Magnet fabrication for the antiproton accumulator

The Antiproton Accumulator Ring is a unique facility for collecting, storing and concentrating antiprotons into an intense beam by means of a new technique known as stochastic cooling. This process requires very large radial apertures and a maximum of available straight section space. The main magnet system for the ring consists of two types of dipoles with fields of 1.6 and 1.8 T and two types of quadrupoles with a steel length of only 54 cm and horizontal apertures up to 70 cm. All magnets were fabricated from 1.5 mm thick precision-punched steel laminations, the largest of which were 2.49 m × 0.727 m and had to be stacked to follow a curved reference surface. This paper describes: the structural design, the fabrication techniques used both for cores and excitation coils, the difficulties encountered and the means employed to obtain the necessary precision in assembly.