Bending Magnets for the CBA Beam Transport Line

The beam transport line from the AGS to CBA requires 68 large bending magnets, consisting of pure dipoles and two types of combined function gradient magnets. All three types were designed with the magnetic field calculation program POISSON, using the same exterior dimensions and coil package. The design goal of ± 1% momentum acceptance for the transport line required a wide horizontal aperture, with a much smaller vertical aperture for economy. Two prototypes of one gradient magnet were built, and a facility constructed to measure them and the later production magnets. Measurements were done using both a long coil and a point coil (Rawson-Lush gaussmeter). Preliminary results show ΔB/B < 0.2 × 10
^-3
, ΔG/G < 0.3 × 10
^-2
, and ΔB
₂
/B < 0.3 × 10
^-4
cm
^-2
over the beam aperture. Due to end effects, the actual gradient differs from the design gradient by 1%, which has been compensated for in the beam line design.