IPAC2018 - List of Authors (Piot, P.)

Paper	Title	Page
TUPMF020	Demonstration of Fast, Single-shot Photocathode QE Mapping Method Using MLA Pattern Beam	1293
	E.E. Wisniewski, M.E. Conde, D.S. Doran, W. Gai, Q. Gao, W. Liu, J.G. Power, C. Whiteford ANL, Argonne, Illinois, USA Q. Gao TUB, Beijing, People's Republic of China G. Ha PAL, Pohang, Republic of Korea A. Halavanau, P. Piot Northern Illinois University, DeKalb, Illinois, USA P. Piot Fermilab, Batavia, Illinois, USA
	Funding: UChicago Argonne, LLC, Operator of Argonne National Laboratory ("Argonne"). Argonne, a U.S.A. Department of Energy Office of Science laboratory, is operated under Contract No. DE-AC02-06CH11357. Quantum efficiency (QE) is the chief figure of merit in the characterization of photocathodes. Semiconductor photocathodes, especially when used in high rep-rate photo-injectors, are known to show QE degradation over time and must be replaced. The total QE is the basic diagnostic which is used widely and is easy to obtain. However, a QE map indicating variations of QE across the cathode surface has greater utility. It can quickly diagnose problems of QE inhomogeneity. Most QE mapping techniques require hours to complete and are thus disruptive to a user facility schedule. A fast, single-shot method has been proposed (citation) using a micro-lens array (MLA) generated QE map. In this paper we report the implementation of the method at Argonne Wakefield Accelerator facility. A micro-lens array (MLA) is used to project an array of beamlets onto the photocathode. The resulting photoelectron beam in the form of an array of electron beamlets is imaged at a YAG screen. Four synchronized measurements are made and the results used to produce a QE map of the photocathode.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF020
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THPAK057	Simulations of Optical Stochastic Cooling with ELEGANT	3354
	M.B. Andorf, P. Piot Northern Illinois University, DeKalb, Illinois, USA V.A. Lebedev, V.A. Lebedev, P. Piot Fermilab, Batavia, Illinois, USA
	Fermilab is pursuing a proof-of-principle test of the Optical Stochastic Cooling (OSC) of 100 MeV electrons in the Integrable Optics Test Accelerator. In support of this we present simulations of horizontal damping with OSC. We find excellent agreement with theory on the amplitude dependent damping rates. Additionally particle tracking is used to confirm the necessity and effectiveness of sextupoles used to correct non-linear path lengthening in the OSC chicane.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK057
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THPAK058	Planned Detection and Amplification of Infared Synchrotron Radiation for Electron-Beam Diagnostics and Manipulations	3358
	M.B. Andorf, P. Piot Northern Illinois University, DeKalb, Illinois, USA P. Piot Fermilab, Batavia, Illinois, USA
	Amplification of beam-induced radiation (e.g. synchrotron or undulator radiation) is a necessary component of optical stochastic cooling of hadrons or heavy ions. We discuss a proposal to measure and amplify synchrotron radiation from a bending magnet of the Advanced Photon Source. The measurements will be in the short-wavelength infrared region (SWIR) and amplification will be accomplished using a pumped Chromium:Zinc Selenide (Cr:ZnSe) crystal with maximum gain at λ≅ 2.2~μm.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK058
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THPAK060	Transverse-to-Longitudinal Photocathode Distribution Imaging	3361
SUSPF084	use link to see paper's listing under its alternate paper code
	A. Halavanau, P. Piot Northern Illinois University, DeKalb, Illinois, USA W. Gai, G. Ha, J.G. Power, E.E. Wisniewski ANL, Argonne, Illinois, USA G. Ha PAL, Pohang, Republic of Korea P. Piot Fermilab, Batavia, Illinois, USA G. Qiang TUB, Beijing, People's Republic of China
	In this paper, we present a tunable picosecond-scale bunch train generation technique combining a microlens array (MLA) transverse laser shaper and a transverse-to-longitudinal emittance exchange (EEX) beamline. The modulated beamlet array is formed at the photocathode with the MLA setup. The resulting patterned electron beam is accelerated to 50 MeV and transported to the entrance of the EEX setup. A quadrupole channel is used to adjust the transverse spacing of the beamlet array upstream of the EEX, thereby enabling the generation of a bunch train with tunable separation downstream of the EEX beamline. Additionally, the MLA is mounted on a rotation stage which provides additional flexibility to produce high-frequency beam density modulation downstream of the EEX. Experimental results obtained at the Argonne Wakefield Accelerator (AWA) facility are presented and compared with numerical simulations.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK060
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THPAK061	Magnetized and Flat Beam Generation at the Fermilab's FAST Facility	3364
