IPAC2019 - List of Authors (Raubenheimer, T.O.)

Paper	Title	Page
TUPRB062	Coherence Time Characterization for Self-Amplified Spontaneous Emission Free-Electron Lasers	1820
	G. Zhou, Y. Jiao, J.Q. Wang IHEP, Beijing, People’s Republic of China T.O. Raubenheimer, J. Wu SLAC, Menlo Park, California, USA C.-Y. Tsai HUST, Wuhan, People’s Republic of China C. Yang USTC/NSRL, Hefei, Anhui, People’s Republic of China
	One of the key challenges in scientific researches based on free-electron lasers (FELs) is the characterization of the coherence time of the ultra-fast hard x-ray pulse, which fundamentally influences the interaction process between x-ray and materials. Conventional optical methods, based on autocorrelation, is very difficult to realize due to the lack of mirrors. Here, we experimentally demonstrate a conceptually new coherence time characterization method and a coherence time of 174.7 attoseonds has been measured for the 6.92 keV FEL pulses at Linac Coherent Light Source. In our experiment, a phase shifter is adopted to control the cross-correlation between x-ray and microbunched electrons. This approach provides critical temporal coherence diagnostics for x-ray FELs, and is decoupled from machine parameters, applicable for any photon energy, radiation brightness, repetition rate and FEL pulse duration, etc. The work was supported by the US Department of Energy (DOE) under contract DE-AC02-76SF00515 and the US DOE Office of Science Early Career Research Program grant FWP-2013-SLAC-100164.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB062
About •	paper received ※ 01 May 2019 paper accepted ※ 28 May 2019 issue date ※ 21 June 2019
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TUPRB089	Undulator Radiation Generated by a Single Electron	1867
	A. Halavanau, Z. Huang, C. Pellegrini, T.O. Raubenheimer SLAC, Menlo Park, California, USA I. Lobach University of Chicago, Chicago, Illinois, USA S. Nagaitsev Fermilab, Batavia, Illinois, USA D. Seipt HZDR, Dresden, Germany
	Funding: This work was supported by the U.S. Department of Energy Contract No. DE-AC02-76SF00515. The facilities providing single electron beams are currently being commissioned at Fermilab and will be at SLAC. Recently, Fermilab’s IOTA ring routinely demonstrated circulation of a single electron at 100 MeV beam energy. Alternatively, SLAC is working on constructing LCLS-II an X-ray FEL driven by a 4 GeV SRF linac. A parasitic beamline, S30XL, is planned that will extract 4 GeV dark current from between the primary LCLS-II electron bunches. The dark current will be delivered to End Station A and can work independently of LCLS-II experiments. The dark current will be bunched at a frequency of 46 MHz while extracted current varied from single electrons to 10’s of nA. In the present paper, we estimate the feasibility of propagating single electron beams through a conventional undulator, placed in the IOTA and S30XL beamlines. We explore the possible observable effects and experimental parameters range. In addition, we focus on potential applications of such beams in systems for high fidelity quantum measurements.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB089
About •	paper received ※ 13 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
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TUPRB096	Test of an X-ray Cavity using Double-Bunches from the LCLS Cu-Linac	1887
	K.-J. Kim, L. Assoufid, R.R. Lindberg, X. Shi, D. Shu, Yu. Shvyd’ko, M. White ANL, Argonne, Illinois, USA F.-J. Decker, Z. Huang, G. Marcus, T.O. Raubenheimer, D. Zhu SLAC, Menlo Park, California, USA
	Funding: This work is supported by U.S. DOE, Office of Science, Office of BES, under Contract No. DE-AC02-06CH11357 (ANL) and DE-AC02-76SF00515 (SLAC). We discuss a proposal to test the operation of an X-ray cavity consisting of Bragg reflectors. The test will con-stitute a major step demonstrating the feasibility of either an X-ray regenerative amplifier FEL or an X-ray FEL Oscillator. These cavity-based X-ray FELs will provide the full temporal coherence lacking in the SA-SE FELs. An X-ray cavity of rectangular path will be constructed around the first seven LCLS-II undulator units. The Cu-linac will produce a pair of electron bunches separated by the cavity-round-trip distance during each linac cycle. The X-ray pulse produced by the first bunch is deflected into the cavity and returns to the undulator where it is amplified due to the presence of the second bunch. The key challenges are: the preci-sion of the cavity mechanical construction, the quality of the diamond crystals, and the electron beam stability. When the LCLS-II super-conducting linac becomes available, the cavity can then be used for high-repetition rate studies of the X-ray RAFEL and XFELO concepts.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB096
