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Johnson, R. P.

Paper Title Page
MOPP071 Intense Stopping Muon Beams 712
 
  • M. A.C. Cummings, R. J. Abrams, R. P. Johnson, C. Y. Yoshikawa
    Muons, Inc, Batavia
  • C. M. Ankenbrandt, M. A. Martens, D. V. Neuffer, K. Yonehara
    Fermilab, Batavia, Illinois
 
  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.  
MOPP080 Studies of Breakdown in a Pressurized RF Cavity 736
 
  • M. BastaniNejad, A. A. Elmustafa
    Old Dominion University, Norfolk, Virginia
  • M. Alsharo'a, P. M. Hanlet, R. P. Johnson, S. Korenev, M. Kuchnir, D. J. Newsham, R. Sah
    Muons, Inc, Batavia
  • C. M. Ankenbrandt, A. Moretti, M. Popovic, K. Yonehara
    Fermilab, Batavia, Illinois
  • D. M. Kaplan
    Illinois Institute of Technology, Chicago, Illinois
  • D. Li
    LBNL, Berkeley, California
  • D. Rose, C. H. Thoma, D. R. Welch
    Voss Scientific, Albuquerque, New Mexico
 
  Previous studies of RF breakdown in a cavity pressurized with dense hydrogen gas have indicated that breakdown probability is proportional to a high power of the surface electromagnetic field. This behavior is similar to the Fowler-Nordheim description of electron emission from a cold cathode, and it implies that breakdown is a quantum mechanical effect that is characterized by the work function of the cavity metal. We describe our present efforts to measure the distributions of work functions at the nanoscale level on the surfaces of the electrodes used in breakdown studies, and to understand how the RF conditioning process affects them.  
MOPP090 Incorporating RF into a Muon Helical Cooling Channel 760
 
  • S. A. Kahn, M. Alsharo'a, R. P. Johnson
    Muons, Inc, Batavia
  • D. R. Broemmelsiek, A. Jansson, V. Kashikhin, V. S. Kashikhin, A. L. Klebaner, G. F. Kuznetsov, G. V. Romanov, A. V. Shemyakin, D. Sun, K. Yonehara, A. V. Zlobin
    Fermilab, Batavia, Illinois
  • L. Thorndahl
    CERN, Geneva
 
  A helical cooling channel (HCC) consisting of a pressurized gas absorber imbedded in a magnetic channel that provides solenoidal, helical dipole and helical quadrupole fields has shown considerable promise in providing six-dimensional cooling for muon beams. The energy lost by muons traversing the gas absorber needs to be replaced by inserting RF cavities into the lattice. Replacing the substantial muon energy losses using RF cavities with reasonable gradients will require a significant fraction of the channel length be devoted to RF. However, to provide the maximum phase space cooling and minimal muon losses, the helical channel should have a short period and length. In this paper we shall examine three approaches to include RF cavities into the HCC lattice:
  1. Use higher frequency cavities that can be placed inside the magnetic channel,
  2. Interleave cavities between magnetic coil rings, and
  3. Place banks of RF cavities between segments of HCC channels.
Each of these approaches has positive and negative features that need to be evaluated in selecting the proper concept for including RF into the HCC system.
 
MOPP105 Compact, Tunable RF Cavities 802
 
  • M. Popovic, C. M. Ankenbrandt, E. Griffin, A. Moretti, R. E. Tomlin
    Fermilab, Batavia, Illinois
  • M. Alsharo'a, I. B. Enchevich, R. P. Johnson, S. Korenev
    Muons, Inc, Batavia
 
  New developments in the design of fixed-field alternating gradient (FFAG) synchrotrons have sparked interest in their use as rapid-cycling, high intensity accelerators of ions, protons, muons, and electrons. Potential applications include proton drivers for neutron or muon production, rapid muon accelerators, electron accelerators for synchrotron light sources, and medical accelerators of protons and light ions for cancer therapy. Compact RF cavities that tune rapidly over various frequency ranges are needed to provide the acceleration in FFAG lattices. An innovative design of a compact RF cavity that uses orthogonally biased ferrite for fast frequency tuning and liquid dielectric to adjust the frequency range is being developed using physical prototypes and computer models.  
TUPP141 Electron Accelerators for Cleaning Flue Gases and for Oil Liquefaction 1848
 