	A. Halavanau, P. Piot Northern Illinois University, DeKalb, Illinois, USA D.J. Crawford, D.R. Edstrom, D. Mihalcea, S. Nagaitsev, P. Piot, A.L. Romanov, J. Ruan, V.D. Shiltsev Fermilab, Batavia, Illinois, USA
	Funding: This work is supported by the DOE contract No.DEAC02-07CH11359 to the Fermi Research Alliance LLC. A.H. is supported by the DOE under contract No. DE-SC0011831 with Northern Illinois University. Canonical angular momentum (CAM) dominated beams can be formed in photoinjectors by applying an axial magnetic field on the photocathode surface. Such a beam possess asymmetric eigenemittances and is characterized by the measure of its magnetization. CAM removal using a set skew-quadrupole magnets maps the beam eigenemittances to the conventional emittance along each transverse degree of freedom thereby yielding flat beam with asymmetric transverse emittance. In this paper we report on the experimental generation of CAM dominated beam and their subsequent transformation into flat beams at the Fermilab Accelerator Science and Technology (FAST) facility. Our results are compared with numerical simulations and possible applications of the produced beams are discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK061
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THPAK062	Bunch Compression of Flat Beams	3368
	A. Halavanau, P. Piot Northern Illinois University, DeKalb, Illinois, USA D.J. Crawford, D.R. Edstrom, D. Mihalcea, S. Nagaitsev, P. Piot, A.L. Romanov, J. Ruan, V.D. Shiltsev Fermilab, Batavia, Illinois, USA
	Funding: This work is supported by the DOE contract No.DEAC02-07CH11359 to the Fermi Research Alliance LLC. A.H. is supported by the DOE under contract No. DE-SC0011831 with Northern Illinois University. Flat beams can be produced via a linear manipulation of canonical angular momentum (CAM) dominated beams using a set of skew-quadrupole magnets. Recently such beams were produced at Fermilab Accelerator Science and Technology (FAST) facility. In this paper, we report the results of flat beam compression study in a magnetic chicane at an energy of E~32 MeV. Additionally, we investigate the effect of energy chirp in the round-to-flat beam transform. The experimental results are compared with numerical simulations.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK062
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THPAK063	Electron Beam Pattern Rotation as a Method of Tunable Bunch Train Generation	3372
	A. Halavanau, P. Piot Northern Illinois University, DeKalb, Illinois, USA P. Piot Fermilab, Batavia, Illinois, USA
	Transversely modulated electron beams can be formed in photo injectors via microlens array (MLA) UV laser shaping technique. Micro lenses can be arranged in polygonal lattices, with resulting transverse electron beam modulation mimicking the lenses pattern. Conventionally, square MLAs are used for UV laser beam shaping, and generated electron beam patterns form square beamlet arrays. The MLA setup can be placed on a rotational mount, thereby rotating electron beam distribution. In combination with transverse-to-longitudinal emittance exchange beam line, it allows to vary beamlets horizontal projection and tune electron bunch train. In this paper, we extend the technique to the case of different MLA lattice arrangements and explore the benefits of its rotational symmetries.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK063
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THPAK065	Application of Transverse-to-Longitudinal Phase-Space-Exchanged Beam Produced from a Nano-Structure Photocathode to a Soft X-Ray Free-Electron Laser	3379
SUSPF085	use link to see paper's listing under its alternate paper code
	A. Lueangaramwong, P. Piot Northern Illinois University, DeKalb, Illinois, USA G. Andonian RadiaBeam, Santa Monica, California, USA P. Piot Fermilab, Batavia, Illinois, USA
	Nano-structured cathodes can form transversely modulated beams which can be subsequently converted to temporally modulated beam via a transverse-to-longitudinal phase space-exchanging beamline. We demonstrate via numerical simulation the generation of transversely modulated beam at the nm scale and investigate the corresponding enhancement in a soft-X-ray SASE free-electron laser. Our study is supported by start-to-end simulation combining WARP, IMPACT-T and GENESIS(FEL process) and focuses on the optimization of the beamline to preserve initial modulation at the nanometer level. We also discuss the scaling of the concept to shorter-wavelengths.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK065
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THPMF025	Emittance Measurements at FAST Facility	4100
	J. Ruan, D.R. Broemmelsiek, D.J. Crawford, A.L. Edelen, J.P. Edelen, D.R. Edstrom, A.H. Lumpkin, P. Piot, A.L. Romanov, R.M. Thurman-Keup Fermilab, Batavia, Illinois, USA P. Piot Northern Illinois University, DeKalb, Illinois, USA
