Advanced Concepts and Future Directions
Accel/Storage Rings 11: e-coolers and Cooling Techniques
Paper Title Page
MOP002 Tapered Six-Dimensional Cooling Channel for a Muon Collider 106
 
  • R. B. Palmer, R.C. Fernow
    BNL, Upton, Long Island, New York, USA
 
  A high-luminosity muon collider requires a reduction of the six-dimensional emittance of the captured muon beam by a factor of approximately 106. Most of this cooling takes place in a dispersive channel that simultaneously reduces all six phase space dimensions. We describe a tapered 6D cooling channel that should meet the requirements of a muon collider. The parameters of the channel are given and preliminary simulations are shown of the expected performance.  
 
MOP064 Asymmetric Laser Radiant Cooling in Storage Rings 229
 
  • E.V. Bulyak
    NSC/KIPT, Kharkov, Ukraine
  • J. Urakawa
    KEK, Ibaraki, Japan
  • F. Zimmermann
    CERN, Geneva, Switzerland
 
  Laser pulses with small spatial and temporal dimensions can interact with a fraction of the electron bunches circulating in Compton storage rings. We studied synchrotron dynamics of such bunches when laser photons scatter off from the electrons with energy higher than the synchronous energy. In this case of ‘asymmetric cooling', as shown theoretically, the stationary energy spread is much smaller than under conditions of regular scattering; the oscillations are damped faster. Coherent oscillations of large amplitude may be damped in one synchrotron period, which makes this method feasible for injection the bunches into a ring in the longitudinal phase space. The theoretical results are validated with simulations.  
 
MOP066 Effects of e-beam Parameters on Coherent Electron Cooling 232
 
  • S.D. Webb, V. Litvinenko, G. Wang
    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.
Coherent Electron Cooling (CeC) requires detailed con- trol of the phase between the hadron an the FEL-amplified wave packet. This phase depends on local electron beam parameters such as the energy spread and the peak current. In this paper, we examine the effects of local density variations on the cooling rates for CeC.
 
 
MOP067 Vlasov and PIC Simulations of a Modulator Section for Coherent Electron Cooling 235
 
  • G.I. Bell, D.L. Bruhwiler, I.V. Pogorelov, B.T. Schwartz
    Tech-X, Boulder, Colorado, USA
  • Y. Hao, V. Litvinenko, G. Wang
    BNL, Upton, Long Island, New York, USA
 
  Funding: This work is supported by the US DOE Office of Science, Office of Nuclear Physics, grant numbers DE-SC0000835 and DE-FC02-07ER41499. Resources of NERSC were used under contract No. DE-AC02-05CH11231.
Next generation ion colliders will require effective cooling of high-energy hadron beams. Coherent electron cooling (CEC) can in principle cool relativistic hadron beams on orders-of-magnitude shorter time scales than other techniques. We present Vlasov-Poisson and delta-f particle-in-cell (PIC) simulations of a CEC modulator section. These simulations correctly capture the subtle time and space evolution of the density and velocity wake imprinted on the electron distribution via anisotropic Debye shielding of a drifting ion. We consider 1D and 2D reduced versions of the problem, and compare the exact solutions of Wang and Blaskiewicz with Vlasov-Poisson and delta-f PIC simulations. We also consider interactions under non-ideal conditions where there is a density gradient in the electron distribution, and present simulations of the ion wake.
* V.N. Litvinenko and Y.S. Derbenev, Phys. Rev. Lett. 102, 114801 (2009).
 
 
MOP074 Simulations of a Single-Pass Through a Coherent Electron Cooler for 40 Gev/n Au+79 244
 
  • B.T. Schwartz, D.L. Bruhwiler, I.V. Pogorelov
    Tech-X, Boulder, Colorado, USA
  • Y. Hao, V. Litvinenko, G. Wang
    BNL, Upton, Long Island, New York, USA
  • S. Reiche
    PSI, Villigen, Switzerland
 
  Funding: US DOE Office of Science, Office of Nuclear Physics, grant No.’s DE-FG02-08ER85182 and DE-FC02-07ER41499. NERSC resources were supported by the DOE Office of Science, contract No. DE-AC02-05CH11231.
Increasing the luminosity of ion beams in particle accelerators is critical for the advancement of nuclear and particle physics. Coherent electron cooling promises to cool high-energy hadron beams significantly faster than electron cooling or stochastic cooling. Here we show simulations of a single pass through a coherent electron cooler, which consists of a modulator, a free-electron laser, and a kicker. In the modulator the electron beam copropagates with the ion beam, which perturbs the electron beam density according to the ion positions. The FEL, which both amplifies and imparts wavelength-scale modulation on the electron beam. The strength of modulated electric fields determines how much they accelerate or decelerate the ions when electron beam recombines with the dispersion-shifted hadrons in the kicker region. From these field strengths we estimate the cooling time for a gold ion with a specific longitudinal velocity.
* Vladimir N. Litvinenko, Yaroslav S. Derbenev, Physical Review Letters 102, 114801 (2009)
 
 
THOBN2 Muon Collider Final Cooling in 30-50 T Solenoids 2061
 
  • R. B. Palmer, R.C. Fernow
    BNL, Upton, Long Island, New York, USA
  • J.L. Lederman
    UCLA, Los Angeles, California, USA
 
  Muon ionization cooling to the required transverse emittance of 25 microns can be achieved with liquid hydrogen in high field solenoids, provided that the momenta are low enough. At low momenta, the longitudinal emittance rises because of the negative slope of energy loss versus energy. Assuming initial emittances that have been achieved in six dimensional cooling simulations, optimized designs are given using solenoid fields limited to 30, 40, and 50 T. The required final emittances are achieved for the two higher field cases.  
slides icon Slides THOBN2 [0.319 MB]  
 
THOBN3 Proof-of-Principle Experiment for FEL-based Coherent Electron Cooling 2064
 
  • V. Litvinenko, I. Ben-Zvi, J. Bengtsson, A.V. Fedotov, Y. Hao, D. Kayran, G.J. Mahler, W. Meng, T. Roser, B. Sheehy, R. Than, J.E. Tuozzolo, G. Wang, S.D. Webb, V. Yakimenko
    BNL, Upton, Long Island, New York, USA
  • G.I. Bell, D.L. Bruhwiler, B.T. Schwartz
    Tech-X, Boulder, Colorado, USA
  • A. Hutton, G.A. Krafft, M. Poelker, R.A. Rimmer
    JLAB, Newport News, Virginia, USA
 
  Funding: This work is supported the U.S. Department of Energy
Coherent electron cooling (CEC) has a potential to significantly boost luminosity of high-energy, high-intensity hadron-hadron and electron-hadron colliders*. In a CEC system, a hadron beam interacts with a cooling electron beam. A perturbation of the electron density caused by ions is amplified and fed back to the ions to reduce the energy spread and the emittance of the ion beam. To demonstrate the feasibility of CEC we propose a proof-of-principle experiment at RHIC using one of JLab’s SRF cryo-modules. In this paper, we describe the experimental setup for CeC installed into one of RHIC's interaction regions. We present results of analytical estimates and results of initial simulations of cooling a gold-ion beam at 40 GeV/u energy via CeC.
* Vladimir N. Litvinenko, Yaroslav S. Derbenev, Physical Review Letters 102, 114801
 
slides icon Slides THOBN3 [1.379 MB]