The actual detector - a plastic film of polycarbonate foil (about 1 to 10 cm² in size and about 0.1 to 1 mm thick) - is located inside the exposimeter. The air containing radon gas diffuses through the housing into the measuring chamber; however, dust, moisture and radon derivatives are retained. The sufficiently high diffusion resistance also prevents the thoron (220Rn; half-life: approx. 56 seconds) from entering the measuring chamber. The radon then decays in the measuring chamber, emitting alpha particles, into its short-lived derivatives, which are also alpha emitters. The alpha particles leave traces in the film, which are recorded and evaluated in the laboratory.
- Standing open on a table / on a shelf / in a wall unit
- Hanging in the middle of a room (e.g. from a lamp)
- Do not place on the floor Keep at least 25 cm distance from walls
- Do not place at strong heat sources or air currents (draught)
- Maintain a minimum distance of 1.5 m from windows, external doors, air supply valves and radiators
- Keep a minimum distance of 0.5 m from exhaust air valves
- Do not place in damp rooms and inaccessible to small children