ATLAS is one of the four experiments at the LHC pp collider at CERN, Geneva. The experiment, designed to investigate wide range of physics processes, requires precise measurement of accelerator’s luminosity to predict rates of processes with small cross sections (e.g. production of Higgs boson). The ALFA detectors (Absolute Luminosity For ATLAS), located on av. 240 m on both sides from the ATLAS Interaction Point (IP), provide independent luminosity measurement by counting protons elastically scattered at small angles. The measurement can be performed only at low luminosity and special LHC optics (high β*) which allow close approaching the LHC beams by the ALFA detectors. Duration of such settings is limited and requires that the calibration of detectors have to run in parallel with the measurement. Distant location from the ATLAS IP creates challenges with integration and synchronization of ALFA local timing and triggering with the ATLAS Trigger and Data Acquisition System (TDAQ). This paper briefly reviews construction of the ALFA detectors, organization of the front-end electronics and concentrates on hardware integration with the ATLAS trigger system

Date Published: 25 October 2013
PDF: 6 pages
Proc. SPIE 8903, Photonics Applications in Astronomy, Communications, Industry, and High-Energy Physics Experiments 2013, 89032K (25 October 2013); doi: 10.1117/12.2041876

Published in SPIE Proceedings Vol. 8903:
Photonics Applications in Astronomy, Communications, Industry, and High-Energy Physics Experiments 2013
Ryszard S. Romaniuk, Editor(s)