ANL, Argonne, Illinois, USA
Singular value decomposition (SVD) analysis is a powerful tool for identifying different spatial and timing variation patterns in many fields of researches. Recently we applied complex SVD method to space harmonic analysis of a 13-cell defecting cavity that is built and installed in the APS linac injector for beam phase space characterization and emittance exchange experiments. Real and imaginary space harmonics components are extracted from CST simulated data. Fields inside the iris were expressed in analytic forms and produced good agreement. Work is underway to implement the results into elegant simulation model.
ANL, Argonne, Illinois, USA
A fast beam interlock system for the Advanced Photon Source (APS) Particle Accumulator Ring (PAR) based on the detection of Cerenkov light is proposed for high-charge operations associated with the APS Upgrade (APS-U). Light is generated from lost electrons passing through high-purity, fused-silica fiber optic cable. The cable acts as both radiator and light pipe to a Pb-shielded photomultiplier tube. Results from a prototype installation along the PAR south wall have shown excellent sensitivity, linearity, and reproducibility after 10,000 hours of operation to date with little change in the optical transmission of the fiber. High sensitivity allows more accurate measurement of low-level loss than possible with current monitors. The radiator and detector provide a much faster response than the installed gamma or neutron detectors. A faster, more accurate response to electron loss will be important as we run with higher charge and consider operating at increased energy for APS-U. Initial calibration measurements of the prototype system with radiation monitors for various loss scenarios are discussed. Comparison of the scenarios with simulations are presented.
ANL, Argonne, Illinois, USA
A fast photodetector is used to monitor the bunch duration in the Advanced Photon Source (APS) Particle Accumulator Ring (PAR). The Bunch Duration Monitor (BDM) diagnostic provides an accurate measure of the PAR bunch length. PAR BDM data show good agreement with streak camera measurements. The BDM is based on the metal-semiconductor-metal (MSM) photodetector Hamamatsu G4176-03 MSM with specified rise and fall times of 30 ps. The BDM has sufficient frequency response to resolve the PAR bunch near extraction where, under low-charge conditions, minimum rms pulse durations of 200-300 ps are observed. Beam from the PAR is injected into the Booster; for efficient capture, injected rms bunch duration from the PAR must be less than 600 ps. The MSM detector exhibits a ringing response to fast input signals. To overcome this, the BDM output is de-convolved with the impulse response function of the detector-amplifier circuit. Turn-by-turn bunch duration data is presented versus charge and time in the PAR cycle. Charge calibration is used to determine fit parameters for bunch duration measurements in peak-detection mode. Observations relevant to APS Upgrade high-charge studies are presented.
ANL, Argonne, Illinois, USA
BNL, Upton, Long Island, New York, USA
