IPAC2015 - List of Authors (Ha, G.)

Paper	Title	Page
MOPJE019	Categorization and Estimation of Possible Deformation in Emittance Exchange based Current Profile Shaping	317
	G. Ha, M.-H. Cho, W. Namkung POSTECH, Pohang, Kyungbuk, Republic of Korea W. Gai, G. Ha, K.-J. Kim, J.G. Power ANL, Argonne, Illinois, USA
	Funding: This work is partly supported by POSTECH BK²¹⁺ program and Argonne National Laboratory Shaping the current profile is one of the important issues in collinear wakefield acceleration. In the emittance exchange based shaping technique, the shaped current profile seriously depends on the incoming beam and beam line parameters. To design the beam and beam line properly, it is important to estimate the deformation in the shaped current profile. There are several different deformation types whose level depend on deformation parameter. We categorize the possible deformation types and observe the deformation patterns of the current profile depending on its type and the deformation parameter.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPJE019
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MOPJE020	High Resolution Longitudinal Property Measurement using Emittance Exchange Beam Line	320
	G. Ha, M.-H. Cho, W. Namkung POSTECH, Pohang, Kyungbuk, Republic of Korea W. Gai, G. Ha, K.-J. Kim, J.G. Power ANL, Argonne, Illinois, USA
	Most of longitudinal measurement techniques introduce the transverse-longitudinal correlation because it is very hard to measure the longitudinal properties directly. This correlation is necessary to observe the longitudinal property through the transverse screen, but initial transverse components of the beam restrict the measurement. It is possible to overcome this intrinsic limit using emittance exchange beam line which makes transverse properties at the downstream only depend on longitudinal properties at the upstream. We present the new idea to measure the longitudinal properties using the emittance exchange beam line and preliminary simulation results.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPJE020
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MOPWI015	A Low Time-Dispersion Refractive Optical Transmission Line for Streak Camera Measurements	1178
	J.G. Power, G. Ha ANL, Argonne, Illinois, USA G. Ha POSTECH, Pohang, Kyungbuk, Republic of Korea
	Funding: Work supported by the U.S. Department of Energy office of High Energy Physics. Streak camera measurements of the charge particle bunch length are limited in resolution due to several factors: (1) the light from the source (optical transition radiation, Cherenkov, synchrotron radiation, etc.); (2) time dispersion introduced in the optical transmission line between the source and the streak camera; and finally (3) the streak camera resolution. The limiting resolution usually arises from the optical transmission line. While an all-reflective transmission line can eliminate dispersion, the system is complicated and expensive. In this paper, we consider how to design a refractive optical transport line to minimize the time dispersion while maximizing the signal. We present a theoretical model of the dispersion, modeling, and measurements of the time dispersion for several different lens materials.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPWI015
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WEAD1	Commissioning and Recent Experimental Results at the Argonne Wakefield Accelerator Facility (AWA)	2472
	M.E. Conde, D.S. Doran, W. Gai, G. Ha, W. Liu, J.G. Power, J.H. Shao, D. Wang, C. Whiteford, E.E. Wisniewski ANL, Argonne, Illinois, USA S.P. Antipov, C.-J. Jing, J.Q. Qiu Euclid TechLabs, LLC, Solon, Ohio, USA G. Ha POSTECH, Pohang, Kyungbuk, Republic of Korea J.H. Shao, D. Wang TUB, Beijing, People's Republic of China
