An Axi-Symmetric High Flux Muon Channel

This paper reports the results of a design study of an axi-symmetric high flux muon channel which consists of three coaxial coils. A primary beam strikes a thick production target located on the axis near the midplane of the first coil. Annular slits are located between the first and second coil to define the range of take-off angles relative to the axis and the momentum range of the secondary particles that are accepted. The accepted particles spiral in the axial magnetic field and return to the axis to strike a degrader located near the midplane of the second coil. The muon beam leaving the degrader has its momentum range separated from the momentum range of the electrons and pions leaving the degrader. Annular slits are placed between the second and third coils to transmit the muons and stop the pions and electrons. A beam spot suitable for experiments with stopping muons is produced downstream of the third coil. A central shielding plug and a spiral baffle stop neutrons and secondary particles of the opposite sign. Such a system will have a peak solid angle of acceptance off the production target ¿ l sr and will accept a momentum range > ± 3%. With a suitably chosen degrader material, the channel can alternatively produce a pure pion beam. A fourth coil can be included in the channel to produce a volume of uniform field suitable for the operation of a time projection chamber.