Dosimetry by optical fibers

The Cea-Leti continues to perfect a prototype system to measure the radioactivity by optical fiber captor, developed in the frame of a collaboration with Cogema, whom one of the objectives is the operational dosimetry of extremities. This experimental device, developed by the Dein, uses a micro detector (diameter 200 μ m) with luminescence optically stimulated (O.S.L.) placed at the extremity of an off-centring optical fiber (40 m for the actual prototype). The detector material is a doped alkaline-earth sulfate, developed by the University of Montpellier. It shows the property to restore the image of absorbed dose under the shape of a visible luminescence when it is submitted to a stimulation in infrared radiation. In the prototype, this stimulation is given by a laser diode coupled to the fiber. Different detector materials have been tested, two have been kept for the prototype development: MgS and CaS. (N.C.)