IPAC2019 - List of Authors (Rose, J.)

Paper	Title	Page
MOPGW125	Lossless Crossing of 1/2 Resonance Stopband by Synchrotron Oscillations	410
	G.M. Wang, Y. Li, J. Rose, T.V. Shaftan, V.V. Smaluk BNL, Upton, Long Island, New York, USA
	Funding: DOE under contract No.DE-AC02- 98CH10886 Modern high performance circular accelerators require sophisticated corrections of nonlinear lattices. The beam betatron tune footprint may cross many resonances, reducing dynamic aperture and causing particle loss. However, if particles cross a resonance reasonably fast, the beam deterioration may be minimized. In this paper, we present the experiments with the beam passing through a half-integer resonance stopband via chromatic tune modulation by exciting synchrotron oscillations. This is the first time that beam dynamics have been kept under precise control while the beam crosses a half-integer resonance. Our results convincingly demonstrate that particles can cross the half-integer resonance without being lost if the passage is reasonably fast and the resonance stopband is sufficiently narrow.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW125
About •	paper received ※ 13 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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WEPGW102	Investigation on Mysterious Long-Term Orbit Drift at NSLS-II	2728
	Y. Hidaka, W.X. Cheng, L. Doom, R.P. Fliller, G. Ganetis, J. Gosman, C. Hetzel, R.A. Hubbard, D. Padrazo Jr, B. Podobedov, J. Rose, T.V. Shaftan, S.K. Sharma, V.V. Smaluk, T. Tanabe, Y. Tian, G.M. Wang, C.H. Yu BNL, Upton, Long Island, New York, USA
	Funding: The study is supported by U.S. DOE under Contract No. DE-SC0012704. Over a few months in 2018, we observed occasional episodes of relatively quick accumulation of correction strengths for the fast correctors (used by the fast orbit feedback) near Cell 4 (C04) region at NSLS-II Storage Ring. We immediately started investigating the problem, but the cause remained unclear. However, after coming back from the Fall shutdown, we experienced even faster drifts, at a rate of as much as 10 urad per day in terms of orbit kick angle accumulation. The risk of damage on the ring vacuum chambers by the continuing orbit drift without explanation eventually forced us to take emergency study shifts and temporarily lock out the C04 IVU beamline. After extensive investigation by many subsystem experts in Accelerator Division, ruling out many suspicious sources one by one, we were finally able to conclude the cause to be the localized ground motion induced by large temperature jumps of the utility tunnel right underneath the C04 straight section. We report the details of this incident.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW102
About •	paper received ※ 19 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Lossless Crossing of 1/2 Resonance Stopband by Synchrotron Oscillations

410

G.M. Wang, Y. Li, J. Rose, T.V. Shaftan, V.V. Smaluk
BNL, Upton, Long Island, New York, USA

Funding: DOE under contract No.DE-AC02- 98CH10886
Modern high performance circular accelerators require sophisticated corrections of nonlinear lattices. The beam betatron tune footprint may cross many resonances, reducing dynamic aperture and causing particle loss. However, if particles cross a resonance reasonably fast, the beam deterioration may be minimized. In this paper, we present the experiments with the beam passing through a half-integer resonance stopband via chromatic tune modulation by exciting synchrotron oscillations. This is the first time that beam dynamics have been kept under precise control while the beam crosses a half-integer resonance. Our results convincingly demonstrate that particles can cross the half-integer resonance without being lost if the passage is reasonably fast and the resonance stopband is sufficiently narrow.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW125

About •

paper received ※ 13 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

Export •

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

WEPGW102

Investigation on Mysterious Long-Term Orbit Drift at NSLS-II

2728

Y. Hidaka, W.X. Cheng, L. Doom, R.P. Fliller, G. Ganetis, J. Gosman, C. Hetzel, R.A. Hubbard, D. Padrazo Jr, B. Podobedov, J. Rose, T.V. Shaftan, S.K. Sharma, V.V. Smaluk, T. Tanabe, Y. Tian, G.M. Wang, C.H. Yu
BNL, Upton, Long Island, New York, USA

Funding: The study is supported by U.S. DOE under Contract No. DE-SC0012704.
Over a few months in 2018, we observed occasional episodes of relatively quick accumulation of correction strengths for the fast correctors (used by the fast orbit feedback) near Cell 4 (C04) region at NSLS-II Storage Ring. We immediately started investigating the problem, but the cause remained unclear. However, after coming back from the Fall shutdown, we experienced even faster drifts, at a rate of as much as 10 urad per day in terms of orbit kick angle accumulation. The risk of damage on the ring vacuum chambers by the continuing orbit drift without explanation eventually forced us to take emergency study shifts and temporarily lock out the C04 IVU beamline. After extensive investigation by many subsystem experts in Accelerator Division, ruling out many suspicious sources one by one, we were finally able to conclude the cause to be the localized ground motion induced by large temperature jumps of the utility tunnel right underneath the C04 straight section. We report the details of this incident.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW102

About •

paper received ※ 19 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

Export •

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