Speaker
Jim Crittenden
(Cornell University)
Description
The Cornell Electron Storage Ring Test Accelerator (CesrTA) 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 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 model parameters
such as the photoelectron azimuthal and energy distributions at production,
and the secondary yield parameters including
the true secondary, rediffused, and elastic yield values. In particular,
witness bunch studies exhibit high sensitivity to the elastic yield
by providing information on cloud decay times.
Primary author
Jim Crittenden
(Cornell University)
Co-authors
Giovanni Rumolo
(CERN)
John Sikora
(Cornell University)
Mark Palmer
(Cornell University)
Sergio Calatroni
(CERN)
Xianghong Liu
(Cornell University)
Yulin Li
(Cornell University)
