Professor Amanda Cooper-Sarkar

Abstract:

The proton-dissociative diffractive photoproduction of J/ψ mesons has been studied in ep collisions with the ZEUS detector at HERA using an integrated luminosity of 112 pb-1. The cross section is presented as a function of the photon-proton centre-ofmass energy and of the squared four-momentum transfer at the proton vertex. The results are compared to perturbative QCD calculations.

Abstract:

The production of charm and beauty quarks in ep interactions has been measured with the ZEUS detector at HERA for squared four-momentum exchange Q2>20 GeV2, using an integrated luminosity of 126 pb-1. Charm and beauty quarks were identified through their decays into muons. Differential cross sections were measured for muon transverse momenta pTμ> 1.5 GeV and pseudorapidities -1. 6<ημ>2. 3, as a function of pTμ>, ημ, Q2and Bjorken x. The charm and beauty contributions to the proton structure function F2were also extracted. The results agree with previous measurements based on independent techniques and are well described by QCD predictions. © Springer-Verlag / Società Italiana di Fisica 2009.

Abstract:

More than half a million minimum-bias events of LHC collision data were collected by the ATLAS experiment in December 2009 at centre-of-mass energies of 0.9 TeV and 2.36 TeV. This paper reports on studies of the initial performance of the ATLAS detector from these data. Comparisons between data and Monte Carlo predictions are shown for distributions of several track-and calorimeter-based quantities. The good performance of the ATLAS detector in these first data gives confidence for successful running at higher energies.

Abstract:

Charged particle production has been studied in neutral current deep inelastic ep scattering with the ZEUS detector at HERA using an integrated luminosity of 0.44 fb?1. Distributions of scaled momenta in the Breit frame are presented for particles in the current fragmentation region. The evolution of these spectra with the photon virtuality, Q2, is described in the kinematic region 10 < Q2< 41000Ge V2. Next-to-leading-order and modified leading-log-approximation QCD calculations as well as predictions from Monte Carlo models are compared to the data. The results are also compared to e+e? annihilation data. The dependences of the pseudorapidity distribution of the particles on Q2 and on the energy in the p system, W, are presented and interpreted in the context of the hypothesis of limiting fragmentation.

Abstract:

The simulation software for the ATLAS Experiment at the Large Hadron Collider is being used for large-scale production of events on the LHC Computing Grid. This simulation requires many components, from the generators that simulate particle collisions, through packages simulating the response of the various detectors and triggers. All of these components come together under the ATLAS simulation infrastructure. In this paper, that infrastructure is discussed, including that supporting the detector description, interfacing the event generation, and combining the GEANT4 simulation of the response of the individual detectors. Also described are the tools allowing the software validation, performance testing, and the validation of the simulated output against known physics processes. © 2010 CERN for the benefit of the ATLAS collaboration.