	Funding: Work supported by the U.S. Department of Energy under contract No. DE-AC02-06CH11357. The commissioning of the upgraded AWA facility has been recently completed. The L-band electron gun has been fully commissioned and has been successfully operated with its Cesium Telluride photocathode at a gradient of 80 MV/m. Single bunches of up to 100 nC, and bunch trains of up to 32 bunches have been generated. The six new pi-mode accelerating cavities bring the beam energy to 75 MeV. Initial measurements of the beam parameters have been performed. This intense beam has been used to drive high gradient wakefields in several structures. A second beamline provides electron bunches to probe the wakefields generated by the intense drive beam. One of the main goals of the facility is to generate short RF pulses with GW power levels, corresponding to accelerating gradients of hundreds of MV/m and energy gains on the order of 100 MeV per structure.
	Slides WEAD1 [2.091 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEAD1
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WEPWA034	High-charge-short-bunch Operation Possibility at Argonne Wakefield Accelerator Facility	2572
	G. Ha, M.-H. Cho, W. Namkung POSTECH, Pohang, Kyungbuk, Republic of Korea W. Gai, G. Ha, K.-J. Kim, J.G. Power ANL, Argonne, Illinois, USA
	Originally the drive beam line at Argonne Wakefield Accelerator (AWA) Facility was designed to generate the high charge bunch train. However, we recently installed the double dog-leg type emittance exchange beam line which have two identical dog-leg structures. With this beam line, it is possible to compress the bunch by introducing the chicane or using single dog-leg. Simulation studies have been carried out to confirm the minimum bunch length for each charge and the emittance growth by the coherent synchrotron radiation. We present GPT simulation results to show high-charge-short-bunch operation possibility at AWA facility.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA034
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WEPWA035	Initial EEX-based Bunch Shaping Experiment Results at the Argonne Wakefield Accelerator Facility	2575
	G. Ha, M.-H. Cho, W. Namkung POSTECH, Pohang, Kyungbuk, Republic of Korea M.E. Conde, D.S. Doran, W. Gai, G. Ha, C.-J. Jing, K.-J. Kim, W. Liu, J.G. Power, Y.-E. Sun, C. Whiteford, E.E. Wisniewski, A. Zholents ANL, Argonne, Illinois, USA C.-J. Jing Euclid TechLabs, LLC, Solon, Ohio, USA P. Piot Fermilab, Batavia, Illinois, USA
	Funding: This work is partly supported by POSTECH BK²¹⁺ and Argonne National Laboratory A program is under development at Argonne National Laboratory to use an emittance exchange (EEX) beamline to perform longitudinal bunch shaping (LBS). The double dog-leg EEX beamline was recently installed at the Argonne Wakefield Accelerator (AWA) and the goals of the proof-of-principle experiment are to demonstrate LBS and characterize its deformations from the ideal shape due to higher-order and collective effects. The LBS beamline at the AWA consists of insert-able transverse masks mounted on an actuator and four quadrupoles (to manipulate the transverse phase space) before the EEX beamline, which consists of two identical dog-legs and a deflecting cavity. The mask and input beam parameters are varied during the experiment to explore the shaping capability and clarify the deformation sources and their mitigation. Progress on the commissioning of the LBS beamline, initial experimental data and benchmarks to GPT simulations will be presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA035
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WEPJE008	Experimental Study of Wakefields in an X-band Photonic Band Gap Accelerating Structure	2689
	E.I. Simakov, S. Arsenyev, C.E. Buechler, R.L. Edwards, W.P. Romero LANL, Los Alamos, New Mexico, USA M.E. Conde, G. Ha, C.-J. Jing, J.G. Power, E.E. Wisniewski ANL, Argonne, Illinois, USA C.-J. Jing Euclid TechLabs, LLC, Solon, Ohio, USA
	Funding: This work is supported by U.S. Department of Energy (DOE) Office of Science Early Career Research Program. We designed an experiment to conduct a detailed investigation of higher order mode spectrum in a room-temperature traveling-wave photonic band gap (PBG) accelerating structure at 11.7 GHz. It has been long recognized that PBG structures have great potential in reducing long-range wakefields in accelerators. The first ever demonstration of acceleration in room-temperature PBG structures was conducted at MIT in 2005. Since then, the importance of that device has been recognized by many research institutions. However, the full experimental characterization of the wakefield spectrum in a beam test has not been performed to date. The Argonne Wakefield Accelerator (AWA) test facility at the Argonne National Laboratory represents a perfect site where this evaluation could be conducted with a single high charge electron bunch and with a train of bunches. Here we describe fabrication and tuning of PBG cells, the final cold-test of the traveling-wave accelerating structure, and the results of the beam testing at AWA.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPJE008
