A 'hodoscoped' cosmic-ray recorder

A portable Geiger-Muller counter apparatus is described. It includes an eight-channel hodoscope and is designed for use at great depths. Simple transistor circuit techniques are used in conjunction with magnetic tape recording. A discussion is given of the operation of counters from a stabilized voltage supply for greatest possible battery life. The complete equipment consumes about 50 mW and will operate unattended from one set of batteries for longer than a month. The apparatus has been operated successfully in a coal mine at a depth of 1500 ft below the surface.