  The Cornell Electron Storage Ring Test Accelerator experimental program
includes investigations into electron cloud buildup, applying various
mitigation techniques in custom vacuum chambers. Among these are two 1.1-m-long
sections located symmetrically in the east and west arc regions. These chambers
are equipped with pickup detectors shielded against the direct beam-induced
signal. They detect cloud electrons migrating through an 18-mm-diameter pattern
of small holes in the top of the chamber. A digitizing oscilloscope is used to
record the signals, providing time-resolved information on cloud development.
Carbon-coated, TiN-coated and uncoated aluminum chambers have been tested.
Electron and positron beams of 2.1, 4.0 and 5.3 GeV with a variety of bunch
populations and spacings in steps of 4 and 14 ns have been used. Here we report
on results from the ECLOUD modeling code which highlight the sensitivity of
these measurements to the physical phenomena determining cloud buildup such as
the photoelectron production azimuthal and energy distributions, and the
secondary yield parameters including the true secondary, re-diffused, and
elastic yield values.
