IPAC2013 - List of Authors (White, G.R.)

Paper	Title	Page
MOPWA052	Short Range Wakefield Measurements of High Resolution RF Cavity Beam Position Monitors at ATF2	792
	J. Snuverink, S.T. Boogert, F.J. Cullinan, Y.I. Kim, A. Lyapin JAI, Egham, Surrey, United Kingdom K. Kubo, T. Okugi, T. Tauchi, N. Terunuma, J. Urakawa KEK, Ibaraki, Japan G.R. White SLAC, Menlo Park, California, USA
	Cavity beam position monitors (CBPM) have been used in several accelerator facilities and are planned to be used in future accelerators and light sources. High position resolution up to tens of nanometres has been achieved, but short range wakefields are a concern, especially for small beam emittances. This paper presents the wakefield calculations as well as the first measurements of the CBPM-generated short range wakefields performed at the Accelerator Test Facility (ATF2).

MOPWA058	Cavity Beam Position Monitor at Interaction Point Region of Accelerator Test Facility 2	807
	Y.I. Kim, D.R. Bett, N. Blaskovic Kraljevic, P. Burrows, G.B. Christian, M.R. Davis, A. Lyapin JAI, Egham, Surrey, United Kingdom S.T. Boogert Royal Holloway, University of London, Surrey, United Kingdom J.C. Frisch, D.J. McCormick, J. Nelson, G.R. White SLAC, Menlo Park, California, USA Y. Honda, T. Tauchi, N. Terunuma, J. Urakawa KEK, Ibaraki, Japan
	Nanometre resolution cavity beam position monitors (BPMs) have been developed to measure the beam position and linked to a feedback system control the beam position stability within few nanometres in the vertical direction at the focus, or interaction point (IP), of Accelerator Test Facility 2 (ATF2). In addition, for feedback applications a lower-Q and hence faster decay time system is desirable. Two IPBPMs have been installed inside of IP chamber at the ATF2 focus area. To measure the resolution of IPBPMs two additional C-band cavity BPMs have been installed one upstream and one downstream of the IP. One cavity BPM has been installed at an upstream image point of IP. The performance of the BPMs is discussed and the correlation between IP and image point positions is presented along with a discussion of using these BPMs for position stabilisation at the IP.

MOPWO023	Upgrade and Systematic Measurement Campaign of the ATF2 Multi-OTR System	933
	A. Faus-Golfe, J. Alabau-Gonzalvo, C. Blanch Gutierrez, J. Resta-López IFIC, Valencia, Spain J. Cruz, E. Marín, D.J. McCormick, G.R. White, M. Woodley SLAC, Menlo Park, California, USA
	A multi-Optical Transition Radiation (mOTR) system made of four stations is being used routinely since September 2011 for transverse beam size measurement and emittance reconstruction in the extraction line of ATF2, providing diagnostic support during the ATF2 tuning operation. Furthermore it is also an excellent tool for fast transverse coupling correction. Due to the compactness of the current design the system has an influence in the increase of the transverse emittance due to wakefield effects when a simultaneous measurement is made. To avoid this effect a new target holder and a new optics has been designed and implemented. In this paper we describe the present status of the ATF2 mOTR system, showing recent performance results, and hardware design improvements.

TUPWO017	Simulation on the Breaking of αx Multiknob Orthogonality in the Presence of Gradient and Coupling Errors and Experimental Investigation	1919
	S. Bai, J. Gao IHEP, Beijing, People's Republic of China P. Bambade LAL, Orsay, France G.R. White SLAC, Menlo Park, California, USA
	The ATF2 project is the final focus system prototype for ILC and CLIC linear collider projects, with a purpose to reach a 37nm vertical beam size at the interaction point. In beam tuning towards the goal beam size, the presence of a tilt of the IP Shintake monitor fringe pattern with respect to the x-y coordinate system of the beam can break the orthogonality in the main σ34 and σ32 waist corrections required to reduce the vertical beam size at IP. Concerning the method of doing αx scan and measuring the vertical beam size to diagnose the IPBSM fringe tilt or residual σ13, one thing should be studied is to check what could break the orthogonality of the αx knob other than σ13 and the IPBSM fringe tilt. In this paper, we report on the simulation study that check for the breaking of orthogonality of the αx knob in the presence of gradient and coupling errors; to what extent this breaking of orthogonality can go; and also calculate the IPBSM fringe tilt angle from experiment results.

TUPWO067	Start-to-end Particle Tracking of the FACET Accelerator	2018
	N. Lipkowitz, F.-J. Decker, G.R. White, M. Woodley, G. Yocky SLAC, Menlo Park, California, USA
	Funding: Work supported by Department of Energy contract DE-AC02-76SF00515. The Facility for Advanced aCcelerator Experimental Tests (FACET) consists of the first two-thirds of the SLAC two-mile linac followed by a final focus and experimental end station. To date, wakefield-dominated emittance growth and dispersion in the linac, as well as dispersive and chromatic effects in the final focus have precluded regular reliable operation that meets the design parameters for final spot size. In this work, a 6-D particle tracking code (Lucretia) is used to simulate the complete machine, with input parameters taken directly from saved machine configurations. Sensitivities of various tuning parameters to the final spot sizes are compared with measurements taken from the real machine, and a set of tuning protocols is determined to improve regular machine operation.

