Miniaturised radiation detection appts - for instantaneous warning of personal exposure incorporating speaker as well as galvanometer

摘要

A miniaturised appts. for detecting personal exposure to radiation incorporates as the sensitive element a quadratic monocrystal of mercuric iodide with two conducting armatures. The armatures are formed by a metal, germanium or palladium deposited by evaporation under vacuum on two plane faces of the crystal, the thickness of the crystal between the armatures being .1 to 50 mm, pref. .5 to 10 mm. The crystal is encapsulated in an insulating substance which is enclosed in an aluminium box. One gold or stainless steel conducting wire connects one of the armatures to the case; another, connected to the other armature, passes through the case, insulated from it. The appts. incorporates a direct-alternating-direct converter to polarise the armatures, applying a direct voltage (50-100 volts) between them, as well as a low voltage source, a signal device and amplifying and oscillatory circuits to feed the signal device in response to electrical perturbations produced by radiation incident on the monocrystal. The signal device is a speaker and a galvanometer is included as well. The appts. is less bulky than a Geiger-Muller counter and gives an instant alarm, not provided by a photographic film.