A technique for reducing magnetic fields at an implant location is disclosed. In one particular exemplary embodiment, the technique may be realized as an apparatus and method for reducing magnetic fields at an implant location. The apparatus and method may comprise a corrector-bar assembly comprising a set of magnetic core members, a plurality of coils distributed along the set of magnetic core members, and connecting elements to connect ends of the set of magnetic core members with each other to form a rectangular corrector-bar configuration. The corrector-bar assembly may be positioned at an exit region of a magnetic deflector to improve uniformity of a ribbon beam having a plurality of beamlets exiting from the magnetic deflector and the rectangular corrector-bar configuration may provide a desired magnetic field clamping action.