Beam coupling impedance simulations and measurements for the LHC FP420 detector

Abstract

The FP420 collaboration aims at designing forward proton tagging detectors to be installed in the LHC sectors 420 meters downstream of the ATLAS and CMS detectors. The experiment increases the impedance of the machine, because it requires an indentation of the beam pipe in the form of a pocket to permit the detector close access to the beam. We investigate the geometric and resistive wall impedance with both numerical simulations and a purpose built experiment.