• J.P. Alexander, C.J. Conolly, E. Fontes, W.H. Hopkins, B. Kreis, H. Liu, A. Lyndaker, M.A. Palmer, D.P. Peterson, P. Revesz, J.J. Savino, R.D. Seeley
  CLASSE, Ithaca, New York
• J.W. Flanagan
  KEK, Ibaraki

Funding: NSF

We report on the performance goals and design of the CESRTA x-ray beam size monitor (xBSM). The xBSM resolution must be sufficient to measure vertical beam sizes under 20um. The xBSM images 2–4keV synchrotron radiation photons onto one-dimensional photodiode array. Instrumentation in the dedicated x-ray beam line includes upstream interchangeable optics elements (slits, coded apertures, and Fresnel zone plates), a monochrometer and the InGaAs photodiode detector. To provide sufficient x-ray flux in 2 GeV operation, the beam line is evacuated, with only a thin diamond window isolating the detector vacuum from the damping ring. The readout is a beam-synchronized FADC that is sufficient to measure consecutive bunches independently in a 4ns bunch spacing configuration.

• J.P. Alexander, W.H. Hopkins, B. Kreis, H. Liu, D.P. Peterson
  CLASSE, Ithaca, New York
• J.W. Flanagan
  KEK, Ibaraki

Funding: NSF

Engineering data sets were collected with the CESRTA x-ray beam size monitor (xBSM) during November 2008 and January 2009 runs. We report on the performance of the InGaAs photodiode array detector, including time response and signal-to-noise. We report on the observed measurement resolution for changes in the damping ring vertical beam size using the interchangeable optics elements: slits, coded apertures, and a Fresnel zone plates. Observed resolutions are compared to predictions based on characteristics of the optics elements.