PAC2013 - List of Authors (Stratakis, D.)

Paper	Title	Page
TUPBA11	TOWARDS A GLOBAL OPTIMIZATION OF THE MUON ACCELERATOR FRONT END	547
	H. K. Sayed, J.S. Berg, H.G. Kirk, R.B. Palmer, D. Stratakis BNL, Upton, Long Island, New York, USA K.T. McDonald PU, Princeton, New Jersey, USA D.V. Neuffer Fermilab, Batavia, USA J. Qiang, R.D. Ryne LBNL, Berkeley, California, USA
	The baseline design for the neutrino factory and muon collider front end consists of a five major components, namely the muon production target, decay channel, buncher, phase rotator, and the ionization cooling channel. Although each of the mentioned systems has a complex design which is optimized for the best performance with its own set of local objectives, the integration of all of them into one system requires a global optimization to insure the effectiveness of the local objectives and overall performance. This global optimization represents a highly constrained multi-objective optimization problem. The objectives aimed for are the number of muons captured into a stable bunches and their transverse and longitudinal emittances. These objectives are constrained by the momentum and dynamic acceptance of the subsequent acceleration systems in addition to the overall cost. A multi-objective global evolutionary algorithm is employed to address such a challenge. In this study a statement of optimization strategy is discussed along with preliminary results of the optimization.

THPHO04	Linear Analysis for Several 6-D Ionization Cooling Lattices	1304
	J.S. Berg, R.B. Palmer, D. Stratakis BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. In muon accelerators, ionization cooling is the only viable option for reducing the muon beam emittance to values necessary for a muon collider. An ionization cooling lattice requires a large momentum acceptance, small beta functions, an extremely large dynamic aperture, and a modeset amount of dispersion to have good performance. The latter values are a function of beam momentum. One step in understanding the lattice performance is to determine these quantities for a lattice cell being studied. This is modestly more complex than usual since the lattice is generally highly coupled. We first review the general method for computing these quantities for a general lattice. Then we look at several lattices of interest, compute these quantities, and relate their values and momentum dependencies to the performance of the lattices.

THPHO05	A Planar Snake Muon Ionization Cooling Lattice	1307
	R.B. Palmer, J.S. Berg, D. Stratakis BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. Muon Colliders require cooling in six dimensions (x, x', y, y', t, E). Several ionization 6D cooling lattices, using vacuum acceleration, are reviewed: RFOFO lattices, both curved* and rectilinear cool one sign to low emittances; A Helical FOFO snake* cools both signs, but not to low emittances. A Planar Snake**** lattice is proposed that cools both muon signs, and appears suitable for low emittances. The parameters and performance for an example suitable for the early stages of cooling is given. P. Snopok et al., IJMPA 24, p. 987 (2009). V. Balbekov, Proc. of PAC 2003, Portland, OR, p. 2017 (2003). Y. Alexahin, AIP Conf. Proc. 1222, p. 313 (2010). **R.B. Palmer, “6D Cooling in Periodic Lattices”, June 6, 2013, http://www.cap.bnl.gov/AAG/GroupMeetings/

THPHO12	A High-Performance Rectilinear FOFO Channel for Muon Cooling	1328
	D. Stratakis, J.S. Berg, R.B. Palmer BNL, Upton, Long Island, New York, USA V. Balbekov Fermilab, Batavia, USA
	Funding: This work is funded by US Dept. of Energy grant numbers DE AC02-98CH10886 An ionization cooling channel is a tightly spaced lattice containing absorbers for reducing the momentum of the muon beam, rf cavities for restoring the longitudinal momentum and solenoids for focusing the beam. Such a lattice is an essential step for a Muon Collider. Here, we explore two different schemes for designing ionization cooling channels for muon related applications. The first is an upward helical lattice commonly known as the Guggenheim channel. The second is a novel linear channel with either wedge or block absorbers for cooling and tilted solenoids for emittance exchange. The latter scheme addresses several of the engineering challenges of a conventional Guggenheim channel. We incorporate both schemes into a new lattice design for a muon collider, and examine their performance numerically. We optimize the designs and compare the conductor current densities requirements for all of the simulated scenarios.

THPHO13	Space-Charge Limitations on the Final Stages of a Muon Collider Cooling Channel	1331
	D. Stratakis, J.S. Berg, R.B. Palmer BNL, Upton, Long Island, New York, USA D.P. Grote LLNL, Livermore, California, USA
	Funding: This work is funded by US Dept. of Energy grant numbers DE AC02-98CH10886. Muon Colliders use ionization cooling to reduce the emittance of the muon beam prior to acceleration. A Muon Collider requires the normalized longitudinal emittance to be less than 2 mm while the normalized transverse emittance is a few hundred μm. At the last stages of the cooling channel, the bunch has 4×10¹² muons, an average momentum of 200 MeV/c, and an rms bunch of 2 cm. With this beam intensity and relatively low momentum, we expect space charge effects to have a significant impact on beam dynamics. Currently, codes that could study both space-charge and particle-matter-interaction are limited. Here, with the aid of the particle-in-cell code Warp, a model is developed to examine space-charge for muon cooling lattices and some recent results are presented. Space-charge compensation solutions are discussed and the minimum cooling emittance as a function of the beam charge is identified.

