The Optical Alignment System of the ZEUS MicroVertex Detector

TL;DR

The paper describes the laser-based optical alignment system of the ZEUS microvertex detector, which monitors structural stability with high precision over five years, enhancing detector alignment for particle physics experiments.

Contribution

It introduces a fully integrated laser alignment system using amorphous-silicon sensors, achieving precise monitoring of detector support structure movements over an extended period.

Findings

Achieved alignment stability periods for track-based calibration.

Measured support structure movements with approximately 10 micrometer precision.

Successfully integrated environmental monitoring with alignment data collection.

Abstract

The laser alignment system of the ZEUS microvertex detector is described. The detector was installed in 2001 as part of an upgrade programme in preparation for the second phase of electron-proton physics at the HERA collider. The alignment system monitors the position of the vertex detector support structure with respect to the central tracking detector using semi-transparent amorphous-silicon sensors and diode lasers. The system is fully integrated into the general environmental monitoring of the ZEUS detector and data has been collected over a period of 5 years. The primary aim of defining periods of stability for track-based alignment has been achieved and the system is able to measure movements of the support structure to a precision around $10 \mu$m.