• A. Afanasev, R.J. Abrams, C.M. Ankenbrandt, K.B. Beard, R.P. Johnson, T.J. Roberts, C. Y. Yoshikawa
  Muons, Inc, Batavia
• M. Popovic
  Fermilab, Batavia

We study electron-positron in-flight annihilation as a potential source of quasi-monoenergetic photon (or gamma-ray) beams. A high-intensity tunable-energy (1.5 MeV to 15 MeV) gamma source has many potential uses in medical, industrial and security applications. Several electron-positron collision geometries are considered: a) head-on; b) collinear; and c) positron beam incident on a fixed electron target. We analyze advantages of each of the geometries in order to optimize parameters of the generated gamma-ray beams.

• R.J. Abrams, C.M. Ankenbrandt, C. Y. Yoshikawa
  Muons, Inc, Batavia

Positrons produced by electrons impinging on a target cover a broad momentum range. By bending the positrons 180° in a dipole magnetic field the momenta are dispersed according to their momenta along the exit plane of the magnet. A wedge-shaped absorber placed at the exit plane can reduce the momenta accordingly to produce a quasi-monochromatic beam of positrons. Simulation results are presented for 2 to 10 MeV/c quasi-mono-chromatic positrons produced by 75 MeV electrons on a tungsten target.

• C. Y. Yoshikawa, R.J. Abrams, A. Afanasev, C.M. Ankenbrandt, K.B. Beard
  Muons, Inc, Batavia
• D.V. Neuffer
  Fermilab, Batavia

A compact tunable gamma ray source has many potential uses in medical and industrial applications. One novel scheme to produce an intense beam of gammas relies on the ability to create a high flux of positrons. We present various positron production methods that are compatible with this approach for producing the intense beam of gammas.

• C.T. Rogers
  STFC/RAL/ASTeC, Chilton, Didcot, Oxon
• A. Alekou
  Imperial College of Science and Technology, Department of Physics, London
• M. Martini, G. Prior
  CERN, Geneva
• D.V. Neuffer
  Fermilab, Batavia
• D. Stratakis
  BNL, Upton, Long Island, New York
• C. Y. Yoshikawa
  Muons, Inc, Batavia
• M.S. Zisman
  LBNL, Berkeley, California

We discuss alternative designs of the muon capture front end of the Neutrino Factory International Design Study (IDS). In the front end, a proton bunch on a target creates secondary pions that drift into a capture channel, decaying into muons. A sequence of RF cavities forms the resulting muon beams into strings of bunches of differing energies, aligns the bunches to (nearly) equal central energies, and initiates ionization cooling. This design is affected by limitations on accelerating gradients within magnetic fields. The effects of gradient limitations are explored, and mitigation strategies are presented.

• D.V. Neuffer
  Fermilab, Batavia
• M. Martini, G. Prior
  CERN, Geneva
• C.T. Rogers
  STFC/RAL/ASTeC, Chilton, Didcot, Oxon
• C. Y. Yoshikawa
  Muons, Inc, Batavia

We discuss the design of the muon capture front end of a neutrino factory and present studies of variations of its components. In the front end, a proton bunch on a target creates secondary pions that drift into a capture transport channel, decaying into muons. A sequence of rf cavities forms the resulting muon beams into strings of bunches of differing energies, aligns the bunches to (nearly) equal central energies, and initiates ionization cooling. The cooling section uses absorber material (reducing the 3-D muon momenta) alternating with rf cavities (restoring longitudinal momentum) within strong focusing magnetic fields. The design is affected by limitations on accelerating gradients within magnetic fields. The effects of gradient limitations are explored, and mitigation strategies are presented. Variations of the ionization cooling and acceleration scenarios and extensions toward use in a muon collider are discussed.

• C. Y. Yoshikawa, C.M. Ankenbrandt
  Muons, Inc, Batavia
• D.V. Neuffer
  Fermilab, Batavia

Intense muon beams have many potential applications, including neutrino factories and muon colliders. However, muons are produced as tertiary beams, resulting in diffuse phase space distributions. To make useful beams, the muons must be rapidly cooled before they decay. An idea conceived recently for the collection and cooling of muon beams, namely, the use of a Quasi-Isochronous Helical Channel (QIHC) to facilitate capture of muons into RF buckets, has been developed further. The resulting distribution could be cooled quickly and coalesced into a single bunch to optimize the luminosity of a muon collider. After a brief elaboration of the QIHC concept, some recent developments are described.