	Funding: *Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy. The FAST facility at Fermilab recently been commissioned has demonstrated the generation of electron beam within a wide range of parameter (energy, charge) suitable for accelerator-science and beam-physics experiments. This accelerator consists of a photo-electron gun, injector, ILC-type cryomodules, and multiple downstream beam-lines. It will mainly serve as injector for the upcoming Integrable Optical Test Accelerator (IOTA). At the same time we will also carry out a LINAC based intense gamma ray experiment based on the Inverse Compton scattering. It is essential to understand the beam emittance for both experiments. A number of techniques are used to characaterizing the beam emittance including slit based method and quad scan method. An on-line emittance measurement based on multi-slit method is developed so the emittance measured will be immediately available to support further beam optimization. In this report we will present the results from the emittance studies using this tool. We will also present the emittance measurement based on quads scan technique for the high energy beam line.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF025
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THPMF028	Coherent Stacking Scheme for Inverse-Compton Scattering at MHz Repetition Rates	4103
	P. Piot, D. Mihalcea Northern Illinois University, DeKalb, Illinois, USA T.J. Campese, A.Y. Murokh RadiaBeam Systems, Santa Monica, California, USA D. Mihalcea, P. Piot, J. Ruan Fermilab, Batavia, Illinois, USA
	Funding: Work sponsored by the DNDO award 2015-DN-077-ARI094 to Northern Illinois University and US DOE contract DE-AC02-07CH11359 to Fermilab. An experiment to produce 1-MeV gamma rays via Compton back-scattering of infrared photons on 250-MeV electron bunches is currently in preparation at the Fermilab Accelerator Science & Technology (FAST) facility. To increase the gamma-ray flux the energy of the infrared laser pulses are planned to be amplified within the interaction region using a resonant cavity. This passive amplifier composed of a Fabry-Perot cavity will allow the laser pulse bunches to coherently and constructively stack. Our estimates, based on theoretical models, show that the laser pulse energy can be increased from approximately 1-2 mJ at the exit of the last active amplifier to 5 -10 mJ at the interaction point when the laser repetition rate is set at the nominal value of 3 MHz. This paper details the cavity design option(s) and associated wave-optic simulations.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF028
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THPMF048	Bunch Length Measurements Using CTR at the AWA with Comparison to Simulation	4166
	N.R. Neveu IIT, Chicago, Illinois, USA S.P. Antipov Euclid TechLabs, LLC, Solon, Ohio, USA A. Halavanau, P. Piot Northern Illinois University, DeKalb, Illinois, USA P. Piot Fermilab, Batavia, Illinois, USA J.G. Power, C. Whiteford, E.E. Wisniewski ANL, Argonne, Illinois, USA L.K. Spentzouris Illinois Institute of Technology, Chicago, Illinois, USA
	Funding: This work is funded by the DOE Office of Science, grant no. DE-SC0015479, and contract No. DE-AC02- 06CH11357. In this paper we present electron bunch length measurements at the Argonne Wakefield Accelerator (AWA) photoinjector facility. The AWA accelerator has a large dynamic charge density range, with electron beam charge varying between 0.1 nC - 100 nC, and laser spot size diameter at the cathode between 0.1 mm - 18 mm. The bunch length measurements were taken at different charge densities using a metallic screen and a Martin-Puplett interferometer to perform autocorrelation scans of the corresponding coherent transition radiation (CTR). A liquid helium-cooled 4K bolometer was used to register the interferometer signal. The experimental results are compared with Impact-T and OPAL-T numerical simulations.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF048
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THPMK023	Coherent Transition Radiation Generated from Transverse Electron Density Modulation	4348
	A. Halavanau, P. Piot Northern Illinois University, DeKalb, Illinois, USA A.I. Benediktovitch BSU, Minsk, Belarus, Belarus S.N. Galyamin, A.V. Tyukhtin Saint Petersburg State University, Saint Petersburg, Russia P. Piot Fermilab, Batavia, Illinois, USA
	Coherent Transition radiation (CTR) of a given frequency is commonly generated with longitudinal electron bunch trains. In this paper we present a study of CTR production from electron transverse density modulation. We demonstrate via numerical simulations a simple technique to generate THz-scale frequencies from mm-scale transversely separated electron beamlets. The results and a potential experimental setup are discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK023
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Paper

