부산대학교 도서관

We report the test results of the first series beam separation dipole, MBXF1, for the HL-LHC project. The magnet has a full length of 7 m and is designed to generate a field integral of 35 T $\cdot$ m at a nominal operating current ($I_\text{nominal}$) of 12.11 kA. The cold test is performed at the test facility in High Energy Accelerator Research Organization (KEK) using a 9-m deep vertical cryostat. The test consists of two test cycles with one thermal cycle. In each of the test cycles MBXF1 is energized in superfluid helium at 1.9 K and subjected to a series of quench training and magnetic field evaluation. The test shows that the magnet has a good training performance as it reaches $I_\text{nominal}$ with two quenches and an ultimate operating current ($I_\text{ultimate}$) of 13.231 kA with seven quenches. Furthermore we observe no quench during the training of the second test cycle, indicating MBXF1 has a good training memory. Magnetic measurements of MBXF1 show that the discrepancy between the measured and computed harmonics at the magnetic center is 3.9 units for normal sextupole and less than 0.5 units for the other allowed-normal multipoles. Finally sextupole integral ($\bar{b}_{3}$) and decapole integral ($\bar{b}_{5}$), which are major systematic field errors in MBXF, respectively are estimated to be 2.0 units and 1.7 units for an actual environmental condition with ferromagnetic materials in the LHC accelerator tunnel.