The following email has been sent to SFORZA, Federico:

===

Dear Federico Sforza,

The submission of your abstract has been successfully processed.

Abstract submitted: https://indico.cern.ch/userAbstracts.py?confId=192695.

Status of your abstract: https://indico.cern.ch/abstractDisplay.py?abstractId=68&confId=192695.

See below a detailed summary of your submitted abstract:

Conference: Tipp 2014 - Third International Conference on Technology and Instrumentation in Particle Physics

Submitted by: SFORZA, Federico

Submitted on: 29 January 2014 12:25

Title: Upgrade of the ATLAS muon spectrometer with the installation of new precision drift-tube chambers in 2014

Abstract content The shutdown of the Large Hadron Collider (LHC) at CERN in the years 2013 and 2014 offers the opportunity to improve the performance of the ATLAS muon spectrometer by installing additional muon tracking chambers. The additional chambers use a new technology with precision drift-tubes of half the diameter of the standard ATLAS monitored drift-tubes, thus allowing for a more compact geometry. This makes possible the addition of a third layer of precision muon tracking chambers in detector areas that are, at present, instrumented with two layers of chambers. The momentum resolution of 1 TeV muons reconstructed in the upgraded regions will improve from 28% to 19%, a value consistent with the rest of the muon spectrometer. The new chambers are designed for simple integration with the present service system, the read-out electronics and muon reconstruction software. In order to provide access to the inner part of the ATLAS detector, the new chambers will be mounted on a movable structure that can be aligned with the other chambers with 30 $\mu$m accuracy.

Summary The shutdown of the Large Hadron Collider (LHC) at CERN, taking place in 2013-2014, offers the opportunity to improve the performance of the ATLAS detector with the installation of new detector components. However the relatively short time window and the constraints due to the integration of the new components with the existing infrastructure limits the range of available solutions.

We present the upgrade of a section of the ATLAS muon tracker with drift-tube chambers characterized by a new technology, with smaller tube diameter than the present Monitored Drift-Tube (MDT) chambers. The proposed layout balances between maximizing the coverage with muon stations, the tight constraints of the integration with the present infrastructure, and the benefits of using the new stations for detector R & D.

Each new chamber is composed by eight layers of 78 aluminum tubes with a diameter of 15 mm, against to the six layers of 30 mm aluminum tubes used in the corresponding ATLAS MDT chambers. A gold-plated tungsten-rhenium anode wire is tensed at the center of the tubes with a position precision better than 10 $\mu$m. The design remains fully compatible with the present services, read-out and trigger scheme but the more compact geometry of the chambers allows their installation in currently unequipped regions of the detector structure. The presence of additional tube layers increase the redundancy in the track reconstruction and allows for better noise rejection in the dense tracking environments expected for the future LHC run conditions.

Two new chambers will be installed in the ATLAS detector elevator shaft. This region, covering an area of $\Delta \eta \times\Delta\phi\approx 0.2\times 0.3$ and corresponding to 1% of the ATLAS barrel region, is used to access the inner part of the ATLAS detector and the ease of accessibility must be maintained. This additional challenge has been solved by installing the stations on movable supports and using an optical alignment system, designed to be precise at the level of 30 $\mu$m, integrated with the rest of the ATLAS muon spectrometer.

The upgrade will increase the area of the muon spectrometer equipped with three layers of precision tracking chambers. This will improve the momentum resolution of the newly instrumented regions, for 1 TeV muons, from 28% to 19%, consistently with the rest of the ATLAS muon spectrometer. The installed chambers are also the first step of a larger upgrade of the muon spectrometer barrel region planned for the ATLAS Phase II upgrade.

Primary Authors: Dr. SFORZA, Federico, On Behalf Of Atlas Muon Collaboration (Max-Planck-Institut fuer Physik (Werner-Heisenberg-Institut) (D) federico.sforza@cern.ch

Co-authors:

Abstract presenters: Dr. SFORZA, Federico, On Behalf Of Atlas Muon Collaboration

Track classification: Sensors: 1c) Gaseous Detectors Experiments: 2a) Experiments & Upgrades

Presentation type: --not specified--

Comments: The abstract is submitted on behalf of ATLAS Muon Collaboration. The author name has been modified to show this, but please let me know if the change is in the right format.