The ATLAS detector as installed in its experimental cavern at point 1 at CERN is described in this paper. A brief overview of the expected performance of the detector when the Large Hadron Collider begins operation is also presented.

The ATLAS Experiment at the CERN Large Hadron Collider

This paper describes the ATLAS experiment as installed in i ts experimental cavern at point 1 at CERN. It also presents a brief overview of the expec ted performance of the detector.

http://absimage.aps.org/image/SES08/MWS_SES08-2008-020010.pdf

Parton distributions with LHC data

A measurement of the Higgs boson mass is presented based on the combined data samples of the ATLAS and CMS experiments at the CERN LHC in the H→γγ and H→ZZ→4l decay channels. The results are obtained from a simultaneous fit to the reconstructed invariant mass peaks in the two channels and for the two experiments. The measured masses from the individual channels and the two experiments are found to be consistent among themselves. The combined measured mass of the Higgs boson is mH=125.09±0.21 (stat)±0.11 (syst)  GeV.

/pdf/combined-measurement-of-the-higgs-boson-mass-in-pp-3ml7f5avlr.pdf

Combined Measurement of the Higgs Boson Mass in pp Collisions at √s=7 and 8 TeV with the ATLAS and CMS Experiments

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.

/pdf/the-atlas-simulation-infrastructure-gw5d3ea9bf.pdf

The ATLAS Simulation Infrastructure

The Muon-to-Electron conversion experiment (Mu2e), under development at Fermilab, seeks to detect direct muon to electron conversion to provide evidence for a process violating muon and electron lepton number conservation that cannot be explained by the Standard Model of particle physics The required magnetic field is produced by a series of superconducting solenoids of various apertures and lengths This paper describes the conceptual design of the 5 T, 4 m long solenoid cold mass with 167 m bore with the emphasis on the magnetic, radiation and thermal analyses

/pdf/conceptual-design-of-the-mu2e-production-solenoid-cold-mass-51e29al7b6.pdf

Conceptual design of the Mu2e production solenoid cold mass

Several high field magnets using Nb/sub 3/Sn superconductor are under development for future particle accelerators. The high levels of stored energy in these magnets can cause high peak temperatures during a quench. The thermo-mechanical stress generated in the winding during the fast temperature rise can result in a permanent damage of the brittle Nb/sub 3/Sn. Although there are several studies of the critical current degradation of Nb/sub 3/Sn strands due to strain, little is known about how to apply the strain limitations to define a maximum acceptable temperature in the coils during a quench. Therefore, an experimental program was launched, aimed at improving the understanding of the effect of thermo-mechanical stress in coils made from brittle Nb/sub 3/Sn. A first experiment, reported here, was performed on cables. The experimental results were compared to analytical and finite element models. The next step in our experimental program will be to repeat similar measurements in small racetrack coils and later in full size magnets.

Effect of thermo-mechanical stress during quench on Nb/sub 3/Sn cable performance

New low-β quadrupole magnets are being developed within the scope of the High Luminosity LHC (HL-LHC) project in collaboration with the US LARP program. The aim of the HLLHC project is to study and implement machine upgrades necessary for increasing the luminosity of the LHC. The new quadrupoles, which are based on the Nb₃Sn superconducting technology, will be installed in the LHC Interaction Regions and will have to generate a gradient of 140 T/m in a coil aperture of 150 mm. In this paper, we describe the design of the short model magnet support structure and discuss results of the detailed 3D numerical analysis performed in preparation for the first short model test.

/pdf/support-structure-design-of-the-hbox-nb-3-hbox-sn-quadrupole-2bohvl3vnn.pdf

Support Structure Design of the $\hbox{Nb}_{3}\hbox{Sn}$ Quadrupole for the High Luminosity LHC

During the last year, Fermilab in collaboration with LBNL and KEK was conducting an extensive design study of a superconducting magnet with a two-layer cosine-theta coil for a post-LHC hadron collider. For the 30-50 mm magnet bore range, two superconducting cable types and various current block arrangements and iron yoke outer diameters were considered. This paper summarizes results of the study including field and force distributions, systematic and random field errors, coil magnetization and iron saturation effects.

Conceptual design study of high field magnets for very large hadron collider

As part of the High Field Magnet program at Fermilab several NbTi and Nb3Sn strands were tested with particular emphasis on the study of voltage spikes and their relationship to superconductor instabilities. The voltage spikes were detected under various experimental conditions using voltage-current (V-I) and voltage-field (V-H) methods. Two types of spikes, designated 'magnetization' and 'transport current' spikes, have been identified. Their origin is most likely related to magnetization flux jump and transport current redistribution, respectively. Many of the signals observed appear to be a combination of these two types of spikes; the combination of these two instability mechanisms should play a dominant role in determining the minimum quench current

Giorgio Ambrosio

Papers

Conceptual design of the Mu2e production solenoid cold mass

Effect of thermo-mechanical stress during quench on Nb/sub 3/Sn cable performance

Support Structure Design of the $\hbox{Nb}_{3}\hbox{Sn}$ Quadrupole for the High Luminosity LHC

Conceptual design study of high field magnets for very large hadron collider

Voltage Spikes in $hboxNb_3hboxSn$ and NbTi Strands