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WEPJE020	The Two Beam Acceleration Staging Experiment at Argonne Wakefield Accelerator Facility	2714
	C.-J. Jing, S.P. Antipov, A. Kanareykin, J.Q. Qiu Euclid TechLabs, LLC, Solon, Ohio, USA M.E. Conde, D.S. Doran, W. Gai, G. Ha, W. Liu, J.G. Power, J.H. Shao, D. Wang, E.E. Wisniewski ANL, Argonne, Illinois, USA J. Shi TUB, Beijing, People's Republic of China
	Funding: DoE SBIR Program Staging, defined as the accelerated bunch in a wakefield accelerator continues to gain energy from sequential drive bunches, is one of the most critical technologies, yet be demonstrated, required to achieve high energy. Using the Two Beam Acceleration (TBA) beamline at Argonne Wakefield Accelerator facility, we will perform a staging experiment using two X-band TBA units. The experiment is planned to conduct in steps. We report on the most recent progress.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPJE020
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WEPMN017	High Power RF Radiation at W-band Based on Wakefields Excited by Intense Electron Beam	2960
	D. Wang, C.-X. Tang TUB, Beijing, People's Republic of China S.P. Antipov, C.-J. Jing, J.Q. Qiu Euclid TechLabs, LLC, Solon, Ohio, USA M.E. Conde, D.S. Doran, W. Gai, G. Ha, W. Liu, J.G. Power, E.E. Wisniewski ANL, Argonne, Illinois, USA
	We report the experiment design and preliminary results on high power RF generation at W-band based on coherent wakefields from the metallic periodic structure of 91 GHz PETS (power extraction and transfer structure), excited by intense electron beam at the Argonne Wakefield Accelerator (AWA) facility. The recently output RF power is 0.7 MW, with 67 MeV, 1.4 nC single electron beam going through the structure. The RF pulse length is 3.4 ns. We measure the energy loss of electron beam as reference to the RF generation, which agrees well with the simulation results. Next run is to increase the output RF power with higher charge and to excite coherent wakefields with electron bunch train. The output RF peak power is expected to be ~100 MW and the electrical field gradient can reach up to 400 MV/m, with RF pulse duration adjustable from few ns to 30 ns when excited with 5~10 nC charge in a single bunch and up to 32 sub bunches in total.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMN017
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WEPTY012	Multiple Scattering Effects of a Thin Beryllium Window on a Short, 2 nC, 60 MeV Bunched Electron Beam	3280
	E.E. Wisniewski, M.E. Conde, W. Gai, G. Ha, J.G. Power ANL, Argonne, Illinois, USA G. Ha POSTECH, Pohang, Kyungbuk, Republic of Korea
	Funding: U.S. Dept of Energy Office of Science under contract number DE-AC02-06CH11357. The Argonne Wakefield Accelerator 75 MeV drive beamline at Argonne National Laboratory has as its electron source a Cesium telluride photocathode gun with a vacuum requirement on the order of 10^-10 torr. In conflict with this, the experimental program at AWA sometimes requires beamline installation of experimental structures which due to materials and/or construction cannot meet the stringent vacuum requirement. One solution is to sequester these types of structures inside a separate vacuum chamber and inject the beam through a thin Beryllium window. The downside is that multiple scattering effects degrade the beam quality to some degree which is not well-known. This study was done in an effort to better understand and predict the multiple scattering effects of the Be thin window, particularly on the beam transverse size. The results of measurements are compared with GEANT4 Monte Carlo simulations via G4beamline and analytical calculations via GPT.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPTY012
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Paper

