Alignment of the Pixel and SCT Modules for the 2004 ATLAS Combined Test Beam

TL;DR

This paper details the alignment procedures of the ATLAS Inner Detector silicon tracker modules during the 2004 Combined Test Beam, demonstrating high-precision alignment across various particle types and energies.

Contribution

It introduces four independent alignment methods validated on real test beam data, achieving micrometer-level precision in module positioning.

Findings

Alignment precision of about 5 micrometers achieved

Consistent results across different alignment methods

Effective validation using known beam particle momenta

Abstract

A small set of final prototypes of the ATLAS Inner Detector silicon tracker (Pixel and SCT) were used to take data during the 2004 Combined Test Beam. Data were collected from runs with beams of different flavour (electrons, pions, muons and photons) with a momentum range of 2 to 180 GeV/c. Four independent methods were used to align the silicon modules. The corrections obtained were validated using the known momenta of the beam particles and were shown to yield consistent results among the different alignment approaches. From the residual distributions, it is concluded that the precision attained in the alignment of the silicon modules is of the order of 5 micrometers in their most precise coordinate.