Calibration method for electrode gains in an axially symmetric stripline BPM

The four electrodes in the stripline beam position monitor （BPM） for Hefei Light Source （HLS II） storage ring are of axially symmetric type. We have derived a new calibration method of electrode gains for this type stripline BPM. The gain fit error of different data grids was analyzed, and the ±5 mm by ±5 mm grid is the best. The electrode gains of two stripline BPMs （HLS II SR-BD-STLB 1 and HLS II SR-BD-STLB2） were obtained based on offline calibrated data. The results show that data after fitting gains are improved, with the electrode gains being between 0.94 and 1.15.