About •	paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
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WEPMP049	Simulations of Beam Shaping for Dark Matter Experiments at LCLS-II	2443
	Y.M. Nosochkov, C. Hast, T.W. Markiewicz, L.Y. Nicolas, T.O. Raubenheimer, M. Santana-Leitner SLAC, Menlo Park, California, USA
	Funding: * Work supported by the U.S. DOE Contract DE-AC02-76SF00515. A new transfer beamline, called S30XL, and an experimental facility are proposed to be built at SLAC, taking advantage of the LCLS-II free electron laser (FEL) under construction. The S30XL will operate parasitically to the FEL by extracting the unused low intensity 4-GeV LCLS-II bunches into the existing A-line and the End Station-A (ESA). This provides a unique capability of multi-GeV nearly continuous electron beam for a variety of HEP experiments, in particular the dark matter search experiments. The latter require a very low beam current ranging from pA to micro-A, as well as a large beam spot at the detector. The necessary beam shaping will be performed using spoilers and collimators in the A-line, and by optimizing the optics. FLUKA and elegant codes are used to generate and track the beam into the ESA.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPMP049
About •	paper received ※ 16 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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WEPTS093	Emittance Preservation for LCLS-II-HE Project	3333
	J. Wu, T.O. Raubenheimer, M.D. Woodley SLAC, Menlo Park, California, USA J. Qiang LBNL, Berkeley, California, USA
	Funding: The work was supported by the US Department of Energy (DOE) under contract DE-AC02-76SF00515 and the US DOE Office of Science Early Career Research Program grant FWP-2013-SLAC-100164. A small transverse slice emittance at the undulator entrance is essential for high performance of the free electron laser. To achieve this, preservation of the phase space density of the electron bunch during acceleration and compression is absolutely necessary. The LCLS-II-HE is designed to transport a 100 pC bunch with an emittance of ~0.3 mm-mrad with minimal emittance dilution. However, in simulations starting from a normalized emittance on the order of 0.1 mm-mrad, the emittance growth is significant. In this paper, the sources of emittance growth are studied along the accelerator, in particular, around the laser-heater, the two bunch compressors. We have investigated mechanisms of emittance growth such as space charge, coherent synchrotron radiation, chromatic aberration, and spurious dispersion. Due to the extremely small emittance from the injector, 3-D space charge effect is important to determine the space charge dominated region and emittance dominated region. With this understanding, emittance preservation schemes are proposed. Studies are carried out with IMPACT simulation code, as well as ASTRA and ELEGANT.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS093
About •	paper received ※ 23 May 2019 paper accepted ※ 24 May 2019 issue date ※ 21 June 2019
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THPGW087	Transverse Jitter Tolerance Issues for Beam-Driven Plasma Accelerators	3774
	G.R. White, T.O. Raubenheimer SLAC, Menlo Park, California, USA
	Funding: Work supported by the Department of Energy under Contract Number: DE-AC02-76SF00515. Transverse jitter tolerances are considered for beam-driven plasma accelerators. A simple model for jitter transfer from the drive to witness beam is developed and concrete examples are studied for: high-brightness witness bunch injectors; high-energy boosters for FEL’s; and future Linear Colliders. Compared with an existing PWFA driver facility ([,]), the calculated tolerances are 18X ’ 170X tighter than achievable, even considering any upgrades with existing technology. Nature 445 741 Feb 2007, Nature 515, Nov. 2014 ** FACET-II Technical Design Report, SLAC-R-1072, "The FLASHForward facility at DESY", NIMA Oct., 2015
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPGW087
About •	paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Coherence Time Characterization for Self-Amplified Spontaneous Emission Free-Electron Lasers

