Author: Sereno, N.
Paper Title Page
MOPPP057 Optimization of the Low-emittance Lattice of the APS Booster Synchrotron 690
  • C. Yao, V. Sajaev, N. Sereno, H. Shang
    ANL, Argonne, USA
  Funding: Work supported by U.S. Department of Energy, Offices of Science, Office of Basic Energy Sciences, under contract No. DE-AC02-06- CH11357.
The APS booster is a 7GeV electron synchrotron. Three lattices have been originally designed with a nominal beam emittance of 132, 109, and 92 nm, respectively. In the past we have mostly operated the booster with the 132 nm lattice because of its better stability. The lower-emittance lattices are not utilized. In early 2010 we upgraded the booster ramp correction and reduced the 360Hz current ripples of the ramp supplies. Current ramp errors have been significantly reduced. This raises our interest in running the low- emittance lattice to improve APS storage ring injection efficiency and reduce radiation losses. This report presents the optimization methods and measurement results of booster beam performance of the booster 92nm lattice.
WEPPP071 Phase Noise Studies at the Advanced Photon Source 2873
  • N. Sereno, G. Decker, R.M. Lill, B.X. Yang
    ANL, Argonne, USA
  Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
Phase noise generated primarily by power line harmonics modulating the 352-MHz rf system in the APS storage ring is a dominant source of high- frequency beam motion, both longitudinally and transversely, due to dispersion in the lattice. It also places fundamental limits on the ability to generate picosecond-scale x-ray pulses for fast pump / probe experiments*. Measurements using turn-by-turn beam position monitors (BPMs) located at high-dispersion locations are compared and contrasted with results from a dedicated S-band phase detector connected to either a capacitive pickup electrode or a diamond x-ray detector. Horizontal beam position at high-dispersion locations is related directly to beam phase by a very simple relation involving the momentum compaction. Simulation results are used to validate this relationship and to quantify the relation between phase noise on the main rf vs beam arrival time jitter.
* A. Zholents et al., NIM A 425, 385 (1999).
WEPPP072 Beam Characterization and Coherent Optical Transition Radiation Studies at the Advanced Photon Source Linac 2876
  • J.C. Dooling, R.R. Lindberg, N. Sereno, C.-X. Wang
    ANL, Argonne, USA
  • A.H. Lumpkin
    Fermilab, Batavia, USA
  Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under contract number DE-AC02-06CH11357.
The Advanced Photon Source facility includes a 450-MeV S-band linac with the option for injection from a photocathode (PC) rf gun. A diode-pumped, twice-frequency doubled Nd:glass regen laser (263 nm) is used with the Cu PC to generate the electron beams. Characterization of these beams and studies of the microbunching instability following beam compression in the four-dipole magnetic chicane are described. A suite of diagnostics is employed including a three-screen emittance section, a FIR coherent transition radiation autocorrelator, electron spectrometers, and an optical diagnostics end station. An energy chirp impressed on the beam is used to compress the 1-2 ps, rms bunch as it passes through the chicane. With compression, bunch lengths of 170-200 fs, rms at 450 pC are measured, and coherent optical transition radiation (COTR) due to the microbunching instability is observed. Mitigation techniques of the COTR in the beam profile diagnostics are demonstrated both spectrally and temporally. At 100 pC without compression normalized transverse emittances of 1.8 and 2.7 microns are observed in the x and y planes, in reasonable agreement with initial ASTRA simulations.