IPAC2012 - List of Authors (Yusof, Z.M.)

Paper	Title	Page
MOPPR068	Design and Development of the Diagnostic System for 75 MeV Electron Drive Beam for the AWA Upgrade	942
	J.G. Power, S.P. Antipov, M.E. Conde, W. Gai, C.-J. Jing, W. Liu, E.E. Wisniewski, Z.M. Yusof ANL, Argonne, USA
	Funding: Work supported by High Energy Physics, Office of Science, US DOE We report on the development of the diagnostic system for the ongoing upgrade to the Argonne Wakefield Accelerator (AWA) facility where the electron drive beam energy will be increased from 15 to 75 MeV. The facility will produce a wide dynamic range of drive bunch train formats ranging from a single microbunch of 100 pC to bunch trains of up to 32 bunches spaced by 769 ps with up to 100 nC per bunch. In addition to standard diagnostics, this drive bunch train format poses two challenges for the diagnostic system: (i) the close spacing of the drive bunches, 769 ps, makes resolving the individual pulses difficult and (ii) the dynamic range of the bunch charge varies by x1000. A critical parameter of the drive bunch train for the wakefield accelerator is the charge along the train. To measure this, we are planning to use a 15 GHz digital oscilloscope to read either a BPM or Bergoz FCT. To handle the large dynamic range of charge, the imaging system will make use of GigE Vision cameras and a distributed system of motorized lenses, with remote control of focus, zoom, and aperture, which are operated through terminal servers and RS232 controllers.

TUPPD070	Kelvin Probe Studies of a Cesium Telluride Photocathode for the AWA Photoinjector	1566
	E.E. Wisniewski, K.C. Harkay, Z.M. Yusof ANL, Argonne, USA L.K. Spentzouris, J. Terry, D.G. Velazquez, E.E. Wisniewski Illinois Institute of Technology, Chicago, Illinois, USA
	Cesium telluride is an important photocathode as an electron source for particle accelerators. It has a relatively high quantum efficiency (>1%), is sufficiently robust in a photoinjector, and has a long lifetime. This photocathode is grown in-house for the new Argonne Wakefield Accelerator (AWA) to produce high charge per bunch (~50 nC). Here, we present a study of the "work function" of a cesium telluride photocathode using the Kelvin Probe technique. The study includes an investigation of the correlation between the quantum efficiency and the work function, the effect of photocathode aging, the surprising effect of UV exposure on the work function, and the puzzling behavior of the work function during and after photocathode rejuvenation via heating.

TUPPD071	Development of Cesium Telluride Photocathodes for the AWA Accelerator Upgrade	1569
	Z.M. Yusof, M.E. Conde, W. Gai ANL, Argonne, USA L.K. Spentzouris, E.E. Wisniewski Illinois Institute of Technology, Chicago, Illinois, USA
	Funding: U.S. Department of Energy Office of Science under Contract No. DE-AC02-06CH11357. Cesium telluride photocathodes have been fabricated for the Argonne Wakefield Accelerator (AWA) upgrade. The as-deposited photocathodes have consistently produced quantum efficiency values better than 10% with 254 nm light source and with variation of less than 5% over a circular area of 1.2 inches in diameter. We present various characterizations of the photocathode that have performed, including rejuvenation, lifetime, and performance in the L-band AWA photoinjector.

WEPPP025	A Test-bed for Future Linear Collider Technology: Argonne Wakefield Accelerator Facility (AWA)	2778
	M.E. Conde, D.S. Doran, W. Gai, R. Konecny, W. Liu, J.G. Power, Z.M. Yusof ANL, Argonne, USA S.P. Antipov, C.-J. Jing Euclid TechLabs, LLC, Solon, Ohio, USA E.E. Wisniewski Illinois Institute of Technology, Chicago, Illinois, USA
	Funding: Work supported by the U.S. Department of Energy under contract No. DE-AC02-06CH11357. Research at the AWA Facility has been focused on the development of electron beam driven wakefield structures. Accelerating gradients of up to 100 MV/m have been excited in dielectric loaded cylindrical structures operating in the microwave range of frequencies. Several upgrades, presently underway, will enable the facility to explore higher accelerating gradients, and also be able to generate longer RF pulses of higher intensity. The upgraded 75 MeV drive beam will consist of bunch trains of up to 32 bunches spaced by 0.77 ns with up to 100 nC per bunch. The RF pulses generated by the drive bunches are expected to reach GW power levels, establishing accelerating gradients of hundreds of MV/m.

