affects the accuracy of ion chambers. The chamber's internal volume must be kept completely dry, and the vented type uses a desiccant to help with this. Because of the very low currents generated, any stray leakage current must be kept to a minimum in order to preserve accuracy. Invisible hygroscopic moisture on the surface of cable dielectrics and connectors can be sufficient to cause a leakage current which will swamp any radiation-induced ion current. This requires scrupulous cleaning of the chamber, its terminations and cables, and subsequent drying in an oven. "Guard rings" are generally used as a design feature on higher voltage tubes to reduce leakage through or along the surface of tube connection insulators, which can require a resistance in the order of 1013 Ω. For industrial applications with remote electronics, the ion chamber is housed in a separate enclosure which provides mechanical protection and contains a desiccant to remove moisture which could affect the termination resistance. In installations where the chamber is a long distance from the measuring electronics, readings can be affected by external electromagnetic radiation acting on the cable. To overcome this a local converter module is often used to translate the very low ion chamber currents to a pulse train or data signal related to the incident radiation. These are immune to electromagnetic effects. Applications Nuclear industry Ionization chambers are widely used in the nuclear industry as they provide an output that is proportional to radiation dose They find wide use in situations where a constant high dose rate is being measured as they have a greater operating lifetime than standard Geiger–Müller tubes, which suffer from gas break down and are generally limited to a life of about 1011 count events. Additionally, the Geiger–Müller tube cannot operate above about 104 counts per second, due to dead-time effects, whereas there is no similar limitation on the ion chamber. Smoke detectors The ionization chamber has found wide and beneficial use in smoke detectors. In an ionisation type smoke detector, ambient air is allowed to freely enter the ionization chamber. The chamber contains a small amount of americium-241, which is an emitter of alpha particles which produce a constant ion current. If smoke enters the detector, it disrupts this current because ions strike smoke particles and are neutralized. This drop in current triggers the alarm. The detector also has a reference chamber which is sealed but is