Title

Page

Demonstration of Fast, Single-shot Photocathode QE Mapping Method Using MLA Pattern Beam

1293

E.E. Wisniewski, M.E. Conde, D.S. Doran, W. Gai, Q. Gao, W. Liu, J.G. Power, C. Whiteford
ANL, Argonne, Illinois, USA
Q. Gao
TUB, Beijing, People's Republic of China
G. Ha
PAL, Pohang, Republic of Korea
A. Halavanau, P. Piot
Northern Illinois University, DeKalb, Illinois, USA
P. Piot
Fermilab, Batavia, Illinois, USA

Funding: UChicago Argonne, LLC, Operator of Argonne National Laboratory ("Argonne"). Argonne, a U.S.A. Department of Energy Office of Science laboratory, is operated under Contract No. DE-AC02-06CH11357.
Quantum efficiency (QE) is the chief figure of merit in the characterization of photocathodes. Semiconductor photocathodes, especially when used in high rep-rate photo-injectors, are known to show QE degradation over time and must be replaced. The total QE is the basic diagnostic which is used widely and is easy to obtain. However, a QE map indicating variations of QE across the cathode surface has greater utility. It can quickly diagnose problems of QE inhomogeneity. Most QE mapping techniques require hours to complete and are thus disruptive to a user facility schedule. A fast, single-shot method has been proposed (citation) using a micro-lens array (MLA) generated QE map. In this paper we report the implementation of the method at Argonne Wakefield Accelerator facility. A micro-lens array (MLA) is used to project an array of beamlets onto the photocathode. The resulting photoelectron beam in the form of an array of electron beamlets is imaged at a YAG screen. Four synchronized measurements are made and the results used to produce a QE map of the photocathode.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF020

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THPAK057

Simulations of Optical Stochastic Cooling with ELEGANT

3354

M.B. Andorf, P. Piot
Northern Illinois University, DeKalb, Illinois, USA
V.A. Lebedev, V.A. Lebedev, P. Piot
Fermilab, Batavia, Illinois, USA

