正电子产生靶上初级电子束半径的最小化研究

Minimization of Primary Electron Beam Radius at the Positron Production Target

为获得尽可能高的正电子 (e+)产额 ,严格控制初级电子 (e- )束在e+产生靶上的束半径是至关重要的 .首先分析了使e- 束半径增大的各因素和对这些因素的制约 ;然后以北京正负电子对撞机 (BEPC)的正电子源为例 ,给出了束半径的实测值和计算值的比较 ,以具体说明这些因素的影响 ;最后讨论了北京正负电子对撞机二期工程 (BEPC Ⅱ )的相应优化设计研究 ,提出了获得靶上最小束半径的若干途径 .

To have a high positron yield,it is extremely important to minimize the primary electron beam radius at the positron production target. Various effects on electron beam blow-up have been analyzed.By comparing the measured beam radius with simulation,result at current BEPC positron source,some concrete effects on beam blow-up have been described. A design study on minimizing the electron beam radius at BEPC-Ⅱ positron source is given,and the ways to reach this goal have been summarized. = =