T. Meyer

Hyperon production in pp interactions at √s = 53 and 62 GeV

Abstract Inclusive measurements of Λ 0 , Λ 0 , Ξ − , Σ(1385) ± ) production in the forward direction at the CERN intersecting storage rings are presented. A signal for simulataneous Λ 0 Λ 0 production is also observed with total x > 0.6, 2.3 Λ Λ GeV and with a cross section of (1.7 ± 0.2) μb.

Evidence for Λc+ in inclusive pp → (Λ0π+π+π−) + X and pp → (K−π+p) + X at √s = 53 and 62 GeV

Abstract A search for the charmed baryon, Λ c + , has been carried out in inclusively, measured Λ 0 π ± π + π − and K − π ± p final states with longitudinal x > 0.75 in an experiment at the CERN intersecting storage rings. An effect with invariant mass near 2.3 GeV is observed in Λ 0 π + π + π − with cross section times branching ratio Bσ = (2.8±1.0) μ b; similar effect is observed in K − π + p with Bσ = (2.3 ± 0.3) μ b. The effect is seen only in the positive charge state, in agreement with an interpretation as Λ c + . However, it is pointed out that in the same experiment, the non-charmed hyperon state Σ(1385) + also has a cross section much larger than its corresponding negative charge state Σ(1385) − .

Λ0 polarization in proton-proton interactions at √s = 53 and 62 GeV

Abstract Λ 0 s produced in the inclusive reaction pp → Λ° + X with √s = 53 and 62 GeV at the CERN Intersecting Storage Rings are observed to be polarized along the normal to the production plane. In the ranges of longitudinal and transverse momenta, 15–24 and 0.6-1.4 GeV/ c , respectively, the mean polarization is found to be −(0.357±0.055).

Multiwire proportional chamber spectrometer for the CERN intersecting storage rings

Abstract The design, construction, and performance of a multiware proportional chamber (MWPC) system (∼10 k wires) constructed for use at the CERN Intersecting Storage Rings (ISR) is described. This system employs hybrid integrated circuity for pulse detection and storage, and is read out via a CAMAC compatible system. The chambers plus two large-aperture magnets with accompanying scintillation and Cherenkov counters form a versatile multiparticle spectrometer system which has been used to investigate particle systems produced near 0° at the CERN ISR.

pp interactions at 303GeVc: Separation of diffractive and nondiffractive components of the multiplicity distribution

Abstract We have studied the properties of the inclusive pp → pX reation at 303 GeV c . Protons of momentum 1.4 GeV c or less are measured and identified by their ionization. We investigate the multiplicity distribution associated with those events having a small four-momentum transfer to the target proton. Under the assumption that this selection enhances or isolates the diffractive component of the interaction, we discuss the properties of the diffractive and nondiffractive components.

pp Interactions at 303 GeV/c: Production angle distribution

Abstract We have measured the projected production angles of all charged particles in more than 1600 pp interactions at 303 GeV/ c . We have obtained semi-inclusive distributions of pseudo-rapidity and dispersion of pseudo-rapidity event-by-event. The mean dispersion is found to be approximately constant for charged multiplicity, n ch , from 6 to 16.

pp Interactions at 303 GeV/c: Inclusive Studies of γ, K°s, Λ°, π± and Proton Production

In an exposure of the 30 inch hydrogen bubble chamber to a 303 GeV/c proton beam, we have measured both V° events and all tracks with momentum less than 1.4 GeV/c. From these measurements the properties and cross sections of the inclusive pp ⇒ γX, K°sX and Λ°X reactions are studied. In addition, single particle invariant cross sections for pions and protons are presented and the scaling behavior of these reactions is discussed.