Longitudinal Motion of Uncaptured Particles in the LHC at 7 TeV

The longitudinal motion of uncaptured particles in the presence of synchrotron radiation is analysed in detail for the case with RF on. The time scales and the distribution of the uncaptured particles in the abort gap in the LHC at 7 TeV are calculated for a proton beam. Comparison of the calculated density of lost particles in the abort gap with the tolerable value, defined by the quench limit, gives the limitation on the allowed particle loss rate (or minimum beam lifetime). If this limit is exceeded one may need active cleaning, which can be done using the LHC transverse damper.