WEPPD077	Generation of Picosecond Electron-bunch Trains with Variable Spacing Using a Multi-pulse Photocathode Laser	2705
	P. Piot Fermilab, Batavia, USA M.E. Conde, W. Gai, C.-J. Jing, R. Konecny, W. Liu, J.G. Power, Z.M. Yusof ANL, Argonne, USA D. Mihalcea, P. Piot, M.M. Rihaoui Northern Illinois University, DeKalb, Illinois, USA
	Funding: Work supported by DOE awards FG-02-08ER41532 and DE-AC02-06CH11357. We demonstrate the generation of a train of electron bunches with variable spacing at the Argonne Wakefield Accelerator. The photocathode ultraviolet laser pulse consists of a train of four pulses produced via polarization splitting using two alpha-BBO crystals. The photoemitted electron bunches are then manipulated in a horizontally-bending dogleg with variable longitudinal dispersion. A downstream vertically-deflecting cavity is then used to diagnose the temporal profile of the electron beam. The generation of a train composed of four bunches with tunable spacing is demonstrated. Such train of bunch could have application to, e.g., the resonant excitation of wakefield in dielectric-lined waveguides.

WEPPP041	Wakefield Breakdown Test of a Diamond-loaded Accelerating Structure at the AWA	2813
	S.P. Antipov, J.E. Butler, C.-J. Jing, A. Kanareykin, P. Schoessow, S.S. Zuo Euclid TechLabs, LLC, Solon, Ohio, USA S. Baryshev, M.E. Conde, D.S. Doran, W. Gai, R. Konecny, J.G. Power, Z.M. Yusof ANL, Argonne, USA
	Funding: DOE SBIR Diamond has been proposed as a dielectric material for dielectric loaded accelerating (DLA) structures. It has a very low microwave loss tangent, the highest available thermoconductive coefficient and high RF breakdown field. In this paper we report results from a wakefield breakdown test of diamond-loaded rectangular accelerating structure. The high charge beam from the AWA linac (~70 nC, σz = 2.5mm) will be passed through a rectangular diamond - loaded resonator and induce an intense wakefield. A groove is cut on the diamond to enhance the field. Electric fields up to 0.5 GV/m will be present on the diamond surface to attempt to initiate breakdown. A surface analysis of the diamond is be performed before and after the beam test.

THPPC031	Commissioning of a 1.3-GHz Deflecting Cavity for Phase-Space Exchange at the Argonne Wakefield Accelerator	3350
	P. Piot Fermilab, Batavia, USA M.E. Conde, W. Gai, C.-J. Jing, R. Konecny, W. Liu, J.G. Power, Z.M. Yusof ANL, Argonne, USA D. Mihalcea, M.M. Rihaoui Northern Illinois University, DeKalb, Illinois, USA
	Funding: Work supported by DOE awards FG-02-08ER41532 and DE-AC02-06CH11357. A 1/2-1-1/2 cell normal-conducting 1.3-GHz deflecting cavity was recently installed at the Argonne Wakefield Accelerator. The cavity will soon be included in a transverse-to-longitudinal phase space exchanger that will eventually be used to shaped the current profile of AWA electron bunches in support of dielectric wakefield experimentS with enhanced transformer ratio. In this paper we report on the initial commissioning of the deflecting cavity including rf-conditioning and beam-based measurement of the deflecting strength.

