Performance of the ALICE VZERO system

TL;DR

The paper reviews the design, implementation, and four-year operational performance of the ALICE VZERO system, a key detector component used for triggering, beam monitoring, and physics measurements at the LHC.

Contribution

It provides a comprehensive description of the VZERO system and evaluates its performance in various physics and operational contexts over four years.

Findings

VZERO effectively triggers and monitors beam conditions.

The system accurately measures luminosity and multiplicity.

Operational stability maintained over four years.

Abstract

ALICE is an LHC experiment devoted to the study of strongly interacting matter in proton-proton, proton--nucleus and nucleus-nucleus collisions at ultra-relativistic energies. The ALICE VZERO system, made of two scintillator arrays at asymmetric positions, one on each side of the interaction point, plays a central role in ALICE. In addition to its core function as a trigger, the VZERO system is used to monitor LHC beam conditions, to reject beam-induced backgrounds and to measure basic physics quantities such as luminosity, particle multiplicity, centrality and event plane direction in nucleus-nucleus collisions. After describing the VZERO system, this publication presents its performance over more than four years of operation at the LHC.