IPAC2012 - List of Authors (Afanasev, A.)

Paper	Title	Page
TUPPD011	Studies of the Twin Helix Parametric-resonance Ionization Cooling Channel with COSY INFINITY	1428
	J.A. Maloney, K.B. Beard, R.P. Johnson Muons, Inc, Batavia, USA A. Afanasev GWU, Washington, USA S.A. Bogacz, Y.S. Derbenev, V.S. Morozov JLAB, Newport News, Virginia, USA B. Erdelyi Northern Illinois University, DeKalb, Illinois, USA
	Funding: Supported in part by SBIR Grant DE-SC00005589. Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. A primary technical challenge to the design of a high luminosity muon collider is an effective beam cooling system. An epicyclic twin-helix channel utilizing parametric-resonance ionization cooling has been proposed for the final 6D cooling stage. A proposed design of this twin-helix channel is presented that utilizes correlated optics between the horizontal and vertical betatron periods to simultaneously focus transverse motion of the beam in both planes. Parametric resonance is induced in both planes via a system of helical quadrupole harmonics. Ionization cooling is achieved via periodically placed wedges of absorbing material, with intermittent rf cavities restoring longitudinal momentum necessary to maintain stable orbit of the beam. COSY INFINITY is utilized to simulate the theory at first order. The motion of particles around a hyperbolic fixed point is tracked. Comparison is made between the EPIC cooling channel and standard ionization cooling effects. Cooling effects are measured, after including stochastic effects, for both a single particle and a distribution of particles.

TUPPD033	Conceptual Design of a Positron-annihilation System for Generation of Quasi-monochromatic Gamma Rays	1476
	R.J. Abrams, C.M. Ankenbrandt, K.B. Beard, G. Flanagan, R.P. Johnson, C. Y. Yoshikawa Muons, Inc, Batavia, USA A. Afanasev GWU, Washington, USA
	A conceptual design is presented for a system consisting of the following: an electron accelerator and production target to produce positrons, a dipole magnet and wedge to compress the positron momenta to be nearly monochromatic, a magnetic transport system to focus and direct the positrons to a converter, and a converter in which the positrons annihilate in flight to produce quasi-monochromatic gamma rays. The system represented is designed to produce ~10 MeV gammas, but it can also be designed for other energies.

TUPPD083	Raising Photoemission Efficiency with Surface Acoustic Waves	1596
	A. Afanasev, F. Hassani, C.E. Korman GWU, Washington, USA V.G. Dudnikov, R.P. Johnson Muons, Inc, Batavia, USA M. Poelker, K.E.L. Surles-Law JLAB, Newport News, Virginia, USA
	Funding: Supported in part by DOE STTR Grant DE-SC0006256. Notice: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177 We are developing a novel technique that may help increase the efficiency and reduce costs of photoelectron sources used at electron accelerators. The technique is based on the use of Surface Acoustic Waves (SAW) in piezoelectric materials, such as GaAs, that are commonly used as photocathodes. Piezoelectric fields produced by the traveling SAW spatially separate electrons and holes, reducing their probability of recombination, thereby enhancing the photoemission quantum efficiency of the photocathode. Additional advantages could be increased polarization provided by the enhanced mobility of charge carriers that can be controlled by the SAW and the ionization of optically-generated excitons resulting in the creation of additional electron-hole pairs. It is expected that these novel features will reduce the cost of accelerator operation. A theoretical model for photoemission in the presence of SAW has been developed, and experimental tests of the technique are underway.

WEPPP005	Progress on Muon Parametric-resonance Ionization Cooling Channel Development	2729
	V.S. Morozov, Y.S. Derbenev JLAB, Newport News, Virginia, USA A. Afanasev GWU, Washington, USA K.B. Beard, R.P. Johnson Muons, Inc, Batavia, USA B. Erdelyi, J.A. Maloney Northern Illinois University, DeKalb, Illinois, USA
	Funding: Supported in part by DOE SBIR grant DE-SC0005589. Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. Parametric-resonance Ionization Cooling (PIC) is intended as the final 6D cooling stage of a high-luminosity muon collider. To implement PIC, a continuous-field twin-helix magnetic channel was developed. A 6D cooling with stochastic effects off is demonstrated in a GEANT4/G4beamline model of a system where wedge-shaped Be absorbers are placed at the appropriate dispersion points in the twin-helix channel and are followed by short rf cavities. To proceed to cooling simulations with stochastics on, compensation of the beam aberrations from one absorber to another is required. Initial results on aberration compensation using a set of various-order continuous multipole fields are presented. As another avenue to mitigate the aberration effect, we optimize the cooling channel’s period length. We observe a parasitic parametric resonance naturally occurring in the channel’s horizontal plane due to the periodic beam energy modulation caused by the absorbers and rf. We discuss options for compensating this resonance and/or properly combining it with the induced half-integer parametric resonance needed for PIC. The U.S. Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce this manuscript for U.S. Government purposes.