Fermilab is pursuing a proof-of-principle test of the Optical Stochastic Cooling (OSC) of 100 MeV electrons in the Integrable Optics Test Accelerator. In support of this we present simulations of horizontal damping with OSC. We find excellent agreement with theory on the amplitude dependent damping rates. Additionally particle tracking is used to confirm the necessity and effectiveness of sextupoles used to correct non-linear path lengthening in the OSC chicane.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK057

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THPAK058

Planned Detection and Amplification of Infared Synchrotron Radiation for Electron-Beam Diagnostics and Manipulations

3358

M.B. Andorf, P. Piot
Northern Illinois University, DeKalb, Illinois, USA
P. Piot
Fermilab, Batavia, Illinois, USA

Amplification of beam-induced radiation (e.g. synchrotron or undulator radiation) is a necessary component of optical stochastic cooling of hadrons or heavy ions. We discuss a proposal to measure and amplify synchrotron radiation from a bending magnet of the Advanced Photon Source. The measurements will be in the short-wavelength infrared region (SWIR) and amplification will be accomplished using a pumped Chromium:Zinc Selenide (Cr:ZnSe) crystal with maximum gain at λ≅ 2.2~μm.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK058

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THPAK060

Transverse-to-Longitudinal Photocathode Distribution Imaging

3361

SUSPF084

use link to see paper's listing under its alternate paper code

A. Halavanau, P. Piot
Northern Illinois University, DeKalb, Illinois, USA
W. Gai, G. Ha, J.G. Power, E.E. Wisniewski
ANL, Argonne, Illinois, USA
G. Ha
PAL, Pohang, Republic of Korea
P. Piot
Fermilab, Batavia, Illinois, USA
G. Qiang
TUB, Beijing, People's Republic of China

In this paper, we present a tunable picosecond-scale bunch train generation technique combining a microlens array (MLA) transverse laser shaper and a transverse-to-longitudinal emittance exchange (EEX) beamline. The modulated beamlet array is formed at the photocathode with the MLA setup. The resulting patterned electron beam is accelerated to 50 MeV and transported to the entrance of the EEX setup. A quadrupole channel is used to adjust the transverse spacing of the beamlet array upstream of the EEX, thereby enabling the generation of a bunch train with tunable separation downstream of the EEX beamline. Additionally, the MLA is mounted on a rotation stage which provides additional flexibility to produce high-frequency beam density modulation downstream of the EEX. Experimental results obtained at the Argonne Wakefield Accelerator (AWA) facility are presented and compared with numerical simulations.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK060

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THPAK061

Magnetized and Flat Beam Generation at the Fermilab's FAST Facility

3364

A. Halavanau, P. Piot
Northern Illinois University, DeKalb, Illinois, USA
D.J. Crawford, D.R. Edstrom, D. Mihalcea, S. Nagaitsev, P. Piot, A.L. Romanov, J. Ruan, V.D. Shiltsev
Fermilab, Batavia, Illinois, USA

Funding: This work is supported by the DOE contract No.DEAC02-07CH11359 to the Fermi Research Alliance LLC. A.H. is supported by the DOE under contract No. DE-SC0011831 with Northern Illinois University.
Canonical angular momentum (CAM) dominated beams can be formed in photoinjectors by applying an axial magnetic field on the photocathode surface. Such a beam possess asymmetric eigenemittances and is characterized by the measure of its magnetization. CAM removal using a set skew-quadrupole magnets maps the beam eigenemittances to the conventional emittance along each transverse degree of freedom thereby yielding flat beam with asymmetric transverse emittance. In this paper we report on the experimental generation of CAM dominated beam and their subsequent transformation into flat beams at the Fermilab Accelerator Science and Technology (FAST) facility. Our results are compared with numerical simulations and possible applications of the produced beams are discussed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK061

