Warm magnetic field measurements of prototype low- beta quadrupole magnet MQXA for the LHC interaction regions

A warm magnetic field measurement system has been designed and constructed for the low- beta quadrupole magnet (MQXA) for the LHC interaction regions. The field quality of the first prototype of MQXA has been evaluated at room temperature with this system. According to the field measurement, we found a quite good correlation between the warm and the cold measurements and good performance of the warm measurement system. The magnet twist angle along the magnet axis was also measured with the system, and the obtained results were consistent with the measurement result of mechanical fiducials on the shell surface of the magnet. (8 refs)