[en] The upgrade of the HERA accelerator has provided much increased collider luminosity. In turn, the improvements have necessitated a new design for the ZEUS luminosity measurements. The intense synchrotron radiation field, as well as the high probability of a bremsstrahlung photon in each bunch crossing, posed new experimental constraints. In this report, we describe how these challenges were met with the ZEUS luminosity spectrometer system. The design, testing and commissioning of the device are described, and the results from the initial operational experience are reported. (orig.)

[en] The gas mixtures generally used until now in limited streamer tube detectors (Ar + C₄H₁₀ or Ar + CO₂ + C₅H₁₂) are very flammable when leaked into air. The safety issues are therefore very relevant for large-volume underground experiments. We have found a set of completely safe (i.e. nonflammable) ternary mixtures of the kind Ar + hydrocarbon + CO₂ containing less than ≅ 5% of Ar and less than ≅ 10% of hydrocarbon. We tested C₄H₁₀, C₅H₁₂ and C₆H₁₄ as quenching agents. The main characteristics of the various mixtures have been measured: singles (untriggered) counting rate versus high voltage and with different dead times, and average charge. The stability of these mixtures is good, and their spurious streamer activity is compared with the standard binary or ternary mixture. We studied in particular the combination Ar(2.5%) + C₄H₁₀(9.5%) + CO₂(88%). All the data suggest that this or a similar gas mixture can successfully replace standard flammable mixtures both in tracking devices and hadron calorimeters. (orig.)

[en] The design of the pad readout electronics of the Warm Iron Calorimeter for the SLD detector at SLAC, consisting of about 9,000 analog channels, is described. Results of various tests performed during the construction, installation and commissioning of the electronics mounted on the detector are presented. (orig.)

[en] The design of the pad readout electronics of the Warm Iron Calorimeter for the SLD detector at SLAC, consisting of about 9000 analog channels, is described. Results of various tests performed during the construction, installation and commissioning of the electronics mounted on the detector are presented. 10 refs., 12 figs

[en] Results are presented of a study of opposite-sign dimuon events observed in a fine-grained neutrino detector exposed to the Fermilab Tevatron wide-band neutrino beam. A total of 300 background-corrected μ⁺μ^- events induced by incident neutrinos and antineutrinos with energies up to 500 GeV were accumulated. The data were analyzed in terms of a model based on charm-quark production followed by semileptonic decay of the charmed meson. The Cabibbo-Kobayashi-Maskawa matrix terms were found to be |U_cd|²=0.0378±0.0127 (stat)_-0.0082^+0.0099 (syst), and κ|U_cs|²=0.391±0.076 (stat)_-0.066^+0.097 (syst). The ratio of the strange to nonstrange sea in the nucleon, κ=2S/(bar U+bar D), was measured to be 0.407±0.075 (stat)_-0.069^+0.103 (syst)

[en] We present the results of a systematic study of three-component gas mixtures containing argon, isobutane, and carbon dioxide. The study used production-type chambers from the SLD Warm Ion Calorimeter (WIC), instrumented with standard plastic streamer tubes, and triggered by cosmic-ray muons. Pulse height spectra are presented as a function of high voltage, over a wide range of mixtures of these three gases. Various features and similarities observed throughout this three-dimensional mixture space are important clues to an understanding of the underlying physics of discharge mechanisms in wire detectors. (orig.)

[en] The upgrade of the HERA accelerator has provided much increased collider luminosity. In turn, the improvements have necessitated a new design for the ZEUS luminosity measurements. The intense synchrotron radiation field, as well as the high probability of a bremsstrahlung photon in each bunch crossing, posed new experimental constraints. In this report, we describe how these challenges were met with the ZEUS luminosity spectrometer system. The design, testing and commissioning of the device are described, and the results from the initial operational experience are reported

[en] The design and construction of the ZEUS forward tracking detector is described. The detector consists of 3 large planar drift chambers mounted in the forward direction with respect to the proton beam and a smaller rear detector of the same type. Test beam measurements performed at DESY show a single wire spatial resolution of 105 μm and a dE/dx resolution of 8.8%. The resolution of the three dimensional track coordinates and slopes provided by one chamber are found to be 90μm and 2.7 mrad, respectively. (orig.)

[en] The entire data acquisition chain, from the custom made front-end electronics to the Fastbus readout and data reduction module, for the digital readout of the SLD limited streamer tube Warm Iron Calorimeter and Muon Identifier is described. Also described is a Fastbus cosmic logic unit being developed to achieve the capability of reading cosmic ray events, also during the intercrossing time, for apparatus monitoring and calibration purposes. (orig.)

[en] The OLYMPUS experiment used a 0.3 T toroidal magnetic spectrometer to measure the momenta of outgoing charged particles. In order to accurately determine particle trajectories, knowledge of the magnetic field was needed throughout the spectrometer volume. For that purpose, the magnetic field was measured at over 36,000 positions using a three-dimensional Hall probe actuated by a system of translation tables. We used these field data to fit a numerical magnetic field model, which could be employed to calculate the magnetic field at any point in the spectrometer volume. Calculations with this model were computationally intensive; for analysis applications where speed was crucial, we pre-computed the magnetic field and its derivatives on an evenly spaced grid so that the field could be interpolated between grid points. We developed a spline-based interpolation scheme suitable for SIMD implementations, with a memory layout chosen to minimize space and optimize the cache behavior to quickly calculate field values. This scheme requires only one-eighth of the memory needed to store necessary coefficients compared with a previous scheme (Lekien and Marsden, 2005 [1]). This method was accurate for the vast majority of the spectrometer volume, though special fits and representations were needed to improve the accuracy close to the magnet coils and along the toroidal axis.