Superconducting Quadrupole Doublet for the Los Alamos Meson Physics Facility

A superconducting quadrupole doublet for beam focusing has been operated with a 30-kG field at the center of the 30-cm-long straight section of the magnets and a 3-kG/cm field gradient. The magnets used twisted multifilament Nb–Ti superconductor imbedded in a Cu matrix of 0.050-in. diameter and operate at currents up to 500 A. Each magnet is equipped with a persistent mode superconducting switch. The room-temperature beam aperture of the magnet-Dewar system is 15 cm. The focal length of the magnet pair is about 1 m for 500-MeV pions. The magnets are mounted in a Dewar with thermally compensated supports to minimize motion upon cooling and a soft iron shield reduces external fields to less than 60 G.