Contribution to the development of the Geiger-Mueller metallic detectors, halogenated with mica windows

In this work, we present the development of a model of a Geiger-Mueller detector that fulfill the commercial and industrial requirements for a national market. The prototype has a cylindrical shape with 37 mm of effective length and a mica window of 1,5 mg/cm2 to 2 mg/cm2 thickness with a useful diameter of 19,8 mm. For the window preparation an special cutting technique was developed. Basically two types of quenching agents, Br2 and Cl2 were studied. We work with treatment of the surface of the cathode through electro polishing and chemical passiveness. Our main objective was to get a Geiger-Mueller detector with an operational plateau over 200 V, working voltage above 600 V and a sensitivity of 320 cps at 1 E-04 Gy/h. (author)