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THPAK062

Bunch Compression of Flat Beams

3368

A. Halavanau, P. Piot
Northern Illinois University, DeKalb, Illinois, USA
D.J. Crawford, D.R. Edstrom, D. Mihalcea, S. Nagaitsev, P. Piot, A.L. Romanov, J. Ruan, V.D. Shiltsev
Fermilab, Batavia, Illinois, USA

Funding: This work is supported by the DOE contract No.DEAC02-07CH11359 to the Fermi Research Alliance LLC. A.H. is supported by the DOE under contract No. DE-SC0011831 with Northern Illinois University.
Flat beams can be produced via a linear manipulation of canonical angular momentum (CAM) dominated beams using a set of skew-quadrupole magnets. Recently such beams were produced at Fermilab Accelerator Science and Technology (FAST) facility. In this paper, we report the results of flat beam compression study in a magnetic chicane at an energy of E~32 MeV. Additionally, we investigate the effect of energy chirp in the round-to-flat beam transform. The experimental results are compared with numerical simulations.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK062

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THPAK063

Electron Beam Pattern Rotation as a Method of Tunable Bunch Train Generation

3372

A. Halavanau, P. Piot
Northern Illinois University, DeKalb, Illinois, USA
P. Piot
Fermilab, Batavia, Illinois, USA

Transversely modulated electron beams can be formed in photo injectors via microlens array (MLA) UV laser shaping technique. Micro lenses can be arranged in polygonal lattices, with resulting transverse electron beam modulation mimicking the lenses pattern. Conventionally, square MLAs are used for UV laser beam shaping, and generated electron beam patterns form square beamlet arrays. The MLA setup can be placed on a rotational mount, thereby rotating electron beam distribution. In combination with transverse-to-longitudinal emittance exchange beam line, it allows to vary beamlets horizontal projection and tune electron bunch train. In this paper, we extend the technique to the case of different MLA lattice arrangements and explore the benefits of its rotational symmetries.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK063

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

THPAK065

Application of Transverse-to-Longitudinal Phase-Space-Exchanged Beam Produced from a Nano-Structure Photocathode to a Soft X-Ray Free-Electron Laser

3379

SUSPF085

use link to see paper's listing under its alternate paper code

A. Lueangaramwong, P. Piot
Northern Illinois University, DeKalb, Illinois, USA
G. Andonian
RadiaBeam, Santa Monica, California, USA
P. Piot
Fermilab, Batavia, Illinois, USA

Nano-structured cathodes can form transversely modulated beams which can be subsequently converted to temporally modulated beam via a transverse-to-longitudinal phase space-exchanging beamline. We demonstrate via numerical simulation the generation of transversely modulated beam at the nm scale and investigate the corresponding enhancement in a soft-X-ray SASE free-electron laser. Our study is supported by start-to-end simulation combining WARP, IMPACT-T and GENESIS(FEL process) and focuses on the optimization of the beamline to preserve initial modulation at the nanometer level. We also discuss the scaling of the concept to shorter-wavelengths.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK065

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THPMF025

Emittance Measurements at FAST Facility

4100

J. Ruan, D.R. Broemmelsiek, D.J. Crawford, A.L. Edelen, J.P. Edelen, D.R. Edstrom, A.H. Lumpkin, P. Piot, A.L. Romanov, R.M. Thurman-Keup
Fermilab, Batavia, Illinois, USA
P. Piot
Northern Illinois University, DeKalb, Illinois, USA

Funding: *Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy.
The FAST facility at Fermilab recently been commissioned has demonstrated the generation of electron beam within a wide range of parameter (energy, charge) suitable for accelerator-science and beam-physics experiments. This accelerator consists of a photo-electron gun, injector, ILC-type cryomodules, and multiple downstream beam-lines. It will mainly serve as injector for the upcoming Integrable Optical Test Accelerator (IOTA). At the same time we will also carry out a LINAC based intense gamma ray experiment based on the Inverse Compton scattering. It is essential to understand the beam emittance for both experiments. A number of techniques are used to characaterizing the beam emittance including slit based method and quad scan method. An on-line emittance measurement based on multi-slit method is developed so the emittance measured will be immediately available to support further beam optimization. In this report we will present the results from the emittance studies using this tool. We will also present the emittance measurement based on quads scan technique for the high energy beam line.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF025

