Field Quality of MBH 11-T Dipoles for HL-LHC and Impact on Beam Dynamic Aperture

For the high-luminosity upgrade of the Large Hadron Collider (HL-LHC), the development of the 11-T Nb
₃
Sn dipole (MBH) is progressing. At present, one double-aperture and five single-aperture short-model magnets have been built and tested. Magnetic measurements have been performed both at ambient and cryogenic temperatures. In addition, a double-aperture short model and the first full-length collared-coil assemblies have been produced and measured at ambient temperature. In this paper, the measurement results collected so far are presented and discussed. The geometrical field multipoles, the iron saturation effects, as well as the effects of persistent currents are summarized. Experimental data are compared with the magnetic calculations using the CERN field computation program ROXIE and discussed in view of the construction of the final magnets. In addition, based on the measured field errors, beam dynamics simulations have been carried out by taking into consideration different scenarios with and without MBH magnets installed in the accelerator.