W. Struczinski

Cross sections and charged multiplicity distributions for π+p,K+p andpp interactions at 250 GeV/c

Cross sections and charged multiplicity distributions for π+p,K+p andpp interactions at 250 GeV/c are presented and compared to each other as well as to earlier (for π+p andK+p lower energy) data. Consistently, the meson-proton (M+p) data have narrower multiplicity distributions and higher average multiplicity thanpp data. Up to our energy, generalized KNO functions describe the energy dependence of the shape of the multiplity distribution with one parameter forM+p and one forpp collisions. If interpreted in terms of negative binomials, the parameter 1/k tends to be slightly lower forM+p than forpp data. For both types of hadron-hadron collision, 1/k is larger than fore+e− andlp collisions.

Modelling and measurement of charge transfer in multiple GEM structures

Measurements and numerical simulations on the charge transfer in Gas Electron Multiplier (GEM) foils are presented and their implications for the usage of GEM foils in Time Projection Chambers are discussed. A small test chamber has been constructed and operated with up to three GEM foils. The charge transfer parameters derived from the electrical currents monitored during the irradiation with an Fe-55 source are compared with numerical simulations. The performance in magnetic fields up to 2 T is also investigated.Measurements and numerical simulations on the charge transfer in Gas Electron Multiplier (GEM) foils are presented and their implications for the usage of GEM foils in Time Projection Chambers are discussed. A small test chamber has been constructed and operated with up to three GEM foils. The charge transfer parameters derived from the electrical currents monitored duringthe irradiation with an 55 Fe source are compared with numerical simulations. The performance in magnetic fields up to 2 T is also investigated. r 2002 Elsevier Science B.V. All rights reserved. PACS: 29.40.Cs; 29.40.Gx

Multiplicity of charged particles in 800 GeV p-p interactions

Abstract Results are reported concerning the charged-particle multiplicity distribution obtained in an exposure of the high-resolution hydrogen bubble chamber LEBC to a beam of 800 GeV protons at the Fermilab MPS. This is the first time that such data have been available at this energy. The distribution of the number n ch of charged particles produced in inelastic interactions obeys KNO-scaling. The average multiplicity is 〈 n ch 〉 = 10.26±0.15. For n ch ⩾8 the data can be well fitted to a negative binomial. The difference between the overall experimental multiplicity distribution and that resulting from the latter fit is in agreement with the contribution expected from diffractive processes.

Inclusive Charm Cross-Sections in 800-GeV/c p p Interactions

Abstract We report a measurement of the inclusive D/D production cross section in 800 GeV/ c proton-proton interactions. The experiment used the high resolution bubble chamber LEBC exposed to an 800 GeV/ c proton beam at the Fermilab MPS. We obtain σ( D/ D )=59 −15 +22 μ b (statistical errors), having analysed 25% of the total data sample. Comparison with 400 GeV/ c pp dat a obtained with LEBC at CERN shows a D/D cross section increase by a factor of 1.7 −0.5 +0.7 . This is in good agreement with fusion model calculations.

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%.

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.

Testing of FE Hybrids and Si detector modules for the CMS Tracker

Abstract The innermost region of the CMS detector will consist of silicon pixel and silicon microstrip detectors. One microstrip detector module is essentially composed of three elements: a set of silicon sensors, a mechanical support structure and the Front End Electronics (FE hybrid). During the production phase of the CMS tracking device, various quality and functionality tests of each detector component have to be performed to assure a stable tracker performance for a time scale of about 10 years of LHC running. This demands a chain of testing procedures beginning at the Hybrid component level and ending at the assembled module level. Each production and assembly step needs a specific testing environment and procedure (e.g. long- or short-term tests and temperature cyclings). A compact, cost efficient test and diagnostic tool which is suited for the operation and characterization of hybrids and silicon detector modules will be presented. The test setup is mainly composed of two printed circuit boards, one interface to the PC and the graphical user interface.