北京慢正电子强束流性能研究

Performance study of the Beijing Intense Slow Positron Beam

采用电子束流以及脉冲慢正电子束流对系统进行了调试,对束流系统的性能参数进行了测定和研究。实验结果表明,系统对于模拟电子的传输效率高于98%,电子束斑直径小于5mm。在目前加速器短脉冲的运行模式下,脉冲慢正电子束流的强度达到了105/s以上,IP成像板束流沉积形貌直径小于15mm,脉冲慢正电子束流微分能谱半高宽(FWHM)约为10eV;;在高于3×10?Pa的超高真空中,慢正电子在直流化管道内7存贮40ms后,束流强度减弱到原来的50%。系统各项性能运行参数达到了设计要求。

A slow positron beam based on the Beijing Electron-Positron Collider (BEPC) has been constructed and tested. In this paper, transmission efficiency and other performance parameters of the system are measured by a series of experiments on the pulsed slow positron beam. Results show that the transmission efficiency of the transfer system is above 98% and the size of pulsed slow positron beam’s image got by the IP is less than 15 mm. At the same time, the energy spread of the pulsed slow positron beam is about 10 eV (FWHM). The pulsed beam intensity is about 106 slow positrons/s when BEPC is running under the short-pulse mode. It is also shown that the intensity would be reduced to half of initial value after storing 40 ms at 3×10? Pa vacuum level. 7