A compact electromagnet for a ″frosted″ polarized proton target

A compact magnet with movable poles for a ″frosted″ polarized proton target 400 mm long and 20 mm across is described. Given the interpole clearance 74 mm, the field in the target's working body is 2.5 T with a nonuniformity of ±1.5×10-4. After the dynamic pumping of polarization and the stabilization of working temperature within the target, the magnet poles move apart to a distance of 25 cm, resulting in a spatial angle of secondary particle extraction of 0.4 sr. As this takes place, the field in the target specimen make up 0.46 T. A fast reversal of target polarization at 10-min intervals is provided by a support, allowing to rotate the magnet about the beam axis within the range of ±180°.