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THPMF028

Coherent Stacking Scheme for Inverse-Compton Scattering at MHz Repetition Rates

4103

P. Piot, D. Mihalcea
Northern Illinois University, DeKalb, Illinois, USA
T.J. Campese, A.Y. Murokh
RadiaBeam Systems, Santa Monica, California, USA
D. Mihalcea, P. Piot, J. Ruan
Fermilab, Batavia, Illinois, USA

Funding: Work sponsored by the DNDO award 2015-DN-077-ARI094 to Northern Illinois University and US DOE contract DE-AC02-07CH11359 to Fermilab.
An experiment to produce 1-MeV gamma rays via Compton back-scattering of infrared photons on 250-MeV electron bunches is currently in preparation at the Fermilab Accelerator Science & Technology (FAST) facility. To increase the gamma-ray flux the energy of the infrared laser pulses are planned to be amplified within the interaction region using a resonant cavity. This passive amplifier composed of a Fabry-Perot cavity will allow the laser pulse bunches to coherently and constructively stack. Our estimates, based on theoretical models, show that the laser pulse energy can be increased from approximately 1-2 mJ at the exit of the last active amplifier to 5 -10 mJ at the interaction point when the laser repetition rate is set at the nominal value of 3 MHz. This paper details the cavity design option(s) and associated wave-optic simulations.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF028

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THPMF048

Bunch Length Measurements Using CTR at the AWA with Comparison to Simulation

4166

N.R. Neveu
IIT, Chicago, Illinois, USA
S.P. Antipov
Euclid TechLabs, LLC, Solon, Ohio, USA
A. Halavanau, P. Piot
Northern Illinois University, DeKalb, Illinois, USA
P. Piot
Fermilab, Batavia, Illinois, USA
J.G. Power, C. Whiteford, E.E. Wisniewski
ANL, Argonne, Illinois, USA
L.K. Spentzouris
Illinois Institute of Technology, Chicago, Illinois, USA

Funding: This work is funded by the DOE Office of Science, grant no. DE-SC0015479, and contract No. DE-AC02- 06CH11357.
In this paper we present electron bunch length measurements at the Argonne Wakefield Accelerator (AWA) photoinjector facility. The AWA accelerator has a large dynamic charge density range, with electron beam charge varying between 0.1 nC - 100 nC, and laser spot size diameter at the cathode between 0.1 mm - 18 mm. The bunch length measurements were taken at different charge densities using a metallic screen and a Martin-Puplett interferometer to perform autocorrelation scans of the corresponding coherent transition radiation (CTR). A liquid helium-cooled 4K bolometer was used to register the interferometer signal. The experimental results are compared with Impact-T and OPAL-T numerical simulations.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF048

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THPMK023

Coherent Transition Radiation Generated from Transverse Electron Density Modulation

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A. Halavanau, P. Piot
Northern Illinois University, DeKalb, Illinois, USA
A.I. Benediktovitch
BSU, Minsk, Belarus, Belarus
S.N. Galyamin, A.V. Tyukhtin
Saint Petersburg State University, Saint Petersburg, Russia
P. Piot
Fermilab, Batavia, Illinois, USA

Coherent Transition radiation (CTR) of a given frequency is commonly generated with longitudinal electron bunch trains. In this paper we present a study of CTR production from electron transverse density modulation. We demonstrate via numerical simulations a simple technique to generate THz-scale frequencies from mm-scale transversely separated electron beamlets. The results and a potential experimental setup are discussed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK023

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