Integration of Detectors into a Large Experiment: Examples from ATLAS and CMS

Abstract

The Large Hadron Collider (LHC) is the proton-proton accelerator which began operation in 2010 in the existing LEP tunnel at CERN in Geneva, Switzerland. It represents the next major step in the high-energy frontier beyond the Fermilab Tevatron (proton-antiproton collisions at a centre-of-mass energy of 2 TeV), with its design centre-of-mass energy of 14 TeV and luminosity of 10 34 cm −2 s −1. The high design luminosity is required because of the small cross-sections expected for many of the benchmark processes (Higgs-boson production and decay, new physics scenarios such as supersymmetry, extra dimensions, etc.) used to optimise the design of the general-purpose detectors over a period of 15 years or so. To achieve this luminosity and minimise the impact of simultaneous inelastic collisions occurring at the same time in the detectors (a phenomenon usually called pileup), the LHC beam crossings are 25 ns apart in time, resulting in 23 inelastic interactions per crossing on average at design luminosity. Two general-purpose experiments, ATLAS and CMS, were proposed for operation at the LHC in 1994 [1], and approved for construction in 1995. The experimental challenges undertaken by these two projects of unprecedented size and complexity in the field of high-energy physics, the construction and integration achievements realised over the years 2000-2008, and the expected performance of the commissioned detectors are described in a variety of detailed documents, such as the detector papers [2, 3]. In this chapter, much of the description of the lessons learned based on this huge effort, and of D. Froidevaux () CERN,