Electron and Photon Identification Performance in ATLAS

The understanding of the reconstruction and calibration of electrons and photons is one of the key steps at the start-up of data-taking with ATLAS at the LHC (Large Hadron Collider). The calorimeter cells are electronically calibrated before being clustered. Corrections to local position and energy measurements are applied to take into account the calorimeter geometry. Finally, longitudinal weights are applied to correct for energy loss upstream of the calorimeter. As a last step the Z -> ee events will be used for in-situ calibration using the Z boson mass. The electron identification is based on the shower shape in the calorimeter and relies heavily on the tracker and combined tracker/calorimeter information to achieve the required rejection of 10^5 against QCD jets for a reasonably clean inclusive electron spectrum above 20-25 GeV. For photon identification, in addition to the shower shape in the calorimeter, recovery of photon conversions is an essential ingredient given the large amount of material in the inner tracker. The electron and photon identification methods (cuts and multivariate analysis) will be discussed.Comment: Poster write-up at ICHEP08, Philadelphia, USA, July 2008. 4 pages, LaTeX, 7 eps figures, 2 rtx files, 1 sty file and 1 cls fil

Mix-and-match compatibility in asymmetric system markets

This paper shows that the private incentive for mix-and-match compatibility in system markets diverges from the social planner's incentive if competing suppliers are asymmetric in production cost or product quality. There can be too much or too little compatibility when the market is served by fully integrated system suppliers. Also, the market outcome involves socially too much incompatibility in the form of exclusive technological alliances when the market is composed of independent component suppliers. These results contrast with the standard one obtained in the symmetric setup and shed new light on public policy towards compatibility, technological alliances, and bundling practices in system markets

Electronic structures of Zn1−x_{1-x}Cox_xO using photoemission and x-ray absorption spectroscopy

Electronic structures of Zn$_{1-x}$Co$_x$O have been investigated using photoemission spectroscopy (PES) and x-ray absorption spectroscopy (XAS). The Co 3d states are found to lie near the top of the O $2p$ valence band, with a peak around $\sim 3$ eV binding energy. The Co $2p$ XAS spectrum provides evidence that the Co ions in Zn$_{1-x}$Co$_{x}$O are in the divalent Co$^{2+}$ ($d^7$) states under the tetrahedral symmetry. Our finding indicates that the properly substituted Co ions for Zn sites will not produce the diluted ferromagnetic semiconductor property.Comment: 3 pages, 2 figure