The Variable Energy Polarized Proton Beam at TRIUMF

A polarized H- current of 1 ¿A has been achieved within a normalized emittance of 0.3¿ mm-mrad from a Lamb-shift type source. 80% of the beam is routinely transported at 300 keV along the 45 m long electrostatic injection line to the cyclotron, where 200 nA can be accelerated to 500 MeV and extracted. A Wien filter, located near the entrance of the injection line, is used to compensate for the precession resulting from the cyclotron´s fringe field and to align the spin vertically. Depolarization along the line has been calculated to be less than a few per cent. The polarization, enhanced with a diabatic zero crossing in the source, is approximately 80%; however, a slight loss in polarization has been measured in the cyclotron between 200 and 500 MeV.