Using a pulsed deflector for extraction of pulsed beams from the TRIUMF cyclotron

In the normal mode of operation, the TRIUMF cyclotron accelerates H^- ions to produce 500 MeV proton beams of 160 μA with 4 nsec pulses separated by 43 nsec. A proposed experiment (μ→e conversion) requires a 500 MeV beam with 100-200 nsec pulses separated by 1-2 μ sec with an average intensity of 200 μA. Two methods have been investigated to achieve this time structure. Both incorporate a pulsed electric deflector and take advantage of extraction by stripping. In the first case, a deflector with a thin septum deflects radially up to six accumulated turns onto a stripping foil in one turn. In the second, a pair of vertically deflecting plates are pulsed at a frequency to excite a coherent vertical growth, and the particles are eventually intercepted by a stripping foil. Under certain conditions extraction occurs in almost perfect synchronism with the driving pulse. Both methods will be described in detail and results of computer simulations will be presented