Model 2401-P Dose Pancake GM Pocket-Size Survey Meter with Dose Filter

he Model 2401-P Dose instrument is a general purpose, self-contained, pocket-sized radiation detection meter designed around the venerable GM pancake detector. A simple switch allows the user to choose among the three decade ranges. Another switch selects between QUIET (click-per-event audio off), NORMAL, BAT CHECK, or OFF. The detector is conveniently packaged inside the instrument, and has a protective screen window. A convenient L-shaped stainless steel handle provides a secure and comfortable grip when using the Model 2401-P as a survey meter. Loosening the knob permits the handle to pivot, allowing the instrument to be easily housed in the included carrying and storage case.

Sliding Dose Equivalent Filter

As many know, the venerable GM pancake has a significant over-response at lower energies between approximately 20 to 160 keV (see red line on graph below). Any dose measurements taken with an unfiltered GM pancake detector would thus have unacceptable errors at these lower energies. To counteract this tendency, a sliding filter is located on the backside of the instrument which can be positioned in view of the GM pancake detector to flatten the response to within 20% referenced to ¹³⁷Cs (662 keV) over an energy range of 20 keV to 1.2 MeV.