Forward physics with rapidity gaps at the LHC

A rapidity gap program with great potential can be realised at the Large Hadron Collider, LHC, by adding a few simple forward shower counters (FSCs) along the beam line on both sides of the main central detectors, such as CMS. Measurements of single diffractive cross sections down to the lowest masses can be made with an efficient level-1 trigger. Exceptionally, the detectors also make feasible the study of Central Diffractive Excitation, and in particular the reaction g + g -> g + g, in the color singlet channel, effectively using the LHC as a gluon-gluon collider.