• T.J. Roberts
  Muons, Inc, Batavia
• D.M. Kaplan
  Illinois Institute of Technology, Chicago, Illinois

Funding: Work supported in part by USDOE STTR Grant DE FG02 08ER86281.

We describe an approach that can extend the utility of frictional cooling, originally developed for muon beams, to other particles and ions, producing beams of exceptionally low normalized emittance. Moreover, via this approach the small momentum acceptance typical of frictional cooling channels can be increased by two to three orders of magnitude, making it possible to handle much larger intensities with much higher transmission, while preserving the exceptionally low normalized emittance of the output. Simulation studies have been used to optimize the design and performance for a variety of ions and particles, and an inexpensive experiment has been designed to test and verify the concept and simulations, using alpha particles from a radioactive source.

• D. Huang
  IIT, Chicago, Illinois
• D.M. Kaplan
  Illinois Institute of Technology, Chicago, Illinois
• K.Y. Ng
  Fermilab, Batavia
• T.J. Roberts
  Muons, Inc, Batavia

Funding: Supported in part by USDOE Contract DE-FG02-6ER86281

The study of Muon beam optics is crucial for future Neutrino Factory and Muon Collider facilities. At present, the GEANT4-based simulation tools for Muon beam tracking such as G4beamline and G4MICE are based on single particle tracking without collective effects taken into account. However, it is known that collective effects such as space charge and wakefields for muons (in matters or vacuum) are not ignorable. As the first step, space charge computation has been implemented into muon tracking. The basic algorithm is particle to particle interactions through retarded electro-magnetic fields. The momentum impulse by collective effects is imposed on every particle at each collective step, and the G4beamline main code is used for tracking. Comparisons to LANL Parmela are illustrated and analyzed. Optimizations of the algorithm are also underway to gain less computing time and more accuracy. Moreover, the idea of enhancing ionization cooling efficiency by utilizing the collective effect due to polarized charges in matter appears to be possible, and the preliminary estimation has been done.

• T.J. Roberts, K.B. Beard
  Muons, Inc, Batavia
• S. Ahmed, D.M. Kaplan, L.K. Spentzouris
  Illinois Institute of Technology, Chicago, Illinois
• D. Huang
  IIT, Chicago, Illinois

Funding: Supported in part by USDOE STTR Grant DE-FG02-06ER86281

Most computer programs that calculate the trajectories of particles in accelerators assume that the particles travel in an evacuated chamber. The development of muon beams, which are needed for muon colliders and neutrino factories and are usually required to pass through matter, is limited by the lack of user-friendly numerical simulation codes that accurately calculate scattering and energy loss in matter. Geant4 is an internationally supported tracking toolkit that was developed to simulate particle interactions in large detectors for high energy physics experiments, and includes most of what is known about the interactions of particles and matter. Geant4 has been partially adapted in a program called G4beamline to develop muon beam line designs. The program is now being developed and debugged by a larger number of accelerator physicists studying muon cooling channel designs and other applications. Space-charge effects and muon polarization are new features that are being implemented.