Streak camera calibration for bunch length measurement at BEPC Ⅱ

摘要

Purpose Streak camera is an important device for bunch length measurement. The errors introduced by streak camera should be considered in measurement. In order to accurately measure bunch length, some streak camera calibrations are studied at BEPC II. Methods In this context, the point spread function, caused by the optical system, is measured at focus mode with both deflections disabled. In the same conditions, the influence of camera gain on measurement is studied. For the dual sweep mode of streak camera, a calibration method using electrical delays is applied to calibrate the beam size result. Results Firstly, a point spread function calibration 1.78 ps of streak camera optical system is obtained with focus mode. Secondly, studying the effect of camera gain on measurement, an optimal camera gain range from 506 to 662 is selected, in which the bunch length measurement error is within 0.5 ps. Thirdly, a dual sweep calibration factor 1.02 is obtained. Conclusions For BEPCII bunch length, there is a little difference before and after the streak camera calibrations. However, for the accurate measurement of ultra-short bunch length, the calibrations are of great significance.