  • S. Korenev, R. P. Johnson
    Muons, Inc, Batavia
 
  High-power electron beams can be used to reduce the environmental impact of coal and oil-fired power generating plants by removing harmful materials from flue gases. This technology has been tested in the laboratory and at smaller industrial levels, but to make it economically attractive, the accelerator costs must be reduced and the efficiency must be increased for removing toxic components in low concentrations. We propose a simple electron accelerator with a wide beam to reduce costs. To remove toxic materials we propose a plasma reactor for desulfurization and selective catalytic reduction. The designs of 0.5 to 1.0 MeV accelerators with 20 to 100 kW average power are considered, along with the design of a plasma reactor for flue gas treatment. The design of a pilot facility for the oil industry is also presented.  
WEPD013 Four-Coil Superconducting Helical Solenoid Model for Muon Beam Cooling 2431
 
  • V. S. Kashikhin, N. Andreev, A. N. Didenko, V. Kashikhin, M. J. Lamm, A. V. Makarov, K. Yonehara, A. V. Zlobin
    Fermilab, Batavia, Illinois
  • R. P. Johnson, S. A. Kahn
    Muons, Inc, Batavia
 
  Novel configurations of superconducting magnets for helical muon beam cooling channels and demonstration experiments are being designed at Fermilab. The magnet system for helical cooling channels has to generate longitudinal solenoidal and transverse helical dipole and helical quadrupole fields. This paper discusses the Helical Solenoid model design and manufacturing of a 0.6 m diameter, 4-coil solenoid prototype to prove the design concept, fabrication technology, and the magnet system performance. Results of magnetic and mechanical designs with the 3D analysis by TOSCA, ANSYS and COMSOL will be presented. The model quench performance and the test setup in the FNAL Vertical Magnet Test Facility cryostat will be discussed.  
WEPD014 Magnets for the MANX 6-D Muon Cooling Demonstration Experiment 2434
 
  • V. S. Kashikhin, N. Andreev, V. Kashikhin, M. J. Lamm, K. Yonehara, A. V. Zlobin
    Fermilab, Batavia, Illinois
  • M. Alsharo'a, R. P. Johnson, S. A. Kahn, T. J. Roberts
    Muons, Inc, Batavia
 
  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 muon beam emittance reduction 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 the liquid helium absorber inside the magnet. The proposed magnet system design is comprised of coil rings positioned along a helical path, which will provide the desired solenoidal and helical dipole and quadrupole fields. Additional magnets that provide emittance matching between the HCC and the upstream and downstream spectrometers are also described. The results of a G4Beamline simulation of the beam cooling behavior of the magnet and absorber system will be presented.  
WEPD015 Design Studies of Magnet Systems for Muon Helical Cooling Channels 2437
 
  • V. Kashikhin, V. S. Kashikhin, M. J. Lamm, M. L. Lopes, A. V. Zlobin
    Fermilab, Batavia, Illinois
  • M. Alsharo'a, R. P. Johnson, S. A. Kahn
    Muons, Inc, Batavia
 
  Helical cooling channels consisting of a magnet system with superimposed solenoid, helical dipole and quadrupole fields, and a pressurized gas absorber in the aperture, promise high efficiency in providing 6D muon beam cooling for a future Muon Collider and some other applications. Two alternative designs of the magnet system for the helical cooling channel are being investigated at the present time. The first one is based on a straight, large aperture solenoid with helical dipole and quadrupole coils. The other one is based on a spiral solenoid which generates the main solenoid field and the helical dipole and quadrupole components. Both concepts have been developed and compared for the MANX experiment. In this paper we continue design studies and comparison of these two concepts for the high field sections of a helical cooling channel. The results of magnetic and mechanical analysis as well as the superconductor choice and specifications will be presented and discussed.  
WEPD022 High Field Superconductor for Muon Cooling 2455
 