Paper

Title

Page

Design and Development of the Diagnostic System for 75 MeV Electron Drive Beam for the AWA Upgrade

942

J.G. Power, S.P. Antipov, M.E. Conde, W. Gai, C.-J. Jing, W. Liu, E.E. Wisniewski, Z.M. Yusof
ANL, Argonne, USA

Funding: Work supported by High Energy Physics, Office of Science, US DOE
We report on the development of the diagnostic system for the ongoing upgrade to the Argonne Wakefield Accelerator (AWA) facility where the electron drive beam energy will be increased from 15 to 75 MeV. The facility will produce a wide dynamic range of drive bunch train formats ranging from a single microbunch of 100 pC to bunch trains of up to 32 bunches spaced by 769 ps with up to 100 nC per bunch. In addition to standard diagnostics, this drive bunch train format poses two challenges for the diagnostic system: (i) the close spacing of the drive bunches, 769 ps, makes resolving the individual pulses difficult and (ii) the dynamic range of the bunch charge varies by x1000. A critical parameter of the drive bunch train for the wakefield accelerator is the charge along the train. To measure this, we are planning to use a 15 GHz digital oscilloscope to read either a BPM or Bergoz FCT. To handle the large dynamic range of charge, the imaging system will make use of GigE Vision cameras and a distributed system of motorized lenses, with remote control of focus, zoom, and aperture, which are operated through terminal servers and RS232 controllers.

TUPPD070

Kelvin Probe Studies of a Cesium Telluride Photocathode for the AWA Photoinjector

1566

E.E. Wisniewski, K.C. Harkay, Z.M. Yusof
ANL, Argonne, USA
L.K. Spentzouris, J. Terry, D.G. Velazquez, E.E. Wisniewski
Illinois Institute of Technology, Chicago, Illinois, USA

Cesium telluride is an important photocathode as an electron source for particle accelerators. It has a relatively high quantum efficiency (>1%), is sufficiently robust in a photoinjector, and has a long lifetime. This photocathode is grown in-house for the new Argonne Wakefield Accelerator (AWA) to produce high charge per bunch (~50 nC). Here, we present a study of the "work function" of a cesium telluride photocathode using the Kelvin Probe technique. The study includes an investigation of the correlation between the quantum efficiency and the work function, the effect of photocathode aging, the surprising effect of UV exposure on the work function, and the puzzling behavior of the work function during and after photocathode rejuvenation via heating.

TUPPD071

Development of Cesium Telluride Photocathodes for the AWA Accelerator Upgrade

1569

Z.M. Yusof, M.E. Conde, W. Gai
ANL, Argonne, USA
L.K. Spentzouris, E.E. Wisniewski
Illinois Institute of Technology, Chicago, Illinois, USA

Funding: U.S. Department of Energy Office of Science under Contract No. DE-AC02-06CH11357.
Cesium telluride photocathodes have been fabricated for the Argonne Wakefield Accelerator (AWA) upgrade. The as-deposited photocathodes have consistently produced quantum efficiency values better than 10% with 254 nm light source and with variation of less than 5% over a circular area of 1.2 inches in diameter. We present various characterizations of the photocathode that have performed, including rejuvenation, lifetime, and performance in the L-band AWA photoinjector.

WEPPP025

A Test-bed for Future Linear Collider Technology: Argonne Wakefield Accelerator Facility (AWA)

2778

M.E. Conde, D.S. Doran, W. Gai, R. Konecny, W. Liu, J.G. Power, Z.M. Yusof
ANL, Argonne, USA
S.P. Antipov, C.-J. Jing
Euclid TechLabs, LLC, Solon, Ohio, USA
E.E. Wisniewski
Illinois Institute of Technology, Chicago, Illinois, USA

Funding: Work supported by the U.S. Department of Energy under contract No. DE-AC02-06CH11357.
Research at the AWA Facility has been focused on the development of electron beam driven wakefield structures. Accelerating gradients of up to 100 MV/m have been excited in dielectric loaded cylindrical structures operating in the microwave range of frequencies. Several upgrades, presently underway, will enable the facility to explore higher accelerating gradients, and also be able to generate longer RF pulses of higher intensity. The upgraded 75 MeV drive beam will consist of bunch trains of up to 32 bunches spaced by 0.77 ns with up to 100 nC per bunch. The RF pulses generated by the drive bunches are expected to reach GW power levels, establishing accelerating gradients of hundreds of MV/m.

