Special injection region quadrupole for the CERN antiproton collector ring

The design and construction of the CERN antiproton collider´s special injection region are summarized. Among 56 quadrupoles, 16 are displaced to participate in the bending field made up of 24 dipoles. Some magnets for antiproton injection and extraction are used also as ring-lattice magnets to store the beam. A shield has been added around the vacuum chamber to minimize the effect of magnetic flux when the injected beam crosses a dipole core. One ring quadrupole with combined functions has a large aperture with a strong field at the edges and acts simultaneously on the injected and circulating beam. Another quadrupole, with combined functions, was designed with two semi-quadrupoles. One belongs to the injection lattice and another to the ring lattice where the circulating and ejected beams pass through it.