IPAC2016 - List of Authors (Rubin, D. L.)

Paper	Title	Page
TUPOR021	Incoherent Vertical Emittance Growth from Electron Cloud at CesrTA	1707
	S. Poprocki, J.A. Crittenden, S.N. Hearth, J.D. Perrin, D. L. Rubin, S. Wang Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Funding: Work supported by the US National Science Foundation PHY-1416318, PHY-0734867, and PHY-1002467, and the U.S. Department of Energy DE-FC02-08ER41538 We report on measurements of electron cloud (EC) induced tune shifts and emittance growth at the Cornell Electron-Positron Storage Ring Test Accelerator (CesrTA) with comparison to tracking simulation predictions. The simulations are based on a weak-strong model of the interaction of the positron beam (weak) with the electron cloud (strong), using electric fields computed with established EC buildup simulation codes (ECLOUD). Experiments were performed with 2.1 GeV positrons in a 30 bunch train with 14 ns bunch spacing and 9 mm bunch length, plus a witness bunch at varying distance from the train to probe the cloud as it decays. Measurements of the horizontal and vertical coherent tune shifts and horizontal and vertical bunch size were obtained for a range of train and witness bunch currents, and compared to simulations.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOR021
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WEPMW004	Progress in Detector Design and Installation for Measurements of Electron Cloud Trapping in Quadrupole Magnetic Fields at CesrTA	2420
	J.A. Crittenden, S. Barrett, M.G. Billing, K.A. Jones, Y. Li, T.I. O'Connell, K. Olear, S. Poprocki, D. L. Rubin, J.P. Sikora Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Funding: Work supported by the US National Science Foundation PHY-1416318, PHY-0734867, PHY-1002467, and the U.S. Department of Energy DE-FC02-08ER41538 Following up on our 2013 and 2014 measurements of electron cloud trapping in a quadrupole magnet with 7.4~T/m gradient in the 5.3~GeV positron storage ring at Cornell University, we have redesigned the shielded-stripline time-resolving electron detector and installed a wide-aperture quadrupole magnet at a location in the ring where its field can be compensated by a nearby quadrupole, thus allowing the first measurements of cloud trapping as a function of field gradient. The transverse acceptance of the electron detector has been tripled, allowing tests of model predictions indicating a dramatic cloud splitting effect which exhibits a threshold behavior as a function of bunch population. In addition, a vacuum chamber optimized for cloud buildup measurements using resonant microwave phenomena has been employed. We describe design considerations and modeling predictions for the upcoming 2016 data-taking run. This project is part of the CESR Test Accelerator program, which investigates performance limitations in low-emittance storage and damping rings.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMW004
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WEPOW053	CESR Lattice for Two Beam Operations with Narrow Gap Undulators at CHESS	2968
	S. Wang, D. L. Rubin, J.P. Shanks Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Funding: Work was supported by NSF DMR-0936384 and NSF DMR-1332208. CESR has operated as a dedicated light source since the conclusion of colliding beam program in 2008. Two undulators with a 6.5mm-vertical gap were installed in Fall 2014, replacing a wiggler in the sextant of CESR that is the home to all CHESS beam lines. In order to operate narrow gap undulators with two beams, CESR pretzel lattice was redesigned so that e^- and e⁺ orbits are coincident in one machine sextant but separated in return arcs. In particular both e^- and e⁺ orbits are on axis through undulators. This "arc-pretzel" lattice has been the basis for undulator operation. To better understand the beam dynamics and improve machine performance, we developed many simulation tools: undulator modeling, injection tracking, etc. With installation of an additional quadrupole near undulators, the CESR lattice will be further modified with a low beta waist in the insertion devices, allowing a more than two fold reduction of local beta functions. This reduction is anticipated to mitigate the effects of small aperture and undulator field errors and to enhance the xray brightness. The characterization of the lattice will be compared with measurements of injection efficiency, tune scans, etc.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOW053
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Paper

Title

Page

Incoherent Vertical Emittance Growth from Electron Cloud at CesrTA

1707

S. Poprocki, J.A. Crittenden, S.N. Hearth, J.D. Perrin, D. L. Rubin, S. Wang
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: Work supported by the US National Science Foundation PHY-1416318, PHY-0734867, and PHY-1002467, and the U.S. Department of Energy DE-FC02-08ER41538
We report on measurements of electron cloud (EC) induced tune shifts and emittance growth at the Cornell Electron-Positron Storage Ring Test Accelerator (CesrTA) with comparison to tracking simulation predictions. The simulations are based on a weak-strong model of the interaction of the positron beam (weak) with the electron cloud (strong), using electric fields computed with established EC buildup simulation codes (ECLOUD). Experiments were performed with 2.1 GeV positrons in a 30 bunch train with 14 ns bunch spacing and 9 mm bunch length, plus a witness bunch at varying distance from the train to probe the cloud as it decays. Measurements of the horizontal and vertical coherent tune shifts and horizontal and vertical bunch size were obtained for a range of train and witness bunch currents, and compared to simulations.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOR021

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

WEPMW004

Progress in Detector Design and Installation for Measurements of Electron Cloud Trapping in Quadrupole Magnetic Fields at CesrTA

2420

J.A. Crittenden, S. Barrett, M.G. Billing, K.A. Jones, Y. Li, T.I. O'Connell, K. Olear, S. Poprocki, D. L. Rubin, J.P. Sikora
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: Work supported by the US National Science Foundation PHY-1416318, PHY-0734867, PHY-1002467, and the U.S. Department of Energy DE-FC02-08ER41538
Following up on our 2013 and 2014 measurements of electron cloud trapping in a quadrupole magnet with 7.4~T/m gradient in the 5.3~GeV positron storage ring at Cornell University, we have redesigned the shielded-stripline time-resolving electron detector and installed a wide-aperture quadrupole magnet at a location in the ring where its field can be compensated by a nearby quadrupole, thus allowing the first measurements of cloud trapping as a function of field gradient. The transverse acceptance of the electron detector has been tripled, allowing tests of model predictions indicating a dramatic cloud splitting effect which exhibits a threshold behavior as a function of bunch population. In addition, a vacuum chamber optimized for cloud buildup measurements using resonant microwave phenomena has been employed. We describe design considerations and modeling predictions for the upcoming 2016 data-taking run. This project is part of the CESR Test Accelerator program, which investigates performance limitations in low-emittance storage and damping rings.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMW004

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WEPOW053

CESR Lattice for Two Beam Operations with Narrow Gap Undulators at CHESS

2968

S. Wang, D. L. Rubin, J.P. Shanks
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: Work was supported by NSF DMR-0936384 and NSF DMR-1332208.
CESR has operated as a dedicated light source since the conclusion of colliding beam program in 2008. Two undulators with a 6.5mm-vertical gap were installed in Fall 2014, replacing a wiggler in the sextant of CESR that is the home to all CHESS beam lines. In order to operate narrow gap undulators with two beams, CESR pretzel lattice was redesigned so that e^- and e⁺ orbits are coincident in one machine sextant but separated in return arcs. In particular both e^- and e⁺ orbits are on axis through undulators. This "arc-pretzel" lattice has been the basis for undulator operation. To better understand the beam dynamics and improve machine performance, we developed many simulation tools: undulator modeling, injection tracking, etc. With installation of an additional quadrupole near undulators, the CESR lattice will be further modified with a low beta waist in the insertion devices, allowing a more than two fold reduction of local beta functions. This reduction is anticipated to mitigate the effects of small aperture and undulator field errors and to enhance the xray brightness. The characterization of the lattice will be compared with measurements of injection efficiency, tune scans, etc.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOW053

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