Paper

Title

Page

TOWARDS A GLOBAL OPTIMIZATION OF THE MUON ACCELERATOR FRONT END

547

H. K. Sayed, J.S. Berg, H.G. Kirk, R.B. Palmer, D. Stratakis
BNL, Upton, Long Island, New York, USA
K.T. McDonald
PU, Princeton, New Jersey, USA
D.V. Neuffer
Fermilab, Batavia, USA
J. Qiang, R.D. Ryne
LBNL, Berkeley, California, USA

The baseline design for the neutrino factory and muon collider front end consists of a five major components, namely the muon production target, decay channel, buncher, phase rotator, and the ionization cooling channel. Although each of the mentioned systems has a complex design which is optimized for the best performance with its own set of local objectives, the integration of all of them into one system requires a global optimization to insure the effectiveness of the local objectives and overall performance. This global optimization represents a highly constrained multi-objective optimization problem. The objectives aimed for are the number of muons captured into a stable bunches and their transverse and longitudinal emittances. These objectives are constrained by the momentum and dynamic acceptance of the subsequent acceleration systems in addition to the overall cost. A multi-objective global evolutionary algorithm is employed to address such a challenge. In this study a statement of optimization strategy is discussed along with preliminary results of the optimization.

THPHO04

Linear Analysis for Several 6-D Ionization Cooling Lattices

1304

J.S. Berg, R.B. Palmer, D. Stratakis
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
In muon accelerators, ionization cooling is the only viable option for reducing the muon beam emittance to values necessary for a muon collider. An ionization cooling lattice requires a large momentum acceptance, small beta functions, an extremely large dynamic aperture, and a modeset amount of dispersion to have good performance. The latter values are a function of beam momentum. One step in understanding the lattice performance is to determine these quantities for a lattice cell being studied. This is modestly more complex than usual since the lattice is generally highly coupled. We first review the general method for computing these quantities for a general lattice. Then we look at several lattices of interest, compute these quantities, and relate their values and momentum dependencies to the performance of the lattices.

THPHO05

A Planar Snake Muon Ionization Cooling Lattice

1307

R.B. Palmer, J.S. Berg, D. Stratakis
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Muon Colliders require cooling in six dimensions (x, x', y, y', t, E). Several ionization 6D cooling lattices, using vacuum acceleration, are reviewed: RFOFO lattices, both curved* and rectilinear** cool one sign to low emittances; A Helical FOFO snake*** cools both signs, but not to low emittances. A Planar Snake**** lattice is proposed that cools both muon signs, and appears suitable for low emittances. The parameters and performance for an example suitable for the early stages of cooling is given.
*P. Snopok et al., IJMPA 24, p. 987 (2009).
**V. Balbekov, Proc. of PAC 2003, Portland, OR, p. 2017 (2003).
***Y. Alexahin, AIP Conf. Proc. 1222, p. 313 (2010).
****R.B. Palmer, “6D Cooling in Periodic Lattices”, June 6, 2013, http://www.cap.bnl.gov/AAG/GroupMeetings/

THPHO12

A High-Performance Rectilinear FOFO Channel for Muon Cooling

1328

D. Stratakis, J.S. Berg, R.B. Palmer
BNL, Upton, Long Island, New York, USA
V. Balbekov
Fermilab, Batavia, USA

Funding: This work is funded by US Dept. of Energy grant numbers DE AC02-98CH10886
An ionization cooling channel is a tightly spaced lattice containing absorbers for reducing the momentum of the muon beam, rf cavities for restoring the longitudinal momentum and solenoids for focusing the beam. Such a lattice is an essential step for a Muon Collider. Here, we explore two different schemes for designing ionization cooling channels for muon related applications. The first is an upward helical lattice commonly known as the Guggenheim channel. The second is a novel linear channel with either wedge or block absorbers for cooling and tilted solenoids for emittance exchange. The latter scheme addresses several of the engineering challenges of a conventional Guggenheim channel. We incorporate both schemes into a new lattice design for a muon collider, and examine their performance numerically. We optimize the designs and compare the conductor current densities requirements for all of the simulated scenarios.

THPHO13

Space-Charge Limitations on the Final Stages of a Muon Collider Cooling Channel

1331

D. Stratakis, J.S. Berg, R.B. Palmer
BNL, Upton, Long Island, New York, USA
D.P. Grote
LLNL, Livermore, California, USA

Funding: This work is funded by US Dept. of Energy grant numbers DE AC02-98CH10886.
Muon Colliders use ionization cooling to reduce the emittance of the muon beam prior to acceleration. A Muon Collider requires the normalized longitudinal emittance to be less than 2 mm while the normalized transverse emittance is a few hundred μm. At the last stages of the cooling channel, the bunch has 4×10¹² muons, an average momentum of 200 MeV/c, and an rms bunch of 2 cm. With this beam intensity and relatively low momentum, we expect space charge effects to have a significant impact on beam dynamics. Currently, codes that could study both space-charge and particle-matter-interaction are limited. Here, with the aid of the particle-in-cell code Warp, a model is developed to examine space-charge for muon cooling lattices and some recent results are presented. Space-charge compensation solutions are discussed and the minimum cooling emittance as a function of the beam charge is identified.