Construction and Test of the Magnets for the AEgIS Experiment

The new AEgIS (Antimatter Experiment: Gravity, Interferometry, Spectroscopy) Experiment has the main goal to measure the Earth's gravitational acceleration of antihydrogen atoms. Two high-homogeneity superconducting 1 T and 5 T solenoids are placed on the same axis and provide the magnetic field required for the cylindrical Penning traps to catch and to accumulate antiprotons delivered by the Antiproton Decelerator of CERN. The solenoids have a free bore of 250 mm and 160 mm respectively and the overall system length is 3 m. The 1 T and 5 T solenoids are equipped with a set of superconducting correction coils charged by individual power supplies. In addition, there is a shielding coil to minimize the stray magnetic field in the measurement area. The solenoids and their sets of correction coils are constructed and tested at CERN. Before system integration the single coils are tested separately in a vertical cryostat. To guarantee smooth precooling of the impregnated coils a small volume of liquid nitrogen is placed inside the solenoid bore without direct thermal contact to the solenoid cold mass. The heat exchange and therefore the cool down rate are controlled by regulating the helium gas pressure in the cryostat. The final magnet control system is used for coil energizing and quench protection.