The LUCID-2 Detector

LUCID (LUminosity Cerenkov Integrating Detector) is the main luminosity monitor of the ATLAS experiment at LHC and in particular the only one capable of providing bunch-by-bunch luminosity information both online and offline for all beam conditions and luminosity ranges. LUCID-2 refers to the detector upgrade designed to cope with running conditions to be met in RUN-2 (2015-2018) at center of mass energy of 13 TeV: more than 50 pp interactions per bunch crossing and 25 ns bunch-spacing. This report summarises all changes with respect to the detector deployed in RUN-1 (2010-2012), including smaller sensors for higher granularity, new readout electronics for early signal digitisation and a completely new calibration concept guaranteeing long-term stability of the detector response. Overall detector performance and preliminary results on luminosity measurements are presented as well.