Performance of the LHCb Vertex Detector Alignment Algorithm determined with Beam Test Data

TL;DR

This paper evaluates the performance of the LHCb vertex detector alignment algorithm using beam test data, demonstrating high precision and stability in sensor alignment and hit accuracy.

Contribution

It presents the first detailed assessment of the VELO alignment algorithm's accuracy and stability using beam test data, highlighting improvements in alignment precision.

Findings

Alignment accuracy of ~2 microns and 0.1 mrad achieved

Single hit precision of about 10 microns

System stability maintained under environmental changes

Abstract

LHCb is the dedicated heavy flavour experiment at the Large Hadron Collider at CERN. The partially assembled silicon vertex locator (VELO) of the LHCb experiment has been tested in a beam test. The data from this beam test have been used to determine the performance of the VELO alignment algorithm. The relative alignment of the two silicon sensors in a module and the relative alignment of the modules has been extracted. This alignment is shown to be accurate at a level of approximately 2 micron and 0.1 mrad for translations and rotations, respectively in the plane of the sensors. A single hit precision at normal track incidence of about 10 micron is obtained for the sensors. The alignment of the system is shown to be stable at better than the 10 micron level under air to vacuum pressure changes and mechanical movements of the assembled system.