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Yonehara, K.

Paper Title Page
MOPAN117 Magnet System for Helical Muon Cooling Channels 443
  • S. A. Kahn, M. Alsharo'a, R. P. Johnson
    Muons, Inc, Batavia
  • V. Kashikhin, V. S. Kashikhin, K. Yonehara, A. V. Zlobin
    Fermilab, Batavia, Illinois
  Funding: Supported in part by STTR Grant DE-FG02-04ER86191.

A helical cooling channel consisting of a pressurized gas absorber imbedded in a magnetic channel that provides superimposed solenoidal, helical dipole and helical quadrupole fields has shown considerable promise in providing six-dimensional cooling of muon beams. The analysis of this muon cooling technique with both analytic and simulation studies has shown significant reduction of muon phase space. A particular channel that has been simulated is divided into four segments each with progressively stronger fields and smaller apertures to reduce the equilibrium emittance so that more cooling can occur. The fields in the helical channel are sufficiently large that the conductor for segments 1 and 2 can be Nb3Sn and the conductor for segments 3 and 4 may need to be high temperature superconductor. This paper will describe the magnetic specifications for the channel and two conceptual designs on how to implement the magnetic channel.

MOPAS012 Magnets for the MANX 6-D Muon Cooling Demonstration Experiment 461
  • V. S. Kashikhin, V. Kashikhin, M. J. Lamm, G. Romanov, K. Yonehara, A. V. Zlobin
    Fermilab, Batavia, Illinois
  • R. P. Johnson, S. A. Kahn, T. J. Roberts
    Muons, Inc, Batavia
  Funding: Supported in part by DOE STTR grant DE-FG02-04ER86191

MANX is a 6-dimensional muon ionization-cooling experiment that has been proposed to Fermilab to demonstrate the use of a Helical Cooling Channel (HCC) for future muon colliders and neutrino factories. The HCC for MANX has solenoidal, helical dipole, and helical quadrupole magnetic components which diminish as the beam loses energy as it slows down in a liquid helium absorber inside the magnets. Two superconducting magnet system designs are described which use quite different approaches to providing the needed fields. Additional magnets that provide emittance matching between the HCC and upstream and downstream spectrometers are also described as are the results of G4Beamline simulations of the beam cooling behaviour of the complete magnet and absorber system.

THPMN096 Stopping Muon Beams 2933
  • M. A.C. Cummings, R. P. Johnson
    Muons, Inc, Batavia
  • C. M. Ankenbrandt, K. Yonehara
    Fermilab, Batavia, Illinois
  Funding: Supported in part by DOE SBIR/STTR grant DE-FG02-03ER83722

The study of rare processes using stopping muon beams provides access to new physics that cannot be addressed at energy frontier machines. The flux of muons into a small stopping target is limited by the kinematics of the production process and by stochastic processes in the material used to slow the particles. Innovative muon beam cooling techniques are being applied to the design of stopping muon beams in order to increase the event rates in such experiments. Such intense stopping beams will also aid the development of applications such as muon spin resonance and muon-catalyzed fusion.

THPMN102 A Muon Beam for Cooling Experiments 2948
  • A. Jansson, V. Balbekov, D. R. Broemmelsiek, M. Hu, N. V. Mokhov, K. Yonehara
    Fermilab, Batavia, Illinois
  Funding: Work supported by the US Department of Energy

Within the framework of the Fermilab Muon Collider Task Force, the possibility of developing a dedicated muon test beam for cooling experiments has been investigated. Cooling experiments can be performed in a very low intensity muon beam by tracking single particles through the cooling device. With sufficient muon intensity and large enough cooling decrement, a cooling demonstration experiment may also be performed without resolving single particle trajectories, but rather by measuring the average size and position of the beam. This allows simpler, and thus cheaper, detectors and readout electronics to be used. This paper discusses muon production using 400MeV protons from the linac, decay channel and beamline design, as well as the instrumentation required for such an experiment, in particular as applied to testing the Helical Cooling Channel (HCC) proposed by Muons Inc.

THPMN110 The MANX Muon Cooling Demonstration Experiment 2969
  • K. Yonehara, D. R. Broemmelsiek, M. Hu, A. Jansson, V. D. Shiltsev
    Fermilab, Batavia, Illinois
  • R. J. Abrams, M. A.C. Cummings, R. P. Johnson, S. A. Kahn, T. J. Roberts
    Muons, Inc, Batavia
  Funding: Supported in part by DOE STTR grant DE-FG02-06ER86282

MANX is an experiment to prove that effective six-dimensional (6D) muon beam cooling can be achieved a Helical Cooling Channel (HCC) using ionization-cooling with helical and solenoidal magnets in a novel configuration. The aim is to demonstrate that 6D muon beam cooling is understood well enough to plan intense neutrino factories and high-luminosity muon colliders. The experiment consists of the HCC magnets that envelop a liquid helium energy absorber, upstream and downstream instrumentation to measure the particle or beam parameters before and after cooling, and emittance matching sections between the detectors and the HCC. We describe and compare the experimental configuration for both single particle and beam profile measurement techniques based on G4Beamline simulations.

  • M. BastaniNejad, A. A. Elmustafa
    Old Dominion University, Norfolk, Virginia
  • M. Alsharo'a, P. M. Hanlet, R. P. Johnson, M. Kuchnir, D. J. Newsham
    Muons, Inc, Batavia
  • C. M. Ankenbrandt, A. Moretti, M. Popovic, K. Yonehara
    Fermilab, Batavia, Illinois
  • D. M. Kaplan
    Illinois Institute of Technology, Chicago, Illinois
  Funding: Supported in part by DOE STTR grant DE-FG02-05ER86252

Microscopic images of the surfaces of metallic electrodes used in high-pressure gas-filled 800 MHz RF cavity experiments are used to investigate the mechanism of RF breakdown. The images show evidence for melting and boiling in small regions of ~10 micron diameter on tungsten, molybdenum, and beryllium electrode surfaces. In these experiments, the dense hydrogen gas in the cavity prevents electrons or ions from being accelerated to high enough energy to participate in the breakdown process so that the only important variables are the fields and the metallic surfaces. The distributions of breakdown remnants on the electrode surfaces are compared to the maximum surface gradient E predicted by an ANSYS model of the cavity. The surface local density of spark remnants, presumably the probability of breakdown, shows a power law dependence on the maximum gradient, with E10 for tungsten and molybdenum and E7 for beryllium. This is reminiscent of Fowler-Nordheim behavior of electron emission from a cold cathode, which is explained by the quantum-mechanical penetration of a barrier that is characterized by the work function of the metal.

THPAN106 6D Ionization Cooling Channel with Resonant Dispersion Generation 3477
  • Y. Alexahin, K. Yonehara
    Fermilab, Batavia, Illinois
  • R. B. Palmer
    BNL, Upton, Long Island, New York
  Funding: Work supported by the Universities Research Assoc., Inc., under contract DE-AC02-76CH03000 with the U. S. Dept. of Energy

For muons with preferable for ionization cooling momentum <300MeV/c the longitudinal motion is naturally undamped. In order to provide the longitudinal damping a correlation between muon momentum and transverse position - described in terms of the dispersion function - should be introduced. In the present report we consider the possibility of dispersion generation in a periodic sequence of alternating solenoids (FOFO channel) by choosing the tune in the second passband (i.e. above half-integer per cell) and tilting the solenoids in adjacent cells in the opposite direction. Analytical estimates as well as simulation results for equilibrium emittances and cooling rates are presented.