Paper

Title

Page

Studies of the Twin Helix Parametric-resonance Ionization Cooling Channel with COSY INFINITY

1428

J.A. Maloney, K.B. Beard, R.P. Johnson
Muons, Inc, Batavia, USA
A. Afanasev
GWU, Washington, USA
S.A. Bogacz, Y.S. Derbenev, V.S. Morozov
JLAB, Newport News, Virginia, USA
B. Erdelyi
Northern Illinois University, DeKalb, Illinois, USA

Funding: Supported in part by SBIR Grant DE-SC00005589. Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
A primary technical challenge to the design of a high luminosity muon collider is an effective beam cooling system. An epicyclic twin-helix channel utilizing parametric-resonance ionization cooling has been proposed for the final 6D cooling stage. A proposed design of this twin-helix channel is presented that utilizes correlated optics between the horizontal and vertical betatron periods to simultaneously focus transverse motion of the beam in both planes. Parametric resonance is induced in both planes via a system of helical quadrupole harmonics. Ionization cooling is achieved via periodically placed wedges of absorbing material, with intermittent rf cavities restoring longitudinal momentum necessary to maintain stable orbit of the beam. COSY INFINITY is utilized to simulate the theory at first order. The motion of particles around a hyperbolic fixed point is tracked. Comparison is made between the EPIC cooling channel and standard ionization cooling effects. Cooling effects are measured, after including stochastic effects, for both a single particle and a distribution of particles.

TUPPD033

Conceptual Design of a Positron-annihilation System for Generation of Quasi-monochromatic Gamma Rays

1476

R.J. Abrams, C.M. Ankenbrandt, K.B. Beard, G. Flanagan, R.P. Johnson, C. Y. Yoshikawa
Muons, Inc, Batavia, USA
A. Afanasev
GWU, Washington, USA

A conceptual design is presented for a system consisting of the following: an electron accelerator and production target to produce positrons, a dipole magnet and wedge to compress the positron momenta to be nearly monochromatic, a magnetic transport system to focus and direct the positrons to a converter, and a converter in which the positrons annihilate in flight to produce quasi-monochromatic gamma rays. The system represented is designed to produce ~10 MeV gammas, but it can also be designed for other energies.

TUPPD083

Raising Photoemission Efficiency with Surface Acoustic Waves

1596

A. Afanasev, F. Hassani, C.E. Korman
GWU, Washington, USA
V.G. Dudnikov, R.P. Johnson
Muons, Inc, Batavia, USA
M. Poelker, K.E.L. Surles-Law
JLAB, Newport News, Virginia, USA

Funding: Supported in part by DOE STTR Grant DE-SC0006256. Notice: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177
We are developing a novel technique that may help increase the efficiency and reduce costs of photoelectron sources used at electron accelerators. The technique is based on the use of Surface Acoustic Waves (SAW) in piezoelectric materials, such as GaAs, that are commonly used as photocathodes. Piezoelectric fields produced by the traveling SAW spatially separate electrons and holes, reducing their probability of recombination, thereby enhancing the photoemission quantum efficiency of the photocathode. Additional advantages could be increased polarization provided by the enhanced mobility of charge carriers that can be controlled by the SAW and the ionization of optically-generated excitons resulting in the creation of additional electron-hole pairs. It is expected that these novel features will reduce the cost of accelerator operation. A theoretical model for photoemission in the presence of SAW has been developed, and experimental tests of the technique are underway.

WEPPP005

Progress on Muon Parametric-resonance Ionization Cooling Channel Development

2729

V.S. Morozov, Y.S. Derbenev
JLAB, Newport News, Virginia, USA
A. Afanasev
GWU, Washington, USA
K.B. Beard, R.P. Johnson
Muons, Inc, Batavia, USA
B. Erdelyi, J.A. Maloney
Northern Illinois University, DeKalb, Illinois, USA

Funding: Supported in part by DOE SBIR grant DE-SC0005589. Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
Parametric-resonance Ionization Cooling (PIC) is intended as the final 6D cooling stage of a high-luminosity muon collider. To implement PIC, a continuous-field twin-helix magnetic channel was developed. A 6D cooling with stochastic effects off is demonstrated in a GEANT4/G4beamline model of a system where wedge-shaped Be absorbers are placed at the appropriate dispersion points in the twin-helix channel and are followed by short rf cavities. To proceed to cooling simulations with stochastics on, compensation of the beam aberrations from one absorber to another is required. Initial results on aberration compensation using a set of various-order continuous multipole fields are presented. As another avenue to mitigate the aberration effect, we optimize the cooling channel’s period length. We observe a parasitic parametric resonance naturally occurring in the channel’s horizontal plane due to the periodic beam energy modulation caused by the absorbers and rf. We discuss options for compensating this resonance and/or properly combining it with the induced half-integer parametric resonance needed for PIC.
The U.S. Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce this manuscript for U.S. Government purposes.