Project to install Roman Pot detectors in ATLAS at LHC

The instrumentation consists of two sets of Roman Pots installed respectively at 216 and 224 m on both sides from the ATLAS Interaction Point to measure with precision the position (<10 micrometers) and the timing (< 5 picoseconds) of the two diffracted protons intact after interaction. Each roman pot is equipped with several plans of edgeless silicon 3D pixels detector, some planes will have a fast OR outputs defining a PRETRIGGER track segment. These inputs are to be combined in time with the ATLAS Level 1 trigger ACCEPT signal. In addition, the Time Of Flight of each outgoing proton is measured using ultra fast timing detector (MCP-PMT) allowing to constraint further at level 2 the position of the IP within one- millimeter precision. This paper presents the feasibility study, the on-going R&D and the issues of such challenging experiment.