IPAC2014 - List of Authors (Flanagan, J.W.)

Paper	Title	Page
TUPRI067	Recent Results for the Dependence of Beam Instabilities caused by Electron Clouds at CesrTA due to Variations in Bunch Spacing and Chromaticity	1721
	M.G. Billing, K.R. Butler, G. Dugan, M.J. Forster, G. Ramirez, N.T. Rider, K.G. Sonnad, H.A. Williams Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA J.W. Flanagan KEK, Ibaraki, Japan R. Holtzapple, K.E. McArdle, M.I. Miller, M.M. Totten CalPoly, San Luis Obispo, California, USA
	Funding: Work supported by DOE Award DE-FC02-08ER41538, NSF Award PHY-0734867, PHY-1068662 and the Lepton Collider R&D, Coop Agreement: NSF Award PHY-1002467 At the Cornell Electron-Positron Storage Ring Test Accelerator (CesrTA) experiments have been studying the interaction of the electron cloud (EC) with 2.1 GeV stored electron and positron beams. These experiments are intended to characterize the dependence of beam–EC interactions on various beam parameters, such as bunch spacing and vertical chromaticity. Most experiments were performed with 30 or 45-bunch trains, at a fixed current of 0.75 mA/bunch. Earlier experiments with positrons had varied the bunch spacing between 4 and 56 ns at three different vertical chromaticity settings. More recent measurements have included electron-bunch trains to contrast the build up of EC between electron and positron beams. The dynamics of the stored beam was quantified using: a gated Beam Position Monitor (BPM) and spectrum analyzer to measure the frequency spectrum of bunches in the trains; an x-ray beam size monitor to record the bunch-by-bunch, turn-by-turn vertical size of each bunch within the trains. We report on recent ob-servations from these experiments and additional studies, using witness bunches trailing 30 or 45-bunch positron trains, which were used for the generation of the ECs.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRI067
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPME196	Low Energy Coded Aperture Performance at the CesrTA x-Ray Beam Size Monitor	3741
	D.P. Peterson, J.P. Alexander, A. Chatterjee, M. P. Ehrlichman, B.K. Heltsley, A. Lyndaker, N.T. Rider, D. L. Rubin, R.D. Seeley, J.P. Shanks Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA J.W. Flanagan KEK, Ibaraki, Japan
	Funding: U.S. National Science Foundation PHY-0734867, PHY-1002467, PHYS-1068662, U.S. Department of Energy DE-FC02-08ER41538, DE-SC0006505 We report on the design and performance of coded aperture optics elements in the CesrTA x-ray beam size monitor (xBSM). Resolution must be sufficient to allow single-turn measurements of vertical beam sizes of order 10um by imaging synchrotron radiation photons onto a one-dimensional photodiode array. Measurements with beam energies above 2.1GeV and current above 0.1mA can be performed with a single-slit (pinhole) optic. At lower energy or current, small beam size measurements are limited by the diffractive width of a pinhole image and counting statistics. A coded aperture is a multi-slit mask that can improve on the resolution of a pinhole in two ways: higher average transparency improves counting statistics; and the slit pattern and masking transparency can be designed to obtain a diffractive image with narrower features. We have previously implemented coded apertures that are uniform redundant arrays (URA). A new coded aperture design is optimized for imaging with 1.8 GeV beam energy (1.9keV average x-ray energy) and with beam sizes below 20um. Resolution measurements were made in December 2013. Performance of the new coded aperture is compared to the pinhole and the URA.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPME196
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Recent Results for the Dependence of Beam Instabilities caused by Electron Clouds at CesrTA due to Variations in Bunch Spacing and Chromaticity

1721

M.G. Billing, K.R. Butler, G. Dugan, M.J. Forster, G. Ramirez, N.T. Rider, K.G. Sonnad, H.A. Williams
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
J.W. Flanagan
KEK, Ibaraki, Japan
R. Holtzapple, K.E. McArdle, M.I. Miller, M.M. Totten
CalPoly, San Luis Obispo, California, USA

Funding: Work supported by DOE Award DE-FC02-08ER41538, NSF Award PHY-0734867, PHY-1068662 and the Lepton Collider R&D, Coop Agreement: NSF Award PHY-1002467
At the Cornell Electron-Positron Storage Ring Test Accelerator (CesrTA) experiments have been studying the interaction of the electron cloud (EC) with 2.1 GeV stored electron and positron beams. These experiments are intended to characterize the dependence of beam–EC interactions on various beam parameters, such as bunch spacing and vertical chromaticity. Most experiments were performed with 30 or 45-bunch trains, at a fixed current of 0.75 mA/bunch. Earlier experiments with positrons had varied the bunch spacing between 4 and 56 ns at three different vertical chromaticity settings. More recent measurements have included electron-bunch trains to contrast the build up of EC between electron and positron beams. The dynamics of the stored beam was quantified using: a gated Beam Position Monitor (BPM) and spectrum analyzer to measure the frequency spectrum of bunches in the trains; an x-ray beam size monitor to record the bunch-by-bunch, turn-by-turn vertical size of each bunch within the trains. We report on recent ob-servations from these experiments and additional studies, using witness bunches trailing 30 or 45-bunch positron trains, which were used for the generation of the ECs.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRI067

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPME196

Low Energy Coded Aperture Performance at the CesrTA x-Ray Beam Size Monitor

3741

D.P. Peterson, J.P. Alexander, A. Chatterjee, M. P. Ehrlichman, B.K. Heltsley, A. Lyndaker, N.T. Rider, D. L. Rubin, R.D. Seeley, J.P. Shanks
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
J.W. Flanagan
KEK, Ibaraki, Japan

Funding: U.S. National Science Foundation PHY-0734867, PHY-1002467, PHYS-1068662, U.S. Department of Energy DE-FC02-08ER41538, DE-SC0006505
We report on the design and performance of coded aperture optics elements in the CesrTA x-ray beam size monitor (xBSM). Resolution must be sufficient to allow single-turn measurements of vertical beam sizes of order 10um by imaging synchrotron radiation photons onto a one-dimensional photodiode array. Measurements with beam energies above 2.1GeV and current above 0.1mA can be performed with a single-slit (pinhole) optic. At lower energy or current, small beam size measurements are limited by the diffractive width of a pinhole image and counting statistics. A coded aperture is a multi-slit mask that can improve on the resolution of a pinhole in two ways: higher average transparency improves counting statistics; and the slit pattern and masking transparency can be designed to obtain a diffractive image with narrower features. We have previously implemented coded apertures that are uniform redundant arrays (URA). A new coded aperture design is optimized for imaging with 1.8 GeV beam energy (1.9keV average x-ray energy) and with beam sizes below 20um. Resolution measurements were made in December 2013. Performance of the new coded aperture is compared to the pinhole and the URA.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPME196

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)