An Eberline, Model HP 260, “pancake” probe. The probe, which is 25 cm in length, is believed to be a copy of the Ludlum, Model 44-9, alpha, beta and gamma probe (Artifact 2020-024). The Model HP-260 is a sensitive beta detector, featuring a “pancake” GM tube with a thin mica window.
The open window, which is protected by an etched stainless steel screen, permits useful beta sensitivities down to 40 keV. The detector is alpha sensitive above 3 MeV. The thin detector has a 1.4-2.0 mg per square cm thick mica window and is protected by the screen, which is 79 percent open. Mica windows must be used instead of Mylar because Mylar will react with the halogen quench gas. The Geiger-Mueller-based probe has an active window diameter of 5 cm. of 5 The Eberline Company, based in Albuquerque, New Mexico, produces and services a wide range of radiation detection equipment .