1820

G. Zhou, Y. Jiao, J.Q. Wang
IHEP, Beijing, People’s Republic of China
T.O. Raubenheimer, J. Wu
SLAC, Menlo Park, California, USA
C.-Y. Tsai
HUST, Wuhan, People’s Republic of China
C. Yang
USTC/NSRL, Hefei, Anhui, People’s Republic of China

One of the key challenges in scientific researches based on free-electron lasers (FELs) is the characterization of the coherence time of the ultra-fast hard x-ray pulse, which fundamentally influences the interaction process between x-ray and materials. Conventional optical methods, based on autocorrelation, is very difficult to realize due to the lack of mirrors. Here, we experimentally demonstrate a conceptually new coherence time characterization method and a coherence time of 174.7 attoseonds has been measured for the 6.92 keV FEL pulses at Linac Coherent Light Source. In our experiment, a phase shifter is adopted to control the cross-correlation between x-ray and microbunched electrons. This approach provides critical temporal coherence diagnostics for x-ray FELs, and is decoupled from machine parameters, applicable for any photon energy, radiation brightness, repetition rate and FEL pulse duration, etc.
The work was supported by the US Department of Energy (DOE) under contract DE-AC02-76SF00515 and the US DOE Office of Science Early Career Research Program grant FWP-2013-SLAC-100164.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB062

About •

paper received ※ 01 May 2019 paper accepted ※ 28 May 2019 issue date ※ 21 June 2019

Export •

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

TUPRB089

Undulator Radiation Generated by a Single Electron

1867

A. Halavanau, Z. Huang, C. Pellegrini, T.O. Raubenheimer
SLAC, Menlo Park, California, USA
I. Lobach
University of Chicago, Chicago, Illinois, USA
S. Nagaitsev
Fermilab, Batavia, Illinois, USA
D. Seipt
HZDR, Dresden, Germany

Funding: This work was supported by the U.S. Department of Energy Contract No. DE-AC02-76SF00515.
The facilities providing single electron beams are currently being commissioned at Fermilab and will be at SLAC. Recently, Fermilab’s IOTA ring routinely demonstrated circulation of a single electron at 100 MeV beam energy. Alternatively, SLAC is working on constructing LCLS-II an X-ray FEL driven by a 4 GeV SRF linac. A parasitic beamline, S30XL, is planned that will extract 4 GeV dark current from between the primary LCLS-II electron bunches. The dark current will be delivered to End Station A and can work independently of LCLS-II experiments. The dark current will be bunched at a frequency of 46 MHz while extracted current varied from single electrons to 10’s of nA. In the present paper, we estimate the feasibility of propagating single electron beams through a conventional undulator, placed in the IOTA and S30XL beamlines. We explore the possible observable effects and experimental parameters range. In addition, we focus on potential applications of such beams in systems for high fidelity quantum measurements.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB089

About •

paper received ※ 13 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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

TUPRB096

Test of an X-ray Cavity using Double-Bunches from the LCLS Cu-Linac

1887

K.-J. Kim, L. Assoufid, R.R. Lindberg, X. Shi, D. Shu, Yu. Shvyd’ko, M. White
ANL, Argonne, Illinois, USA
F.-J. Decker, Z. Huang, G. Marcus, T.O. Raubenheimer, D. Zhu
SLAC, Menlo Park, California, USA

Funding: This work is supported by U.S. DOE, Office of Science, Office of BES, under Contract No. DE-AC02-06CH11357 (ANL) and DE-AC02-76SF00515 (SLAC).
We discuss a proposal to test the operation of an X-ray cavity consisting of Bragg reflectors. The test will con-stitute a major step demonstrating the feasibility of either an X-ray regenerative amplifier FEL or an X-ray FEL Oscillator. These cavity-based X-ray FELs will provide the full temporal coherence lacking in the SA-SE FELs. An X-ray cavity of rectangular path will be constructed around the first seven LCLS-II undulator units. The Cu-linac will produce a pair of electron bunches separated by the cavity-round-trip distance during each linac cycle. The X-ray pulse produced by the first bunch is deflected into the cavity and returns to the undulator where it is amplified due to the presence of the second bunch. The key challenges are: the preci-sion of the cavity mechanical construction, the quality of the diamond crystals, and the electron beam stability. When the LCLS-II super-conducting linac becomes available, the cavity can then be used for high-repetition rate studies of the X-ray RAFEL and XFELO concepts.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB096