  • J. Schwartz
    NHMFL, Tallahassee, Florida
  • R. P. Johnson, S. A. Kahn, M. Kuchnir
    Muons, Inc, Batavia
 
  High temperature superconductors (HTS) have been shown to carry significant current density in the presence of extremely high magnetic fields when operated at low temperature. The successful design of magnets needed for high energy physics applications using such high field superconductor (HFS) depends critically on the detailed wire or tape parameters which are still under development and not yet well-defined. In the project reported here, we are developing HFS for accelerator use by concentrating on the design of an innovative magnet that will have a useful role in muon beam cooling. Measurements of available materials and a conceptual design of a high field solenoid using YBCO HFS conductor are being analyzed with the goal of providing useful guidance to superconductor manufacturers for materials well suited to accelerator applications.  
WEPD023 Multi-purpose Fiber Optic Sensors for HTS Magnets 2458
 
  • J. Schwartz
    NHMFL, Tallahassee, Florida
  • R. P. Johnson, S. A. Kahn, M. Kuchnir
    Muons, Inc, Batavia
 
  Magnets using new high temperature superconductor (HTS) materials are showing great promise for high magnetic field and/or radiation environment applications such as particle accelerators, NMR, and the plasma-confinement systems for fusion reactors. The development and operation of these magnets is limited, however, because appropriate sensors and diagnostic systems are not yet available to monitor the manufacturing and operational processes that dictate success. Optical fibers are being developed to be imbedded within the HTS magnets to monitor strain, temperature and irradiation, and to detect quenches. In the case of Bi2212, the fiber will be used as a heat treatment process monitor to ensure that the entire magnet has reached thermal equilibrium. Real-time measurements will aid the development of high-field magnets that are subject to large Lorentz forces and allow the effective detection of quenches so that the stored energy of operating magnets can be extracted and/or dissipated without damaging the magnet.  
WEPP028 Flexible Momentum Compaction Return Arcs for RLAs 2578
 
  • D. Trbojevic
    BNL, Upton, Long Island, New York
  • S. A. Bogacz
    Jefferson Lab, Newport News, Virginia
  • R. P. Johnson
    Muons, Inc, Batavia
  • M. Popovic
    Fermilab, Batavia, Illinois
 
  Neutrino Factories and Muon Colliders require rapid acceleration of short-lived muons to multi-GeV and TeV energies. A Recirculating Linear Accelerator (RLA) that uses a single Linac and teardrop return arcs can provide exceptionally fast and economical acceleration to the extent that the focusing range of the RLA quadrupoles allows each muon to pass several times through each high-gradient cavity and the cost of the return arcs is appropriate. Flexible Momentum Compaction (FMC) lattice designs for the teardrop return arcs provide sufficient momentum acceptance to allow multiple passes of each sign of muon in one string of magnets to improve cost-effectiveness.  
WEPP048 Recirculating Linear Muon Accelerator with Ramped Quadrupoles 2629
 
  • S. A. Bogacz
    Jefferson Lab, Newport News, Virginia
  • R. P. Johnson
    Muons, Inc, Batavia
 
  Neutrino Factories and Muon Colliders require rapid acceleration of short-lived muons to multi-GeV and TeV energies. A Recirculating Linear Accelerator (RLA) that uses a single Linac and teardrop return arcs can provide exceptionally fast and economical acceleration to the extent that the focusing range of the RLA quadrupoles allows each muon to pass several times through each high-gradient cavity. A new concept of rapidly changing the strength of the RLA focusing quadrupoles as the muons gain energy is being developed to increase the number of passes that each muon will make in the RF cavities, leading to greater cost effectiveness. We are developing the optics and technical requirements for RLA designs, using RF cavities capable of simultaneous acceleration of both μ+ and μ- species, with pulsed Linac quadrupoles to allow the maximum number of passes.

