2π栅网电离室法用于衰变率绝对测量早有文献报道,它具有探测效率高、能量分辨率高、本底低、操作方便等优点。但作为衰变率绝对测量需进行源的自吸收与源底衬反散射校正。具有一定厚度的平板α源,通常采用熟知的校正因子t/2 R(t为源的厚度、R为α粒子在源中射程)来进行自吸收修正。对含微量物质(t≤1 ug/cm~2)的α源,由于 2π grid ionization chamber method for the absolute measurement of decay rate reported in the literature, it has high detection efficiency, high energy resolution, low background, easy operation and so on. However, as an absolute measure of decay rate, source self-absorption and source backing anti-scatter correction are required. Flat plate sources with a certain thickness are normally self-absorbed using the well-known correction factor t / 2 R (t is the thickness of the source and R is the range of the alpha particles in the source). For a small amount of material (t ≤ 1 ug / cm ~ 2) α source, due to