Proof-of-Principle of a Cherenkov-Tag Detector Prototype

In a recent paper, the authors discussed the feasibility study of an innovative technique based on the directionality of Cherenkov light produced in a transparent material to improve the signal to noise ratio in muon imaging applications. In particular, the method was proposed to help in the correct identification of incoming muons direction. After the first study by means of Monte Carlo simulations with Geant4, the first reduced scale prototype of such a detector was built and tested at the Department of Physics and Astronomy "E. Majorana" of the University of Catania (Italy). The characterization technique is based on muon tracking by means of the prototype in coincidence with two scintillating tiles. The results of this preliminary test confirm the validity of the technique and stressed the importance to enhance the Cherenkov photons production to get a signal well distinguishable with respect to sensors and electronic noise.

New Fitting Concept in ATLAS muon tracking for the LHC Run-2

Muons with high momentum - above 500 GeV - are an important constituent of new physics signatures in many models. Run-2 of the LHC is greatly increasing ATLAS’s sensitivity to such signatures thanks to an ever-larger dataset of such particles, enhanced further by an increase in the center-of-mass energy. The ATLAS Muon Spectrometer chamber alignment contributes significantly to the uncertainty of the reconstruction of these high-momentum objects. The proper treatment of measurements during tracking and the correct propagation of the alignment effects is extremely challenging. Recently, an innovative approach that imposes Gaussian constraints on ensembles of detector hits was implemented. It provides a significant improvement to high-momentum tracking without increasing the CPU budget. Furthermore, it allows for the verification of the expected alignment quality using high-statistics collision data. A detailed discussion of the algorithmic realization is given, the expected performance gains are presented and prospects for further applications of the approach are outlined.

Construction and Test of Full-Size Micromegas Modules for the ATLAS New Small Wheel Upgrade

In 2015 the first full size resistive-strip Micromegas modules for the ATLAS New Small Wheel upgrade will be realized. The goal is to provide precision muon tracking with spatial resolution below 100 μm on trapezoidal four-layer detector modules with areas between 2 and 3 m2. This poses stringent limits on the overall accuracy of the modules with respect to strip positioning and planarity. Each module is built as a quadruplet of four resistive strip Micromegas layers, constructed from stiff sandwich panels. An assembly procedure has been developed to build the panels and modules with the required mechanical precision of 30 μm along the precision coordinate and 80 μm perpendicular to the chamber. The construction and quality assurance procedures ensure good module quality verified by checks done during the construction and the chamber assembly.