Collective centroid oscillations as an emittance preservation diagnostic in linear collider linacs
Transverse bunch centroid oscillations, induced at operating beam currents at which transverse wakefields are substantial, and observed at Beam Position Monitors, are sensitive to the actual magnetic focusing, energy gain, and rf phase profiles in a linac, and are insensitive to misalignments and jitter sources. In the pulse stealing set-up implemented at the SLC, they thus allow the frequent monitoring of the stability of the in-place emittance growth inhibiting or mitigating measures--primarily the energy scaled magnetic lattice and the rf phases necessary for BNS damping--independent of the actual emittance growth as driven by misalignments and jitter. The authors have developed a physically based analysis technique to meaningfully reduce the data. Oscillation beta-beating is a primary indicator of beam energy errors; shifts in the invariant amplitude reflect differential internal motion along the longitudinally extended bunch and thus are a sensitive indicator of the real rf phases in the machine; shifts in betatron phase advance contain corroborative information sensitive to both effects.
- Research Organization:
- Stanford Univ., Stanford Linear Accelerator Center, CA (US)
- Sponsoring Organization:
- USDOE Office of Energy Research, Washington, DC (US)
- DOE Contract Number:
- AC03-76SF00515
- OSTI ID:
- 663290
- Report Number(s):
- SLAC-PUB-7640; CONF-970503-; ON: DE98059133; TRN: US200305%%888
- Resource Relation:
- Journal Volume: 2; Conference: 17. IEEE particle accelerator conference, Vancouver, British Columbia (CA), 05/12/1997--05/16/1997; Other Information: Supercedes report DE98059133; PBD: Aug 1997; PBD: 1 Aug 1997
- Country of Publication:
- United States
- Language:
- English
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