About •

paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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

WEPMP049

Simulations of Beam Shaping for Dark Matter Experiments at LCLS-II

2443

Y.M. Nosochkov, C. Hast, T.W. Markiewicz, L.Y. Nicolas, T.O. Raubenheimer, M. Santana-Leitner
SLAC, Menlo Park, California, USA

Funding: * Work supported by the U.S. DOE Contract DE-AC02-76SF00515.
A new transfer beamline, called S30XL, and an experimental facility are proposed to be built at SLAC, taking advantage of the LCLS-II free electron laser (FEL) under construction. The S30XL will operate parasitically to the FEL by extracting the unused low intensity 4-GeV LCLS-II bunches into the existing A-line and the End Station-A (ESA). This provides a unique capability of multi-GeV nearly continuous electron beam for a variety of HEP experiments, in particular the dark matter search experiments. The latter require a very low beam current ranging from pA to micro-A, as well as a large beam spot at the detector. The necessary beam shaping will be performed using spoilers and collimators in the A-line, and by optimizing the optics. FLUKA and elegant codes are used to generate and track the beam into the ESA.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPMP049

About •

paper received ※ 16 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)

WEPTS093

Emittance Preservation for LCLS-II-HE Project

3333

J. Wu, T.O. Raubenheimer, M.D. Woodley
SLAC, Menlo Park, California, USA
J. Qiang
LBNL, Berkeley, California, USA

Funding: The work was supported by the US Department of Energy (DOE) under contract DE-AC02-76SF00515 and the US DOE Office of Science Early Career Research Program grant FWP-2013-SLAC-100164.
A small transverse slice emittance at the undulator entrance is essential for high performance of the free electron laser. To achieve this, preservation of the phase space density of the electron bunch during acceleration and compression is absolutely necessary. The LCLS-II-HE is designed to transport a 100 pC bunch with an emittance of ~0.3 mm-mrad with minimal emittance dilution. However, in simulations starting from a normalized emittance on the order of 0.1 mm-mrad, the emittance growth is significant. In this paper, the sources of emittance growth are studied along the accelerator, in particular, around the laser-heater, the two bunch compressors. We have investigated mechanisms of emittance growth such as space charge, coherent synchrotron radiation, chromatic aberration, and spurious dispersion. Due to the extremely small emittance from the injector, 3-D space charge effect is important to determine the space charge dominated region and emittance dominated region. With this understanding, emittance preservation schemes are proposed. Studies are carried out with IMPACT simulation code, as well as ASTRA and ELEGANT.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS093

About •

paper received ※ 23 May 2019 paper accepted ※ 24 May 2019 issue date ※ 21 June 2019

Export •

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

THPGW087

Transverse Jitter Tolerance Issues for Beam-Driven Plasma Accelerators

3774

G.R. White, T.O. Raubenheimer
SLAC, Menlo Park, California, USA

Funding: Work supported by the Department of Energy under Contract Number: DE-AC02-76SF00515.
Transverse jitter tolerances are considered for beam-driven plasma accelerators. A simple model for jitter transfer from the drive to witness beam is developed and concrete examples are studied for: high-brightness witness bunch injectors; high-energy boosters for FEL’s; and future Linear Colliders. Compared with an existing PWFA driver facility ([*,**]), the calculated tolerances are 18X ’ 170X tighter than achievable, even considering any upgrades with existing technology.
* Nature 445 741 Feb 2007, Nature 515, Nov. 2014
** FACET-II Technical Design Report, SLAC-R-1072, "The FLASHForward facility at DESY", NIMA Oct., 2015

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPGW087

About •

paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

Export •

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