On March 2024, US magnet MQXFA15 cold test was successfully completed at the BNL Vertical Magnet Test facility. This magnet is the 10th MQXFA magnet meeting HL-LHC requirements. The US contribution to HL-LHC includes 10 LQXFA/B Q1-Q3 cryomodules, each containing two 4.2 m long magnets, for a total of 20 magnets. The achievement on MQXFA15 places the US contribution right in the middle of the path to the final goal.

MQXFA15 achieved acceptance current (16,530 A) with a relatively low number of training quenches, demonstrating improvement in performance following minor and controlled increases in pre-stress applied to the magnet during fabrication. These improvements resulted from lessons learned from the assembly of previous MQXFA magnets and from the MQXFS (short magnets) program at CERN.

AUP continues to move forward with the assembly of LQXFA/B cryomodules. After delivery of the first LQXFA/B-01 cryomodule to CERN in December 2024, AUP is presently assembling LQXFA/B-02, to be destined to the IT string and planned for delivery to CERN in fall of 2024. Cold Masses LMQXFA03 and LMQXFA04 (for the respective cryomodules) are already in advance stages of fabrication at FNAL. MQXFA15 completes the magnets destined to cryo-assembly LQXFA/B-05 and will shortly be shipped from BNL to FNAL.

By Giorgio Apollinari, US HL-LHC AUP project manager

Training curve for MQXFA15. The magnet reached Acceptance Current after 2 training quenches, demonstrating current margin over the Operating Current. The magnet reached Operating Current at 4.5K, demonstrating temperature margin. Ramps represented by a dash-sign did not result in any quench. (Image: FNAL)

AUP Cold Mass and Cryomodule Assembly activities. In the top-left part of the picture, welders are assembling the thermal shields around LMQXFA-02, in preparation for insertion of the Cold Mass into the cryostat (visible on the right) to produce LQXFA/B-02. In the bottom-left part of the picture, LMQXFA-03 is visible, being readied for the capillary tube assemblies. The two metrologists in the top-right part of the picture are aligning two magnets (not visible in the picture) for LMQXFA-4, the 4th Cold Mass for Q1-Q3. (Image: FNAL)