COOL2015 - List of Authors (Derbenev, Y.S.)

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TUWAUD02

Affordable, Scalable, and Convincing 6-d Muon Cooling Demonstrations

R.P. Johnson
Muons, Inc, Illinois, USA
S.A. Bogacz, Y.S. Derbenev, V.S. Morozov, A.V. Sy
JLab, Newport News, Virginia, USA
K. Yonehara
Fermilab, Batavia, Illinois, USA

The number of applications that could benefit from effective, affordable muon cooling include stopping muon beams for rare decay searches and spin resonance, intermediate energy beams for neutrino factories and cargo scanning, and muon colliders for HIggs factories and the energy frontier. The simple ionization cooling equation implies that if you have a low-Z energy absorber in a strong magnetic field, sufficient RF to contain the beam and replace the lost energy, and some mechanism for emittance exchange, you can achieve low 6-d emittance down to the limit implied by multiple scattering. The first cooling simulations that were based on a ring were exciting and encouraging. Unfortunately, injection difficulties, beam loading of RF cavities and energy absorbers, and the need to modify cooling parameters as the beam cools have led us away from a ring towards a cooling channel. An effective demonstration experiment must show that the final muon beam parameters to achieve the required luminosity can be achieved at an acceptable cost. We discuss the possibility that a demonstration experiment is a section of a practical, high performance cooling channel.

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TUWAUD03

Study of Helical Cooling Channel for Intense Muon Source

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K. Yonehara
Fermilab, Batavia, Illinois, USA
Y.S. Derbenev
JLab, Newport News, Virginia, USA
R.P. Johnson
Muons, Inc, Illinois, USA

Linear beam dynamics of muons in a helical cooling channel is non-trivial. Betatron oscillation in the channel is induced by coupling of motions in xyz-planes. As a result, the analytic eigen values are very complicated. The cooling decrements are controlled by tuning coupling strength. The helical dynamic parameters are translated into the conventional accelerator physics term. Non-linear dynamics in the helical channel is studied by using the conventional accelerator technique. The beam-plasma interaction in a high-pressure hydrogen gas-filled RF cavity is a new physics process and important to design the cooling channel. Machine development of helical beam elements is also shown in this presentation.

Slides TUWAUD03 [6.220 MB]

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TUWAUD04

Progress on Parametric-resonance Ionization Cooling

77

V.S. Morozov, Y.S. Derbenev, A.V. Sy
JLab, Newport News, Virginia, USA
A. Afanasev
GWU, Washington, USA
R.P. Johnson
Muons, Inc, Illinois, USA
J.A. Maloney
Northern Illinois University, DeKalb, Illinois, USA

Funding: Work supported in part by U.S. DOE STTR Grants DE-SC0005589 and DE-SC0007634. Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
Proposed next-generation muon collider will require major technical advances to achieve the rapid muon beam cooling requirements. Parametric-resonance Ionization Cooling (PIC) is proposed as the final 6D cooling stage of a high-luminosity muon collider. In PIC, a half-integer parametric resonance causes strong focusing of a muon beam at appropriately placed energy absorbers while ionization cooling limits the beam's angular spread. Combining muon ionization cooling with parametric resonant dynamics in this way should then allow much smaller final transverse muon beam sizes than conventional ionization cooling alone. One of the PIC challenges is compensation of beam aberrations over a sufficiently wide parameter range while maintaining the dynamical stability with correlated behavior of the horizontal and vertical betatron motion and dispersion. We explore use of a coupling resonance to reduce the dimensionality of the problem and to shift the dynamics away from non-linear resonances. PIC simulations are presented.

Slides TUWAUD04 [2.043 MB]

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TUXAUD03

ERL Cooling Ring Concepts for the MEIC

S.V. Benson, Y.S. Derbenev, D. Douglas, F.E. Hannon, F. Marhauser, R.A. Rimmer, C. Tennant, H. Wang, H. Zhang, Y. Zhang
JLab, Newport News, Virginia, USA

Funding: This work was supported by U.S. DOE Contract No. DE-AC05-84-ER40150
The MEIC design at Jefferson Lab will collide electrons in a storage ring with ions in a separate ring. In order to enhance the luminosity, the ions must be cooled in a cooling channel. The required current and charge necessary to cool the ions is on the order of 200 mA and 420 pC at an electron energy as high as 55 MeV. This is too high for a DC accelerator such as a pelletron and so the electron beam must be provided by an Energy Recovery Linac (ERL). This presentation will discuss two options for such an ERL and show some early results of modeling and simulation for these designs. At least at the highest energy, the beam quality seems to be good enough to provide a reasonable cooling rate for the ions.

Slides TUXAUD03 [3.763 MB]

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WEWAUD02

Matched Electron Cooling

Y.S. Derbenev
JLab, Newport News, Virginia, USA

Electron cooling of an ion beam is considered in a ring with coupled optics matched with the solenoid of a cooling section. Betatron motion of ions is then represented as a superposition of the two independent circular modes of the two uncorrelated uncoupled canonical emittances, similar to the drift and cyclotron modes of an electron beam in a solenoid. Then cooling of the ion cyclotron mode is not limited by the ion space charge. Cooling of the drift mode is attained by use of dispersion of both beams introduced to the solenoid section. Ion optics organized in this way allows one to drastically diminish the space charge impact on the 4D emittance at beam stacking in a booster and cooling in a collider ring, thus enhancing the cooling rate. Equilibrium due to the IBS is estimated. We also evaluate the gain in luminosity by means of a round to flat beam transformation around the Interaction Point.
*Authored by Jefferson Science Associates, LLC under U.S. DOE Contracts No. DE-AC05-06OR23177 and DE-AC02-06CH11357.

Slides WEWAUD02 [0.458 MB]

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WEXAUD03

Space Charge and CSR Microwave Physics in a Circulated Electron Cooler

R. Li, S.V. Benson, Y.S. Derbenev, D. Douglas, C. Tennant, Y. Zhang
JLab, Newport News, Virginia, USA
E.W. Nissen
CERN, Geneva, Switzerland
C.-Y. Tsai
Virginia Polytechnic Institute and State University, Blacksburg, Virginia, USA

Funding: This work is supported by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
Circulator cooler ring (CCR) was proposed * as a scheme to alleviate the high demand for the average current of the cooling beam from the electron source. However, transporting the high-brightness cooling beam through CCR for multiple turns, while preserving the phase space quality of the beam, presents significant challenges for the CCR design **. In this presentation, we describe our studies on the microbunching instability (uBI) induced by the CSR and longitudinal space charge interactions, and present results of microwave physics for a non-magnetized beam circulating in an early design of CCR *** of MEIC. It is envisioned that CCR designed for a magnetized beam will have much reduced microbunching effects. A future plan for such study will be discussed.
* R. Brinkmann, et al., Proc. of EPAC98, p345 (1998)
** C. Tennant and D. Douglas, JLAB-TN-12-027 (2012)
*** C. Tsai et al., this workshop (2015)

Slides WEXAUD03 [2.848 MB]

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