Synchronous phase measurements in the LHC for electron cloud observations

This Note summarizes the e-cloud observations done in the LHC with 50 ns and 25 ns spaced beams during 2012. Bunch-by-bunch synchronous phase measurements were used to study the e-cloud build-up along bunch trains and to calculate the beam power loss due to e-cloud. The 50 ns beams did not present any sign of e-cloud from the beginning of the 2012 run, thanks to the conditioning achieved in the previous year. On the contrary, the e-cloud effect was strong at the beginning for 25 ns beams, but it was reduced after the scrubbing run and finally it was possible to accelerate 25 ns beams to 4 TeV and put them into collisions. Synchronous phase measurements presented in this paper allow to follow all these changes in the e-cloud effect.