A comparison of electron cloud density measurements

Several techniques have been employed to measure the electron cloud (EC) density in accelerators. These include Time-Resolved Retarding Field Analyzers and Shielded Pickups that sample the flux of cloud electrons onto the beam-pipe wall, as well as TE wave resonance techniques that measure the EC density in a region within the volume of the beam-pipe. We have made measurements to test the EC mitigation properties of different surface coatings and geometries, often with more than one technique used in the same test chamber. We present a comparison of measurements in bare aluminum chambers with those having a TiN coating, as well as the effect of beam conditioning. In addition, we will compare the results of the different measurement techniques used in the same chamber under the same conditions. These measurements were made at the Cornell Electron Storage Ring (CESR) which has been reconfigured as a test accelerator (CESRTA) having positron or electron beam energies ranging from 2 GeV to 5 GeV.