IPAC2017 - List of Authors (Rubin, D. L.)

Paper	Title	Page
TUPVA136	Using Sloppy Models for Constrained Emittance Minimization at the Cornell Electron Storage Ring (CESR)	2418
	W.F. Bergan, A.C. Bartnik, I.V. Bazarov, H. He, D. L. Rubin Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA J.P. Sethna Cornell University, Ithaca, New York, USA
	Funding: DOE DE-SC0013571 NSF DGE-1144153 In order to minimize the emittance at the Cornell Electron Storage Ring (CESR), we measure and correct the orbit, dispersion, and transverse coupling of the beam.* However, this method is limited by finite measurement resolution of the dispersion, and so a new procedure must be used to further reduce the emittance due to dispersion. In order to achieve this, we use a method based upon the theory of sloppy models.** We use a model of the accelerator to create the Hessian matrix which encodes the effects of various corrector magnets on the vertical emittance. A singular value decomposition of this matrix yields the magnet combinations which have the greatest effect on the emittance. We can then adjust these magnet ‘‘knobs'' sequentially in order to decrease the dispersion and the emittance. We present here comparisons of the effectiveness of this procedure in both experiment and simulation using a variety of CESR lattices. We also discuss techniques to minimize changes to parameters we have already corrected. * J. Shanks, D.L. Rubin, and D. Sagan, Phys. Rev. ST Accel. Beams 17, 044003 (2014). ** K.S. Brown and J.P. Sethna, Phys. Rev. E 68, 021904 (2003).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA136
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WEPIK109	Experimental Study of Vertical-Longitudinal Coupling Induced by Wakefields at CesrTA	3200
	S. Wang, J.D. Perrin, S. Poprocki, D. L. Rubin Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Funding: Work supported by NSF PHY-1416318, PHYS-1068662 Transverse vertical wakefields can cause vertical beam size growth in accelerators. Here we report recent measurements and simulations of wakefields from movable scrapers at the CesrTA. The charge dependent vertical beam size growth was observed while a single scraper was inserted through the top of the chamber. No change in the beam size was observed with top and bottom scrapers inserted symmetrically. The apparent growth in the vertical beam size was due in large part to the y-z coupling (vertical crabbing) induced by the monopole wake of the asymmetric scraper configuration. We explored this y-z coupling by varying vertical betatron phase advance between the vertical beam size monitor and the scrapers. In addition, we found that existing residual, current independent y-z coupling could be compensated by the scraper wake. Predictions of a tracking simulation are in good agreement with the measurements.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK109
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WEPIK110	Resistive Wall Instability and Impedance Studies of Narrow Undulator Chamber in CHESS-U	3204
	S. Wang, M.G. Billing, S. Poprocki, D. L. Rubin, D. Sagan Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Funding: Work supported by NSF DMR-0936384 and NSF DMR-1332208 In a major upgrade of the Cornell Electron Storage Ring (CESR) one sextant of ring will be replaced with double bend achromats (DBAs) and undulator straights for x-ray users. The resistive wall impedance from the narrow gap (4.5 mm) undulator chambers (5 m per straight) may limit total beam. Here we report recent results of modelling and calculation of multibunch instabilities due to the impedance of chamber walls and transition tapers. The short range wakefields and resistive wall impedance are modelled and incorporated in a tracking simulation. The coupled-bunch growth rate found with the tracking study is in good agreement with the analytic approximation. We find that the resistive wall instability can be readily damped by our existing bunch-by-bunch feedback system.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK110
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THPVA073	Latest Results on Fast Kicker for g-2 E-989 Experiment at Fermilab	4616
	A.A. Mikhailichenko, D. L. Rubin Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	We are describing the latest results on fabrication and measurements of kicker and pulser and beam dynamics in E-989 experiment at FERMILAB on precise measurement of anomalous magnetic moment of muon.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA073
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Paper

Title

Page

Using Sloppy Models for Constrained Emittance Minimization at the Cornell Electron Storage Ring (CESR)

2418

W.F. Bergan, A.C. Bartnik, I.V. Bazarov, H. He, D. L. Rubin
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
J.P. Sethna
Cornell University, Ithaca, New York, USA

Funding: DOE DE-SC0013571 NSF DGE-1144153
In order to minimize the emittance at the Cornell Electron Storage Ring (CESR), we measure and correct the orbit, dispersion, and transverse coupling of the beam.* However, this method is limited by finite measurement resolution of the dispersion, and so a new procedure must be used to further reduce the emittance due to dispersion. In order to achieve this, we use a method based upon the theory of sloppy models.** We use a model of the accelerator to create the Hessian matrix which encodes the effects of various corrector magnets on the vertical emittance. A singular value decomposition of this matrix yields the magnet combinations which have the greatest effect on the emittance. We can then adjust these magnet ‘‘knobs'' sequentially in order to decrease the dispersion and the emittance. We present here comparisons of the effectiveness of this procedure in both experiment and simulation using a variety of CESR lattices. We also discuss techniques to minimize changes to parameters we have already corrected.
* J. Shanks, D.L. Rubin, and D. Sagan, Phys. Rev. ST Accel. Beams 17, 044003 (2014).
** K.S. Brown and J.P. Sethna, Phys. Rev. E 68, 021904 (2003).

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA136

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WEPIK109

Experimental Study of Vertical-Longitudinal Coupling Induced by Wakefields at CesrTA

3200

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

Funding: Work supported by NSF PHY-1416318, PHYS-1068662
Transverse vertical wakefields can cause vertical beam size growth in accelerators. Here we report recent measurements and simulations of wakefields from movable scrapers at the CesrTA. The charge dependent vertical beam size growth was observed while a single scraper was inserted through the top of the chamber. No change in the beam size was observed with top and bottom scrapers inserted symmetrically. The apparent growth in the vertical beam size was due in large part to the y-z coupling (vertical crabbing) induced by the monopole wake of the asymmetric scraper configuration. We explored this y-z coupling by varying vertical betatron phase advance between the vertical beam size monitor and the scrapers. In addition, we found that existing residual, current independent y-z coupling could be compensated by the scraper wake. Predictions of a tracking simulation are in good agreement with the measurements.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK109

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

WEPIK110

Resistive Wall Instability and Impedance Studies of Narrow Undulator Chamber in CHESS-U

3204

S. Wang, M.G. Billing, S. Poprocki, D. L. Rubin, D. Sagan
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: Work supported by NSF DMR-0936384 and NSF DMR-1332208
In a major upgrade of the Cornell Electron Storage Ring (CESR) one sextant of ring will be replaced with double bend achromats (DBAs) and undulator straights for x-ray users. The resistive wall impedance from the narrow gap (4.5 mm) undulator chambers (5 m per straight) may limit total beam. Here we report recent results of modelling and calculation of multibunch instabilities due to the impedance of chamber walls and transition tapers. The short range wakefields and resistive wall impedance are modelled and incorporated in a tracking simulation. The coupled-bunch growth rate found with the tracking study is in good agreement with the analytic approximation. We find that the resistive wall instability can be readily damped by our existing bunch-by-bunch feedback system.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK110

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THPVA073

Latest Results on Fast Kicker for g-2 E-989 Experiment at Fermilab

4616

A.A. Mikhailichenko, D. L. Rubin
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

We are describing the latest results on fabrication and measurements of kicker and pulser and beam dynamics in E-989 experiment at FERMILAB on precise measurement of anomalous magnetic moment of muon.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA073

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