WEPPD077

Generation of Picosecond Electron-bunch Trains with Variable Spacing Using a Multi-pulse Photocathode Laser

2705

P. Piot
Fermilab, Batavia, USA
M.E. Conde, W. Gai, C.-J. Jing, R. Konecny, W. Liu, J.G. Power, Z.M. Yusof
ANL, Argonne, USA
D. Mihalcea, P. Piot, M.M. Rihaoui
Northern Illinois University, DeKalb, Illinois, USA

Funding: Work supported by DOE awards FG-02-08ER41532 and DE-AC02-06CH11357.
We demonstrate the generation of a train of electron bunches with variable spacing at the Argonne Wakefield Accelerator. The photocathode ultraviolet laser pulse consists of a train of four pulses produced via polarization splitting using two alpha-BBO crystals. The photoemitted electron bunches are then manipulated in a horizontally-bending dogleg with variable longitudinal dispersion. A downstream vertically-deflecting cavity is then used to diagnose the temporal profile of the electron beam. The generation of a train composed of four bunches with tunable spacing is demonstrated. Such train of bunch could have application to, e.g., the resonant excitation of wakefield in dielectric-lined waveguides.

WEPPP041

Wakefield Breakdown Test of a Diamond-loaded Accelerating Structure at the AWA

2813

S.P. Antipov, J.E. Butler, C.-J. Jing, A. Kanareykin, P. Schoessow, S.S. Zuo
Euclid TechLabs, LLC, Solon, Ohio, USA
S. Baryshev, M.E. Conde, D.S. Doran, W. Gai, R. Konecny, J.G. Power, Z.M. Yusof
ANL, Argonne, USA

Funding: DOE SBIR
Diamond has been proposed as a dielectric material for dielectric loaded accelerating (DLA) structures. It has a very low microwave loss tangent, the highest available thermoconductive coefficient and high RF breakdown field. In this paper we report results from a wakefield breakdown test of diamond-loaded rectangular accelerating structure. The high charge beam from the AWA linac (~70 nC, σz = 2.5mm) will be passed through a rectangular diamond - loaded resonator and induce an intense wakefield. A groove is cut on the diamond to enhance the field. Electric fields up to 0.5 GV/m will be present on the diamond surface to attempt to initiate breakdown. A surface analysis of the diamond is be performed before and after the beam test.

THPPC031

Commissioning of a 1.3-GHz Deflecting Cavity for Phase-Space Exchange at the Argonne Wakefield Accelerator

3350

P. Piot
Fermilab, Batavia, USA
M.E. Conde, W. Gai, C.-J. Jing, R. Konecny, W. Liu, J.G. Power, Z.M. Yusof
ANL, Argonne, USA
D. Mihalcea, M.M. Rihaoui
Northern Illinois University, DeKalb, Illinois, USA

Funding: Work supported by DOE awards FG-02-08ER41532 and DE-AC02-06CH11357.
A 1/2-1-1/2 cell normal-conducting 1.3-GHz deflecting cavity was recently installed at the Argonne Wakefield Accelerator. The cavity will soon be included in a transverse-to-longitudinal phase space exchanger that will eventually be used to shaped the current profile of AWA electron bunches in support of dielectric wakefield experimentS with enhanced transformer ratio. In this paper we report on the initial commissioning of the deflecting cavity including rf-conditioning and beam-based measurement of the deflecting strength.