Training Evaluation of Separation Dipoles in HL-LHC

A series production of beam separation dipole, MBXF, is underway toward the High-Luminosity Large Hadron Collider upgrade (HL-LHC). So far, High Energy Accelerator Research Organization (KEK) have tested 4 series magnets in our own vertical cryostat, and their quench training performances have been successfully evaluated. The results show different training behaviors, and particularly MBXF3 has a slower training rate even after the thermal cycle (TC). Quench-antenna (QA) signals for such the magnet shows a prominent oscillatory pattern due to mechanical disturbance. In order to understand origin of the different training behaviors, a new data-acquisition system has been introduced to detect QA activities during powering the magnet. The system was first demonstrated in the second cooldown (CD) of MBXF5 (Apr.- May '25), and the training evolution became clearly visible: Mechanical activities cease with each training cycle while appearance of the activities was confirmed after TC indicating loss of the training memory. We expect that this new detection tool can help to understand the reason of the different training rate, and thus it will be used for rest of the MBXF tests.