Forward Detectors in ATLAS: LUCID, ZDC and ALFA

In order to determine the experimental cross sections for the observed physics processes and point out signatures of new physics an estimation of the absolute luminosity is needed. ATLAS will make extensive usage of detectors in the forward region each one with a different task. LUCID, ZDC and ALFA will be able to monitor the bunch-by-bunch luminosity, help the beam tuning and provide a measurement on both the absolute luminosity and the total cross section. The methodologies for luminosity monitoring and total cross section estimation at the LHC will be reviewed in this paper along with the dedicated detectors of the ATLAS experiment.