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This paper presents the main results of the magnetic measurements performed on the available MQXFB quadrupoles at room and cryogenic temperature. The measurement program, carried out during the different stages of the magnet assembly and by using different instruments such as the rotating-coil and stretched-wire systems, allows an early identification of the field errors and a comprehensive characterization of the field quality. A fine tuning of the low-order multipoles is achieved by magnetic shims using iron inserts, which provides a means for improving the field quality of some magnets. The transfer function, the field harmonics, and the effects of superconductor magnetization and iron saturation are reported. In addition, a warm-to-cold extrapolation method is developed for the prediction of the integrated gradient at 1.9 K and nominal current, with an accuracy within 5·10-4, allowing a proper sorting of the magnets at an early stage and before the final cold test. In conclusion, all the MQXFB magnets tested so far meet the field-quality requirements for the HL-LHC, and the adopted measurement and correction strategy has proven to be effective for the series production.
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