TUPWO068	Performance Improvements of the SLAC Linac for the FACET Beam	2021
	F.-J. Decker, N. Lipkowitz, E. Marín, Y. Nosochkov, J. Sheppard, M.K. Sullivan, Y. Sun, M.-H. Wang, G.R. White, U. Wienands, M. Woodley, G. Yocky SLAC, Menlo Park, California, USA
	Funding: Work supported by U.S.Department of Energy, Contract DE-AC02-76SF00515. Two thirds of the SLAC Linac is used to generate a short, intense electron beam for the FACET experiments. The emittance growth along the Linac is a major concern to finally get small spot sizes for these experiments. There are two different approaches to get the required small emittances: a) lengthy iterative global tuning technique, and b) trying to identify locations of the main sources of the emittance growth and reducing their effect locally. How these approaches help to get good beam performances is discussed.

TUPWO069	Optimization of FACET Optics	2024
	M.-H. Wang, F.-J. Decker, N. Lipkowitz, Y. Nosochkov, G.R. White, U. Wienands, M. Woodley, G. Yocky SLAC, Menlo Park, California, USA
	Funding: supported by the US Department of Energy contract DE-AC02-76SF00515. The FACET accelerator facility is designed to provide short and intense e^- or e⁺ bunches with small spot size for plasma wakefield accelerator research and other experiments. It is based on the SLAC linac with a compressor chicane in sector-10, and a second compressor chicane and final focus in sector-20 (S20). Originally, the S20 chicane was designed to be compatible with an upgrade to include a second S20 chicane for simultaneous transport of e^- and e⁺ bunches. This placed additional optics constraints which lead to strong focusing in the S20 chicane. The latter increases the effects of errors causing emittance growth. Lately, it has been decided not to proceed with the upgrade option. Therefore, there is a potential for improving the optics by relaxing the constraints. In this study, we explore alternative optics designs where beta functions in the S20 chicane and final focus are reduced in order to minimize the error effects. The optics and non-linear aberrations are evaluated, and the chromatic correction is optimized for each design. Beam tracking simulations are performed using Elegant and Lucretia. The most optimal designs are identified based on these simulations.

Paper

Title

Page

Short Range Wakefield Measurements of High Resolution RF Cavity Beam Position Monitors at ATF2

792

J. Snuverink, S.T. Boogert, F.J. Cullinan, Y.I. Kim, A. Lyapin
JAI, Egham, Surrey, United Kingdom
K. Kubo, T. Okugi, T. Tauchi, N. Terunuma, J. Urakawa
KEK, Ibaraki, Japan
G.R. White
SLAC, Menlo Park, California, USA

Cavity beam position monitors (CBPM) have been used in several accelerator facilities and are planned to be used in future accelerators and light sources. High position resolution up to tens of nanometres has been achieved, but short range wakefields are a concern, especially for small beam emittances. This paper presents the wakefield calculations as well as the first measurements of the CBPM-generated short range wakefields performed at the Accelerator Test Facility (ATF2).

MOPWA058

Cavity Beam Position Monitor at Interaction Point Region of Accelerator Test Facility 2

807

Y.I. Kim, D.R. Bett, N. Blaskovic Kraljevic, P. Burrows, G.B. Christian, M.R. Davis, A. Lyapin
JAI, Egham, Surrey, United Kingdom
S.T. Boogert
Royal Holloway, University of London, Surrey, United Kingdom
J.C. Frisch, D.J. McCormick, J. Nelson, G.R. White
SLAC, Menlo Park, California, USA
Y. Honda, T. Tauchi, N. Terunuma, J. Urakawa
KEK, Ibaraki, Japan

Nanometre resolution cavity beam position monitors (BPMs) have been developed to measure the beam position and linked to a feedback system control the beam position stability within few nanometres in the vertical direction at the focus, or interaction point (IP), of Accelerator Test Facility 2 (ATF2). In addition, for feedback applications a lower-Q and hence faster decay time system is desirable. Two IPBPMs have been installed inside of IP chamber at the ATF2 focus area. To measure the resolution of IPBPMs two additional C-band cavity BPMs have been installed one upstream and one downstream of the IP. One cavity BPM has been installed at an upstream image point of IP. The performance of the BPMs is discussed and the correlation between IP and image point positions is presented along with a discussion of using these BPMs for position stabilisation at the IP.

