IPAC2012 - List of Authors (Spentzouris, L.K.)

Paper

Title

Page

Interaction of Muon Beam with Plasma Developed During Ionization Cooling

1110

S. Ahmed
JLAB, Newport News, Virginia, USA
K.B. Beard, T.J. Roberts
Muons, Inc, Batavia, USA
D.M. Kaplan, L.K. Spentzouris
Illinois Institute of Technology, Chicago, Illinois, USA

Muon collider has been envisioned as a future high energy lepton machine. High luminosity can be obtained by the ionization cooling – best suited for muons due to their short life time. In this cooling process, particles ionize material medium in which they lose momentum, thus the normalized emittance is reduced. The ionized medium is called plasma and the ionization density could increase due to the passage of multiple bunches through the material. This means that the incoming beams interact with plasma together with ionizing the medium used for cooling. It is, therefore, important to investigate the effects of background plasma on the incoming bunches. A comprehensive studies of muon beam propagation through plasma medium using EM particle-in-cell simulations. This computational study involves kinetic model, therefore, provides deep insight of the phenomena, which cannot be obtained by the conventional fluid model. The wakes excited by mu+ and mu- are different due to the beam polarity and depends on their relative densities. Externally applied axial magnetic field suppresses the wakes evolved during the interaction. The details of this study will be discussed in the paper.

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.

THXB01

Interaction of Muon Beam with Plasma Developed During Ionization Cooling

3200

S. Ahmed
JLAB, Newport News, Virginia, USA
K.B. Beard, T.J. Roberts
Muons, Inc, Batavia, USA
D.M. Kaplan, L.K. Spentzouris
Illinois Institute of Technology, Chicago, Illinois, USA

Muon collider has been envisioned as a future high energy lepton machine. High luminosity can be obtained by the ionization cooling – best suited for muons due to their short life time. In this cooling process, particles ionize material medium in which they lose momentum, thus the normalized emittance is reduced. The ionized medium is called plasma and the ionization density could increase due to the passage of multiple bunches through the material. This means that the incoming beams interact with plasma together with ionizing the medium used for cooling. It is, therefore, important to investigate the effects of background plasma on the incoming bunches. A comprehensive studies of muon beam propagation through plasma medium using EM particle-in-cell simulations. This computational study involves kinetic model, therefore, provides deep insight of the phenomena, which cannot be obtained by the conventional fluid model. The wakes excited by mu+ and mu- are different due to the beam polarity and depends on their relative densities. Externally applied axial magnetic field suppresses the wakes evolved during the interaction. The details of this study will be discussed in the paper.

Slides THXB01 [4.584 MB]

Paper	Title	Page
TUEPPB001	Interaction of Muon Beam with Plasma Developed During Ionization Cooling	1110
	S. Ahmed JLAB, Newport News, Virginia, USA K.B. Beard, T.J. Roberts Muons, Inc, Batavia, USA D.M. Kaplan, L.K. Spentzouris Illinois Institute of Technology, Chicago, Illinois, USA
	Muon collider has been envisioned as a future high energy lepton machine. High luminosity can be obtained by the ionization cooling – best suited for muons due to their short life time. In this cooling process, particles ionize material medium in which they lose momentum, thus the normalized emittance is reduced. The ionized medium is called plasma and the ionization density could increase due to the passage of multiple bunches through the material. This means that the incoming beams interact with plasma together with ionizing the medium used for cooling. It is, therefore, important to investigate the effects of background plasma on the incoming bunches. A comprehensive studies of muon beam propagation through plasma medium using EM particle-in-cell simulations. This computational study involves kinetic model, therefore, provides deep insight of the phenomena, which cannot be obtained by the conventional fluid model. The wakes excited by mu+ and mu- are different due to the beam polarity and depends on their relative densities. Externally applied axial magnetic field suppresses the wakes evolved during the interaction. The details of this study will be discussed in the paper.

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.

THXB01	Interaction of Muon Beam with Plasma Developed During Ionization Cooling	3200
	S. Ahmed JLAB, Newport News, Virginia, USA K.B. Beard, T.J. Roberts Muons, Inc, Batavia, USA D.M. Kaplan, L.K. Spentzouris Illinois Institute of Technology, Chicago, Illinois, USA
	Muon collider has been envisioned as a future high energy lepton machine. High luminosity can be obtained by the ionization cooling – best suited for muons due to their short life time. In this cooling process, particles ionize material medium in which they lose momentum, thus the normalized emittance is reduced. The ionized medium is called plasma and the ionization density could increase due to the passage of multiple bunches through the material. This means that the incoming beams interact with plasma together with ionizing the medium used for cooling. It is, therefore, important to investigate the effects of background plasma on the incoming bunches. A comprehensive studies of muon beam propagation through plasma medium using EM particle-in-cell simulations. This computational study involves kinetic model, therefore, provides deep insight of the phenomena, which cannot be obtained by the conventional fluid model. The wakes excited by mu+ and mu- are different due to the beam polarity and depends on their relative densities. Externally applied axial magnetic field suppresses the wakes evolved during the interaction. The details of this study will be discussed in the paper.
	Slides THXB01 [4.584 MB]