kπ P-wave or the possible presence of a doubly peripheral mechanism are discussed. The method furthermore allows simultaneous treatment of the (Kπ) partial waves, (pπ) partial waves and their interferences and of a Σ(1765) signal (with spin ⁵/₂). While interferences within the (Kπ) and within the (pπ) systems are strongly determining the corresponding distributions, no interference between these systems is needed. (orig.)

[en] The reactions K^-p → π^-Σ⁺(1385) and K^-p → π⁺Σ^-(1385) are studied at 4.2 GeV/c incident momentum using data from a high statistics bubble chamber experiment corresponding to approximately 80 events/μb. The total and differential cross sections are presented. Amplitude analyses are performed and the complete Σ^+-(1385) helicity spin density matrices are extracted. The results are compared with the predictions of the additive quark model and exchange degeneracy. A substantial cross section is observed for the reaction K^-p → π⁺Σ^-(1385) in the forward direction, which implies exotic meson quantum numbers in the t-channel. One possible interpretation of this process provides an explanation for the small but significant violations of the additive quark model predictions observed in the reaction K^-p → π^-Σ⁺(1385) at low four-momentum transfer. In the backward direction unnatural parity exchange is shown to give a larger contribution to K^-p → Σ^-(1385)π⁺ than natural parity exchange. (Auth.)

[en] A partial-wave analysis of the low-mass (π⁺π^-p) system produced in the reaction K^-p→K^-(π⁺π^-p) at 4.2 GeV/c incident momentum is performed in order to study the two (π⁺π^-p) enhancements around 1500 and 1700 MeV. It is found that the low-mass (π⁺π^-p) system can be described using the spin-parity states Jsup(P)=1/2⁺, 3/2^- and 5/2⁺ only. In the 1500 MeV region contributions are observed from the 1/2⁺ wave decaying into pepsilon and the 3/2^- wave decaying into Δ⁺⁺π^-; in the 1700 MeV region contributions are found from the 1/2⁺ wave decaying into Δ⁺⁺π^-, the 3/2^- wave decaying into pepsilon, and the 5/2⁺ wave decaying into pepsilon. (Auth.)

[en] Properties of Σ^+-(1385) inclusively produced in 4.2 GeV/c K^-p interactions are studied. Inclusive cross sections are presented together with differential cross sections as functions of x and psub(t)² for both Σ⁺(1385) and Σ^-(1385). The complete density matrix for Σ⁺(1385) production at small momentum transfer is studied as a function of t and of recoil mass MM². Substantial agreement with the predictions of the additive quark model is found. The Σ⁺(1385) production in the target fragmentation region is studied in the framework of the triple-Regge model. (Auth.)

[en] The inclusive production of Σ⁺ in K^-p interactions at 4.2 GeV/c has been studied. Both the target fragmentation of the proton into Σ⁺ and the beam fragmentation of the kaon into Σ⁺ have been analyzed with a triple-Regge model. In the p(anti sigma)⁺-channel, an effective exchange trajectory has been obtained which lies between the K and K(890) trajectories. For the K(anti sigma)⁺-channel, a trajectory is found which may be interpreted as a Δ-tracjectory lowered by one half

[en] A partial-wave analysis and an isospin analysis are presented of the (anti Kππ)^- systems produced in the reactions K^-p→K^-π^-π⁺p and K^-p→anti K⁰π^-π⁰p using the high-statistics bubble-chamber data at 4.2 GeV/c. The energy dependence of Jsup(P)=1⁺ waves is investigated in a comparison with results at higher energy. The dominant 1⁺0+(K*π) with its maximum in the Q₂(1.4 GeV) region is an almost pure I=1/2 state. The energy dependence of 1⁺0+(K*π) at low masses is consistent with pomeron exchange while at higher masses (including the Q₂ region) other natural exchanges are involved. The 1⁺1+(Krho) has its maximum at about 1.3 GeV. The relative phase between these two 1⁺ states is consistent with Q₁-Q₂ contributions to the 1⁺ state. Properties of the Q resonances are obtained in a fit of a two-resonance model to the 1⁺ data. There is no clear evidence for the O^- resonance seen at SLAC. (Auth.)

[en] The inclusive production of μ⁺ in K^-p interactions at 4.2 GeV/c has been studied. Both the target fragmentation of the proton into μ⁺ and the beam fragmentation of the kaon into μ⁺ have been analyzed with a triple-Regge model. In the pμ-bar⁺ channel an effective exchange trajectory has been obtained which lies between the K and K(890) trajectories. For the K^-μ-bar⁺ channel a trajectory is found which may be interpreted as a δ trajectory lowered by one-half. (author)

[en] Partial wave analysis of the anti K⁰π⁺π^- system produced in the charge exchange reaction K^-p→(anti K⁰π⁺π^-)n at 4.2 GeV/c has been performed both as a function of Kππ mass and of t. The 1⁺S wave forms the largest contribution to the Kππ system and peaks at roughly the same mass as the Q in diffractive Kππ production. The polarization properties of the 1⁺S (K*π) and 1⁺S (Krho) waves differ from those of the diffractive 1⁺ wave. There is some evidence for a resonance contribution to 1⁺S (K*π). The strong 2⁺ wave is identified with the K*(1420) and the Krho/K*π decay branching ratio determined to be 0.36 +- 0.10. An enhancement with spin-parity 1^- is observed under the K*(1420). (Auth.)