The window of the GM tube is very thin mica. This mica window is protected by a screen. Some levels of alpha, low energy beta, gamma, and x-rays that cannot penetrate the plastic case or the side of the tube can be sensed through the window.
盖革计数管的窗口是非常薄的云母。这个云母窗口用屏幕保护。一些不能穿透计数管的外壳或侧面的低能量的α、β、γ和x射线,可以通过窗口被检测。