Supported in part by DOE STTR grant DE-FG02-05ER86253

 
WEPP123 Isochronous Pion Decay Channel for Enhanced Muon Capture 2785
 
  • C. Y. Yoshikawa, C. M. Ankenbrandt, D. V. Neuffer, M. Popovic, K. Yonehara
    Fermilab, Batavia, Illinois
  • R. J. Abrams, M. A.C. Cummings, R. P. Johnson
    Muons, Inc, Batavia
  • Y. S. Derbenev
    Jefferson Lab, Newport News, Virginia
 
  Intense muon beams have many potential applications, including neutrino factories and muon colliders. However, muons are produced in tertiary beams into a diffuse phase space. To make useful beams, the muons must be rapidly cooled before they decay. A promising new concept for the collection and cooling of muon beams is being investigated, namely, the use of a nearly Isochronous Helical Transport Channel (IHTC) to facilitate capture of muons into RF bunches. Such a distribution could be cooled quickly and coalesced into a single bunch to optimize the luminosity of a muon collider. We describe the IHTC and provide simulations demonstrating isochronicity, even in the absence of RF and absorber.  
WEPP147 Aberration-free Muon Transport Line for Extreme Ionization Cooling: a Study of Epicyclic Helical Channel 2833
 
  • A. Afanasev, R. P. Johnson
    Muons, Inc, Batavia
  • Y. S. Derbenev
    Jefferson Lab, Newport News, Virginia
 
  Once the normalized transverse emittances of a muon beam have been cooled to some hundreds of microns, new techniques such as Parametric-resonance Ionization Cooling and Reverse Emittance Exchange can be used to focus the beam very tightly on beryllium energy absorbers for further transverse emittance reduction. The transport lines for these techniques have stringent requirements for the betatron tunes so that resonance conditions are properly controlled and for the dispersion function so that the longitudinal emittance can be controlled by emittance exchange using wedge-shaped absorbers. The extreme angular divergence of the beam at the absorbers implies large beam extension between the absorbers such that these techniques are very sensitive to chromatic and spherical aberrations. In this work we describe general and specific solutions to the problem of compensating these aberrations for these new muon cooling channels.  
WEPP149 Advances in Parametric-resonance Ionization Cooling 2838
 
  • Y. S. Derbenev
    Jefferson Lab, Newport News, Virginia
  • R. P. Johnson
    Muons, Inc, Batavia
 
  Parametric-resonance ionization cooling (PIC) is a muon-cooling technique that is useful for low-emittance muon colliders. This method requires a well-tuned focusing channel that is free of chromatic and spherical aberrations. The dispersion function of the channel must be large where the correction magnets are placed for aberration control but small and non-zero where the ionization cooling beryllium wedges are located to provide emittance exchange to maintain small momentum spread. In order to be of practical use in a muon collider, it also necessary that the focusing channel be as short as possible to minimize muon loss due to decay. A compact PIC focusing channel is described in which new magnet concepts are used to generate the required lattice functions.  
WEPP153 Status of the MANX Muon Cooling Experiment 2844
 
  • K. Yonehara, D. R. Broemmelsiek, M. Hu, A. Jansson, V. Kashikhin, V. S. Kashikhin, M. J. Lamm, M. L. Lopes, V. D. Shiltsev, V. Yarba, M. Yu, A. V. Zlobin
    Fermilab, Batavia, Illinois
  • R. J. Abrams, M. A.C. Cummings, R. P. Johnson, S. A. Kahn, T. J. Roberts
    Muons, Inc, Batavia
 
  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. Studies are presented of the effects of detector resolution and magnetic field errors on the beam cooling measurements.  
THYG03 Ionization Cooling and Muon Colliders 2917
 
  • R. P. Johnson
    Muons, Inc, Batavia
 
  Recent developments in the field of muon beam cooling are reviewed. A view of the impact of new cooling concepts on the overall design of muon colliders is included, as are the prospects for the experimental verification of the required muon beam cooling concepts and technology.  
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