Project to install Roman Pot detectors in ATLAS at LHC

The instrumentation consists of two sets of Roman Pots installed respectively at 216 and 224m 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 level2 the position of the IP within onemillimeter precision. This paper presents the feasibility study, the on-going R&D and the issues of such challenging experiment.