Alignment of the ATLAS Inner Detector Tracking System

The ATLAS detector at CERN's Large Hadron Collider (LHC) is equipped with a tracking system at its core (the Inner Detector, ID) consisting of silicon and gaseous straw tube detectors. The physics performance of the ID requires a precision alignment; a challenge involving complex algorithms and significant computing power. The alignment algorithms were already validated on: Combined Test Beam data, Cosmic Ray runs and simulated physics events. The alignment chain was tested on a daily basis in exercises that mimicked ATLAS data taking operations. ID commissioning after final installation into the ATLAS detector has yielded thousands of reconstructed cosmic ray tracks, which have been used for an initial alignment of the ID before the LHC start-up. A hardware system using Frequency Scanning Interferometry will be used to monitor structural deformations. Given the programme outlined here, the ATLAS Inner Detector has had a solid preparation for LHC collisions.Comment: ICHEP0

Searches for Extra Dimensions at the Tevatron

Models in which gravity and/or Standard Model gauge bosons propagate in more than three spatial dimensions have implications that can be tested at current colliders. In this paper, we report on the results from searches for extra dimensions at the two Tevatron experiments, CDF and D0, which utilize up to 200 pb^-1 of proton-antiproton collision data from Run II taken at 1.96 TeV CoM energy, between spring 2002 and fall 2003.Comment: 10 Pages. Proceedings, Hadron Collider Physics (HCP 2004), E. Lansing, Michigan, US

Multi-W Events at LHC from a Warped Extra Dimension with Custodial Symmetry

Randall-Sundrum models based on SU(2)_L * SU(2)_R with custodial symmetry are compelling frameworks for building alternative models of electroweak symmetry breaking. A particular feature of these models is the likely presence of light Kaluza-Klein fermions related to the right-handed top quark. These can be as light as a few hundred GeV and still compatible with EW precision constraints. In this article, we study the detectability of four-W final states at the LHC, which arise from the pair-production and tW decay of light Kaluza-Klein bottom quarks as well as light Kaluza-Klein quarks carrying electric charge 5/3.Comment: 17 pages, 26 figure

Beam Halo Monitoring at CDF

Losses from the proton and antiproton beams of the Fermilab Tevatron have been shown to produce a halo which contribute to backgrounds to physics signals in the Collider Detector at Fermilab (CDF). To provide a measure of the beam halo and losses, we have installed arrays of scintillation counters on both sides of the CDF detector. We describe here the physical configuration of these counters, their implementation and performance within the Fermilab Accelerator Control Network (ACNET). We show correlations between these new devices and the accelerator operating conditions. We point out that the use of these monitors is leading to improvement in the accelerator operations and reduced backgrounds in CDF.Comment: 27 pages, 17 figures, submitted to NIM

Commissioning the ATLAS reconstruction software with first LHC beam and cosmic ray data

Looking towards first LHC collisions, the ATLAS detector is being commissioned using all data available: cosmic rays and events produced during a few days of LHC single beam operations. Commissioning of the full software chain is a main goal, not only to ensure that the reconstruction, monitoring and processing chains are ready to deal with LHC physics data, but also to understand the detector performance as a first step in achieving the ultimate physics expectations. The recorded data have allowed us to study the ATLAS detector in terms of efficiencies, detector integrity, alignment and calibrations. They have also allowed us to test and optimise the sub-systems reconstruction as well as some combined algorithms, such as combined tracking tools. The status of the integration of the complete software chain will be presented and illustrated with data analysis results