Status of Production of Beam Separation Dipole Magnets for the High-Luminosity LHC Upgrade

Abstract

Beam separation dipole magnets (D1 magnet, MBXF) will be installed on both sides of two interaction points (ATLAS and CMS) for the High-Luminosity Large Hadron Collider upgrade (HL-LHC). High Energy Accelerator Research Organization (KEK) is responsible for delivering one full-scale prototype and six series production cold masses to the HL-LHC project. Three series production magnets (MBXF1, 5, and 2, in order of testing) and the prototype cold mass (LMBXFP1) have been constructed by Hitachi, Ltd. after technological transfer from KEK. Cold powering tests of the series production magnets were conducted at KEK. The quench current reached the ultimate current corresponding to the peak field of 6.0 T and the load line ratio of 83% . MBXF1 and 2 experienced a full thermal cycle and good training memory was confirmed. The results of magnetic field measurements show that the integrated multipole coefficients are reproducible among three series production magnets and controlled as expected from the simulations. A horizontal cold powering test of LMBXFP1 with an LHC cryostat was performed at CERN. Measured multipole coefficients were consistent with the calculation results, suggesting the validity of the magnetic design considering the effect of the ferromagnetic cryostat.