Title

Page

Categorization and Estimation of Possible Deformation in Emittance Exchange based Current Profile Shaping

317

G. Ha, M.-H. Cho, W. Namkung
POSTECH, Pohang, Kyungbuk, Republic of Korea
W. Gai, G. Ha, K.-J. Kim, J.G. Power
ANL, Argonne, Illinois, USA

Funding: This work is partly supported by POSTECH BK²¹⁺ program and Argonne National Laboratory
Shaping the current profile is one of the important issues in collinear wakefield acceleration. In the emittance exchange based shaping technique, the shaped current profile seriously depends on the incoming beam and beam line parameters. To design the beam and beam line properly, it is important to estimate the deformation in the shaped current profile. There are several different deformation types whose level depend on deformation parameter. We categorize the possible deformation types and observe the deformation patterns of the current profile depending on its type and the deformation parameter.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPJE019

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MOPJE020

High Resolution Longitudinal Property Measurement using Emittance Exchange Beam Line

320

G. Ha, M.-H. Cho, W. Namkung
POSTECH, Pohang, Kyungbuk, Republic of Korea
W. Gai, G. Ha, K.-J. Kim, J.G. Power
ANL, Argonne, Illinois, USA

Most of longitudinal measurement techniques introduce the transverse-longitudinal correlation because it is very hard to measure the longitudinal properties directly. This correlation is necessary to observe the longitudinal property through the transverse screen, but initial transverse components of the beam restrict the measurement. It is possible to overcome this intrinsic limit using emittance exchange beam line which makes transverse properties at the downstream only depend on longitudinal properties at the upstream. We present the new idea to measure the longitudinal properties using the emittance exchange beam line and preliminary simulation results.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPJE020

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MOPWI015

A Low Time-Dispersion Refractive Optical Transmission Line for Streak Camera Measurements

1178

J.G. Power, G. Ha
ANL, Argonne, Illinois, USA
G. Ha
POSTECH, Pohang, Kyungbuk, Republic of Korea

Funding: Work supported by the U.S. Department of Energy office of High Energy Physics.
Streak camera measurements of the charge particle bunch length are limited in resolution due to several factors: (1) the light from the source (optical transition radiation, Cherenkov, synchrotron radiation, etc.); (2) time dispersion introduced in the optical transmission line between the source and the streak camera; and finally (3) the streak camera resolution. The limiting resolution usually arises from the optical transmission line. While an all-reflective transmission line can eliminate dispersion, the system is complicated and expensive. In this paper, we consider how to design a refractive optical transport line to minimize the time dispersion while maximizing the signal. We present a theoretical model of the dispersion, modeling, and measurements of the time dispersion for several different lens materials.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPWI015

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WEAD1

Commissioning and Recent Experimental Results at the Argonne Wakefield Accelerator Facility (AWA)

2472

M.E. Conde, D.S. Doran, W. Gai, G. Ha, W. Liu, J.G. Power, J.H. Shao, D. Wang, C. Whiteford, E.E. Wisniewski
ANL, Argonne, Illinois, USA
S.P. Antipov, C.-J. Jing, J.Q. Qiu
Euclid TechLabs, LLC, Solon, Ohio, USA
G. Ha
POSTECH, Pohang, Kyungbuk, Republic of Korea
J.H. Shao, D. Wang
TUB, Beijing, People's Republic of China

Funding: Work supported by the U.S. Department of Energy under contract No. DE-AC02-06CH11357.
The commissioning of the upgraded AWA facility has been recently completed. The L-band electron gun has been fully commissioned and has been successfully operated with its Cesium Telluride photocathode at a gradient of 80 MV/m. Single bunches of up to 100 nC, and bunch trains of up to 32 bunches have been generated. The six new pi-mode accelerating cavities bring the beam energy to 75 MeV. Initial measurements of the beam parameters have been performed. This intense beam has been used to drive high gradient wakefields in several structures. A second beamline provides electron bunches to probe the wakefields generated by the intense drive beam. One of the main goals of the facility is to generate short RF pulses with GW power levels, corresponding to accelerating gradients of hundreds of MV/m and energy gains on the order of 100 MeV per structure.

