Analysis of Warm Magnetic Measurements of the First Series-Design Prototypes of the LHC Main Quadrupoles

The room temperature magnetic measurements of the first series-design prototypes of the LHC main quadrupoles are analysed. Data relative to the collared coils and to the assembled cold mass are considered. The averages of the multipoles along the magnet axis are interpreted as the systematic components. The agreement with the nominal design is verified, and possible explanations for discrepancies with regard to the multipole allowed by symmetry are worked out. The standard deviations of the multipoles along the axis are interpreted as the random components. We show that the latter can be interpreted in terms of random movements of up to 25-35 µm of the coil blocks, because of components and assembly tolerances. A good correlation between measurements made on collared coil and the assembled cold mass is found. The influence on field quality of a systematic radial misalignment of the coil conductor is also evaluated.