Geiger Mueller Detectors

The essential components of the geiger-mueller detector are its two collecting electrodes: the anode and cathode (the anode is positively charged with respect to the cathode). In most cases, the outer chamber wall serves as the cathode. The potential difference between the anode and cathode is usually in the 800 to 1200 volt range.

A cylinder (often 446 stainless steel) serves as the cathode while a wire (usually tungsten) running along the central axis serves as the anode. The primary application of the side window GM is the measurement of gamma exposure rates. Nevertheless, its wall can be thin enough to permit higher energy betas (>300 keV) to be counted.

The density thickness of a typical thin walled cylindrical GM is 30 mg/cm2. The density thickness (aka aerial density) is a convenient way to describe the thickness of very thin materials it is the product of the material’s density (mg/cc) and its thickness (cm). To measure it, weigh one square centimeter of the material.