A new design of a detector plane of sub-millimetre thickness for an electromagnetic sampling calorimeter is presented. It is intended to be used in the luminometers LumiCal and BeamCal in future ...linear e
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collider experiments. The detector planes were produced utilising novel connectivity scheme technologies. They were installed in a compact prototype of the calorimeter and tested at DESY with an electron beam of energy 1–5 GeV. The performance of a prototype of a compact LumiCal comprising eight detector planes was studied. The effective Molière radius at 5 GeV was determined to be (8.1 ± 0.1 (stat) ± 0.3 (syst)) mm, a value well reproduced by the Monte Carlo (MC) simulation (8.4 ± 0.1) mm. The dependence of the effective Molière radius on the electron energy in the range 1–5 GeV was also studied. Good agreement was obtained between data and MC simulation.
High-precision HERA data corresponding to a luminosity of around 1 fb−1 have been used in the framework of eeqq contact interactions (CI) to set limits on possible high-energy contributions beyond ...the Standard Model to electron-quark scattering. Measurements of the inclusive deep inelastic cross sections in neutral and charged current ep scattering were considered. The analysis of the ep data has been based on simultaneous fits of parton distribution functions including contributions of CI couplings to ep scattering. Several general CI models and scenarios with heavy leptoquarks were considered. Improvements in the description of the inclusive HERA data were obtained for a few models. Since a statistically significant deviation from the Standard Model cannot be established, limits in the TeV range were set on all models considered.
A prototype of a luminometer, designed for a future
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collider detector, and consisting at present of a four-plane module, was tested in the CERN PS accelerator T9 beam. The objective of this ...beam test was to demonstrate a multi-plane tungsten/silicon operation, to study the development of the electromagnetic shower and to compare it with MC simulations. The Molière radius has been determined to be 24.0 ± 0.6 (stat.) ± 1.5 (syst.) mm using a parametrization of the shower shape. Very good agreement was found between data and a detailed Geant4 simulation.
The photoproduction of isolated photons has been measured in diffractive events recorded by the ZEUS detector at HERA. Cross sections are evaluated in the photon transverse-energy and pseudorapidity ...ranges 5<ETγ<15 GeV and −0.7<ηγ<0.9, inclusively, and also with a jet with transverse energy and pseudorapidity in the ranges 4<ETjet<35 GeV and −1.5<ηjet<1.8, using a total integrated electron-proton luminosity of 456 pb−1. A number of kinematic variables were studied and compared to predictions from the rapgap Monte Carlo model. An excess of data is observed above the rapgap predictions for zPmeas>0.9, where zPmeas is the fraction of the longitudinal momentum of the colorless “Pomeron” exchange that is transferred to the photon-jet final state, giving evidence for direct Pomeron interactions.
Production of exclusive dijets in diffractive deep inelastic Formula omitted scattering has been measured with the ZEUS detector at HERA using an integrated luminosity of 372 pb Formula omitted. The ...measurement was performed for Formula omitted-p centre-of-mass energies in the range Formula omitted and for photon virtualities Formula omitted. Energy flows around the jet axis are presented. The cross section is presented as a function of Formula omitted and Formula omitted, where Formula omitted, x is the Bjorken variable and Formula omitted is the proton fractional longitudinal momentum loss. The angle Formula omitted is defined by the Formula omitted-dijet plane and the Formula omitted- Formula omitted plane in the rest frame of the diffractive final state. The Formula omitted cross section is measured in bins of Formula omitted. The results are compared to predictions from models based on different assumptions about the nature of the diffractive exchange.
An NLO photon parton parametrization is presented based on the existing measurements from e + e- data and the low-x proton structure function from ep interactions. Also included in the extraction of ...the NLO parton distribution functions are the dijets data coming from γp → j1 + j2 + X. The new parametrization is compared to other NLO parametrizations.
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