Print Publication Year: 2008
Online Publication Date:October 2009
Chapter DOI: http://dx.doi.org/10.1017/CBO9780511534966.016
Subjects: Particle Physics and Nuclear Physics
Our job in physics is to see things simply, to understand a great many complicated phenomena, in terms of a few simple principles.Steven Weinberg
A present-day experiment in high energy physics usually requires a multipurpose experimental setup consisting of at least several (or many) subsystems. This setup (called commonly ‘detector’) contains a multitude of sensitive channels which are necessary to measure the characteristics of particles produced in collisions or decays of the initial particles. A typical set of detector properties includes abilities of tracking, i.e. measurement of vertex coordinates and charged-particle angles, measurements of charged-particle momenta, particle energy determination and particle identification. A very important system is the trigger which detects the occurrence of an event of interest and produces a signal to start the readout of the information from the relevant channels. Since high energy physics experiments are running for months or years, the important task is to monitor and control the parameters of the detector and to keep them as stable as possible. To fulfil this task the detector is usually equipped with a so-called slow control system, which continuously records hundreds of experimental parameters and warns experimentalists if some of them are beyond certain boundaries.
To control the process of accumulating statistics and calculating the cross sections and decay rates, a luminosity measurement system is mandatory (for the term definition, see Chap. 4).