Test results for prototypes of the twin aperture dipoles for the LHC insertion region

The Superconducting Magnet Division at Brookhaven National Laboratory (BNL) is building 20 insertion region dipoles of various types for the Large Hadron Collider (LHC) at CERN. These 9.45 m-long, 8 cm aperture magnets use the same coil design as the arc dipoles for the Relativistic Heavy Ion Collider (RHIC) at BNL. The most challenging of these dipoles are the twin aperture magnets. The two apertures are separated by 188 to 234 mm, and the dipole fields in both the apertures point in the same direction. In order to test the design and determine various operating parameters of these magnets, two three m-long prototypes were built and tested at BNL. Tests were done to measure spontaneous quench performance, conductor temperature at quench, coil stress behavior during cool-downs, warm-ups and excitation ramps, and quench protection heater performance. Extensive magnetic field measurements were done with a 3.58-meter long integral coil, as well as a one-meter long coil at the axial center of the magnet. Dynamic effects, such as time decay and snapback at injection, and harmonics due to cable magnetization and eddy currents were studied with a time resolution of 2 s.