H. Grässler

Maximum particle densities in rapidity space of π+ p, K+ p and pp collisions at 250 GeV/c

Abstract In a study of π + p, K + p and pp collisions at √ s =22GeV in the european hybrid spectrometer (EHS), the maximum charged particle density per given rapidity interval is found to rise linearly with charged particle multiplicity, independent of beam particle type and practically independent of energy between 22 and 900 GeV. An anomalous π + p event is found with ten particles within the very narrow rapidity interval Δy =0.098.

π+p and K+p elastic scattering at 250 GeV/c

Abstract Results are presented on π + p and K + p elastic scattering at 250 GeV/ c , the highest momentum so far reached for positive meson beams. The experiment (NA22) was performed with the european hybrid spectrometer. The π + p elastic cross section stays constant with energy while the K + p cross section increases.

Simultaneous track reconstruction and electron identification in the H1 radial drift chambers

Abstract Results of prototype tests of the radial-wire drift chambers of the H1 forward track detector are presented. Choice of a suitable gas mixture and careful design of the chambers to include the possibility of efficient X-ray detection have shown that tracks can be reconstructed with good accuracy (σ ≈ 110–150 μm) and that simultaneously electron identification can be achieved by pulse integral analysis of ionization energy deposition due to both dE/dx and transition radiation. For 90% electron acceptance the pion contamination is 8% at high momentum (≈ 60 GeV/c). At lower momenta, electron identification is further enhanced by the multiple sampling of pulse integrals in such chambers, resulting at 5 GeV/c in a pion contamination of ≈ 0.5%.

Strangeness suppression and inclusive ¶ and K*0 production in K+p interactions at 250 GeV/c

We present inclusive ¶ and K*0(892) cross sections and Feynman x-spectra in K+ p collisions at 250 GeV/c. In the K+ fragmentation region, x > 0.2, the ratio of ¶ to K*0(892) is used to estimate the strangeness suppression factor λ, with the result γ=0.17 ± 0.02 (stat ± 0.01 (syst). We see no evidence for an energy dependence of λ in the CM energy range 7.8 ≤ s≤21.7 GeV.

Precision reconstruction of charged tracks with simultaneous electron identification in a gaseous detector using transition radiation

Abstract Results are presented from tests of a radial wire drift chamber, the design of which is optimised for both accurate spatial reconstruction of charged tracks and efficient detection of incident X-rays. With flash digitised readout, we demonstrate that analysis of pulse profile can yield good spatial accuracy (σ drift ∼150μm, σ chdiv ∼1% wire length) together with useful hadron/electron discrimination if(π/e∼8% at 60 GeV> c ) using a transition radiator immediately preceding the chamber. The exploitation of this technique at high energy proton-proton and electron-proton collider storage rings is briefly discussed.

e+- identification using the drift chambers and transition radiators of the H1 forward track detector

The status of the operation and performance of the H1 Forward Track Detector at the HERA ep storage rings for the detection of electrons (e−) and positrons (e+) is reported. Events with charged particles produced at small angles (7° 3 GeV. Transition radiation X-rays, produced in polypropylene foil radiators immediately upstream of each radial wire drift chamber, are detected in the latter as ionisation charge additional to the usual dEdx contribution. Progress towards achieving the design eπ discrimination of better than 10% π contamination for 90% e± acceptance, which has been established with single tracks, in the complex multi-track environment of ep events at HERA, is reported.

Electron identification in the H1 radial wire drift chambers

Abstract Tests of a radial wire drift chamber for the H1 experiment at the HERA ep-collider were performed at a test beam at the CERN SPS. These types of chambers, part of the H1 forward track detector, are designed to determine accurate vector track segments and to identify electrons by means of d E d x and transition radiation (TR) detection. The electron/pion discrimination has been evaluated at particle momenta from 5 to 50 GeV/c using gas mixtures containing 15 to 30% xenon. Methods and results of this analysis are presented.

Spatial precision of H1 radial wire drift chambers using gas mixtures suitable for transition radiation detection

Abstract Results are presented from calibration and tests of a radial wire drift chamber for the H1 experiment at the HERA ep collider. The chambers form part of the H1 forward track detector (FTD) and are designed both to determine accurate vector track segments and to identify simultaneously electrons by means of d E d x measurement and transition radiation (TR) detection. The spatial reconstruction accuracy (from drift timing and charge division) has been investigated using gas mixtures suitable for TR X-ray detection. A novel technique for enhancing the precision of determination of the radial (non-drift) coordinate of each track using the drift cell geometry is evaluated. A brief summary of the performance of the three radial wire chambers in the FTD is given.

Charge and energy flow in π+ p,K + p andpp interactions at 250 GeV/c

We present data on the flow of energy and charge in π+p,K+p andpp interactions at 250 GeV/c. The energy and charge flow in the beam c.m. hemisphere is analysed in terms of the cluster-invariant Bialas-Ochs-Stodolsky variable λ=cot θ/Ejet. The profile functionsdQ/dλ anddE/dλ indicate a widening inpT of jets between 32 and 250 GeV/c incident laboratory momentum, whereas the ratiodQ/dE is energy independent. The data are compared to μp deep-inelastic scattering resutls and to expectations from the single string LUND model, the Dual Parton Model and the two-string LUND model (FRITIOF).

A comparison of inclusive ϱ0, ϱ+ and ω production in K+p interactions at 250 GeV/c

Abstract Inclusive data are presented on ϱ 0 ,ϱ + and ω produced in k + p interactions at 250 GeV/ c , for ϱ + and ω for the first time in K + p experiment. In the forward CM hemisphere, the ϱ + , ϱ 0 and ω differential production rates are equal within errors, and remarkably similar to muon-inelastic scattering data on ϱ 0 and ω at 280 GeV/ c .