圆柱形正比计数管倍增研究

通过分析圆柱形正比计数管内电场强度，运用Diethorn公式得出自制圆柱形正比计数管内倍增发生在距阳极30μm以内区域；其最小工作电压为370~670V，且随阳极和阴极直径增加而升高，但随阴极变化较缓慢。正比计数管阳极丝直径减小导致其附近电场强度增强，工作气压降低可使其平均自由程增大，这些均会增加管内次级电子数而使倍增因子增大。采用细阳极丝、低工作气压既可降低正比计数管最小工作电压，还能优化其放大性能，使其更适合于深空中的辐射剂量测量。

Study of Multiplication in Cylindrical Proportional Counter

Electrical field in cylindrical proportional counter (PC) was analyzed by using Diethorn formula. It can be seen that multiplication in homemade cylindrical PC happens within the range of less than 30 μm from anode. The lowest operating voltage of the PC is 370-670 V, and it increases with the diameter of both anode and cathode, but changes slowly with the latter. A thinner anode can lead to stronger field around itself, and a lower working pressure will lead to larger mean free path. Both of them can improve the multiplication factor due to the generation of more and more secondary electrons in PC. Selecting a thin anode and low working pressure can not only reduce the lowest operating voltage, but also optimize the performance of amplification of PC, which makes it more suitable to measure radiation dose in deep space.