Slides WEAD1 [2.091 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEAD1

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WEPWA034

High-charge-short-bunch Operation Possibility at Argonne Wakefield Accelerator Facility

2572

G. Ha, M.-H. Cho, W. Namkung
POSTECH, Pohang, Kyungbuk, Republic of Korea
W. Gai, G. Ha, K.-J. Kim, J.G. Power
ANL, Argonne, Illinois, USA

Originally the drive beam line at Argonne Wakefield Accelerator (AWA) Facility was designed to generate the high charge bunch train. However, we recently installed the double dog-leg type emittance exchange beam line which have two identical dog-leg structures. With this beam line, it is possible to compress the bunch by introducing the chicane or using single dog-leg. Simulation studies have been carried out to confirm the minimum bunch length for each charge and the emittance growth by the coherent synchrotron radiation. We present GPT simulation results to show high-charge-short-bunch operation possibility at AWA facility.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA034

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WEPWA035

Initial EEX-based Bunch Shaping Experiment Results at the Argonne Wakefield Accelerator Facility

2575

G. Ha, M.-H. Cho, W. Namkung
POSTECH, Pohang, Kyungbuk, Republic of Korea
M.E. Conde, D.S. Doran, W. Gai, G. Ha, C.-J. Jing, K.-J. Kim, W. Liu, J.G. Power, Y.-E. Sun, C. Whiteford, E.E. Wisniewski, A. Zholents
ANL, Argonne, Illinois, USA
C.-J. Jing
Euclid TechLabs, LLC, Solon, Ohio, USA
P. Piot
Fermilab, Batavia, Illinois, USA

Funding: This work is partly supported by POSTECH BK²¹⁺ and Argonne National Laboratory
A program is under development at Argonne National Laboratory to use an emittance exchange (EEX) beamline to perform longitudinal bunch shaping (LBS). The double dog-leg EEX beamline was recently installed at the Argonne Wakefield Accelerator (AWA) and the goals of the proof-of-principle experiment are to demonstrate LBS and characterize its deformations from the ideal shape due to higher-order and collective effects. The LBS beamline at the AWA consists of insert-able transverse masks mounted on an actuator and four quadrupoles (to manipulate the transverse phase space) before the EEX beamline, which consists of two identical dog-legs and a deflecting cavity. The mask and input beam parameters are varied during the experiment to explore the shaping capability and clarify the deformation sources and their mitigation. Progress on the commissioning of the LBS beamline, initial experimental data and benchmarks to GPT simulations will be presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA035

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WEPJE008

Experimental Study of Wakefields in an X-band Photonic Band Gap Accelerating Structure

2689

E.I. Simakov, S. Arsenyev, C.E. Buechler, R.L. Edwards, W.P. Romero
LANL, Los Alamos, New Mexico, USA
M.E. Conde, G. Ha, C.-J. Jing, J.G. Power, E.E. Wisniewski
ANL, Argonne, Illinois, USA
C.-J. Jing
Euclid TechLabs, LLC, Solon, Ohio, USA

Funding: This work is supported by U.S. Department of Energy (DOE) Office of Science Early Career Research Program.
We designed an experiment to conduct a detailed investigation of higher order mode spectrum in a room-temperature traveling-wave photonic band gap (PBG) accelerating structure at 11.7 GHz. It has been long recognized that PBG structures have great potential in reducing long-range wakefields in accelerators. The first ever demonstration of acceleration in room-temperature PBG structures was conducted at MIT in 2005. Since then, the importance of that device has been recognized by many research institutions. However, the full experimental characterization of the wakefield spectrum in a beam test has not been performed to date. The Argonne Wakefield Accelerator (AWA) test facility at the Argonne National Laboratory represents a perfect site where this evaluation could be conducted with a single high charge electron bunch and with a train of bunches. Here we describe fabrication and tuning of PBG cells, the final cold-test of the traveling-wave accelerating structure, and the results of the beam testing at AWA.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPJE008

