Field quality in Fermilab-built models of quadrupole magnets for the LHC interaction region

Superconducting quadrupole magnets for the interaction regions of the Large Hadron Collider are being developed by the US-LHC Accelerator Project. These 70 mm bore quadrupole magnets are intended to operate in superfluid helium at 1.9 K with a nominal field gradient of 215 T/m. A series of 2 m model magnets has been built and cold tested at Fermilab to optimize their design and construction and to study the performance of the magnets. Field measurements of the 8 model magnets and comparisons with the required field quality are reported in this paper.