MOPWO023

Upgrade and Systematic Measurement Campaign of the ATF2 Multi-OTR System

933

A. Faus-Golfe, J. Alabau-Gonzalvo, C. Blanch Gutierrez, J. Resta-López
IFIC, Valencia, Spain
J. Cruz, E. Marín, D.J. McCormick, G.R. White, M. Woodley
SLAC, Menlo Park, California, USA

A multi-Optical Transition Radiation (mOTR) system made of four stations is being used routinely since September 2011 for transverse beam size measurement and emittance reconstruction in the extraction line of ATF2, providing diagnostic support during the ATF2 tuning operation. Furthermore it is also an excellent tool for fast transverse coupling correction. Due to the compactness of the current design the system has an influence in the increase of the transverse emittance due to wakefield effects when a simultaneous measurement is made. To avoid this effect a new target holder and a new optics has been designed and implemented. In this paper we describe the present status of the ATF2 mOTR system, showing recent performance results, and hardware design improvements.

TUPWO017

Simulation on the Breaking of αx Multiknob Orthogonality in the Presence of Gradient and Coupling Errors and Experimental Investigation

1919

S. Bai, J. Gao
IHEP, Beijing, People's Republic of China
P. Bambade
LAL, Orsay, France
G.R. White
SLAC, Menlo Park, California, USA

The ATF2 project is the final focus system prototype for ILC and CLIC linear collider projects, with a purpose to reach a 37nm vertical beam size at the interaction point. In beam tuning towards the goal beam size, the presence of a tilt of the IP Shintake monitor fringe pattern with respect to the x-y coordinate system of the beam can break the orthogonality in the main σ34 and σ32 waist corrections required to reduce the vertical beam size at IP. Concerning the method of doing αx scan and measuring the vertical beam size to diagnose the IPBSM fringe tilt or residual σ13, one thing should be studied is to check what could break the orthogonality of the αx knob other than σ13 and the IPBSM fringe tilt. In this paper, we report on the simulation study that check for the breaking of orthogonality of the αx knob in the presence of gradient and coupling errors; to what extent this breaking of orthogonality can go; and also calculate the IPBSM fringe tilt angle from experiment results.

TUPWO067

Start-to-end Particle Tracking of the FACET Accelerator

2018

N. Lipkowitz, F.-J. Decker, G.R. White, M. Woodley, G. Yocky
SLAC, Menlo Park, California, USA

Funding: Work supported by Department of Energy contract DE-AC02-76SF00515.
The Facility for Advanced aCcelerator Experimental Tests (FACET) consists of the first two-thirds of the SLAC two-mile linac followed by a final focus and experimental end station. To date, wakefield-dominated emittance growth and dispersion in the linac, as well as dispersive and chromatic effects in the final focus have precluded regular reliable operation that meets the design parameters for final spot size. In this work, a 6-D particle tracking code (Lucretia) is used to simulate the complete machine, with input parameters taken directly from saved machine configurations. Sensitivities of various tuning parameters to the final spot sizes are compared with measurements taken from the real machine, and a set of tuning protocols is determined to improve regular machine operation.

TUPWO068

Performance Improvements of the SLAC Linac for the FACET Beam

2021

F.-J. Decker, N. Lipkowitz, E. Marín, Y. Nosochkov, J. Sheppard, M.K. Sullivan, Y. Sun, M.-H. Wang, G.R. White, U. Wienands, M. Woodley, G. Yocky
SLAC, Menlo Park, California, USA

Funding: Work supported by U.S.Department of Energy, Contract DE-AC02-76SF00515.
Two thirds of the SLAC Linac is used to generate a short, intense electron beam for the FACET experiments. The emittance growth along the Linac is a major concern to finally get small spot sizes for these experiments. There are two different approaches to get the required small emittances: a) lengthy iterative global tuning technique, and b) trying to identify locations of the main sources of the emittance growth and reducing their effect locally. How these approaches help to get good beam performances is discussed.

TUPWO069

Optimization of FACET Optics

2024

M.-H. Wang, F.-J. Decker, N. Lipkowitz, Y. Nosochkov, G.R. White, U. Wienands, M. Woodley, G. Yocky
SLAC, Menlo Park, California, USA

Funding: supported by the US Department of Energy contract DE-AC02-76SF00515.
The FACET accelerator facility is designed to provide short and intense e^- or e⁺ bunches with small spot size for plasma wakefield accelerator research and other experiments. It is based on the SLAC linac with a compressor chicane in sector-10, and a second compressor chicane and final focus in sector-20 (S20). Originally, the S20 chicane was designed to be compatible with an upgrade to include a second S20 chicane for simultaneous transport of e^- and e⁺ bunches. This placed additional optics constraints which lead to strong focusing in the S20 chicane. The latter increases the effects of errors causing emittance growth. Lately, it has been decided not to proceed with the upgrade option. Therefore, there is a potential for improving the optics by relaxing the constraints. In this study, we explore alternative optics designs where beta functions in the S20 chicane and final focus are reduced in order to minimize the error effects. The optics and non-linear aberrations are evaluated, and the chromatic correction is optimized for each design. Beam tracking simulations are performed using Elegant and Lucretia. The most optimal designs are identified based on these simulations.