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WEPJE020

The Two Beam Acceleration Staging Experiment at Argonne Wakefield Accelerator Facility

2714

C.-J. Jing, S.P. Antipov, A. Kanareykin, J.Q. Qiu
Euclid TechLabs, LLC, Solon, Ohio, USA
M.E. Conde, D.S. Doran, W. Gai, G. Ha, W. Liu, J.G. Power, J.H. Shao, D. Wang, E.E. Wisniewski
ANL, Argonne, Illinois, USA
J. Shi
TUB, Beijing, People's Republic of China

Funding: DoE SBIR Program
Staging, defined as the accelerated bunch in a wakefield accelerator continues to gain energy from sequential drive bunches, is one of the most critical technologies, yet be demonstrated, required to achieve high energy. Using the Two Beam Acceleration (TBA) beamline at Argonne Wakefield Accelerator facility, we will perform a staging experiment using two X-band TBA units. The experiment is planned to conduct in steps. We report on the most recent progress.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPJE020

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WEPMN017

High Power RF Radiation at W-band Based on Wakefields Excited by Intense Electron Beam

2960

D. Wang, C.-X. Tang
TUB, Beijing, People's Republic of China
S.P. Antipov, C.-J. Jing, J.Q. Qiu
Euclid TechLabs, LLC, Solon, Ohio, USA
M.E. Conde, D.S. Doran, W. Gai, G. Ha, W. Liu, J.G. Power, E.E. Wisniewski
ANL, Argonne, Illinois, USA

We report the experiment design and preliminary results on high power RF generation at W-band based on coherent wakefields from the metallic periodic structure of 91 GHz PETS (power extraction and transfer structure), excited by intense electron beam at the Argonne Wakefield Accelerator (AWA) facility. The recently output RF power is 0.7 MW, with 67 MeV, 1.4 nC single electron beam going through the structure. The RF pulse length is 3.4 ns. We measure the energy loss of electron beam as reference to the RF generation, which agrees well with the simulation results. Next run is to increase the output RF power with higher charge and to excite coherent wakefields with electron bunch train. The output RF peak power is expected to be ~100 MW and the electrical field gradient can reach up to 400 MV/m, with RF pulse duration adjustable from few ns to 30 ns when excited with 5~10 nC charge in a single bunch and up to 32 sub bunches in total.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMN017

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WEPTY012

Multiple Scattering Effects of a Thin Beryllium Window on a Short, 2 nC, 60 MeV Bunched Electron Beam

3280

E.E. Wisniewski, M.E. Conde, W. Gai, G. Ha, J.G. Power
ANL, Argonne, Illinois, USA
G. Ha
POSTECH, Pohang, Kyungbuk, Republic of Korea

Funding: U.S. Dept of Energy Office of Science under contract number DE-AC02-06CH11357.
The Argonne Wakefield Accelerator 75 MeV drive beamline at Argonne National Laboratory has as its electron source a Cesium telluride photocathode gun with a vacuum requirement on the order of 10^-10 torr. In conflict with this, the experimental program at AWA sometimes requires beamline installation of experimental structures which due to materials and/or construction cannot meet the stringent vacuum requirement. One solution is to sequester these types of structures inside a separate vacuum chamber and inject the beam through a thin Beryllium window. The downside is that multiple scattering effects degrade the beam quality to some degree which is not well-known. This study was done in an effort to better understand and predict the multiple scattering effects of the Be thin window, particularly on the beam transverse size. The results of measurements are compared with GEANT4 Monte Carlo simulations via G4beamline and analytical calculations via GPT.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPTY012

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