Since 1973 X-ray position sensitive detectors (P.S.D.) have been employed for stress analysis. The first models, based on the gas flow of Ar-CH4, were composed of a quartz fiber anode (20 um diameter), coated by a thin carbon layer. From 1975 the gas filling has become permanent. Hence the use of fiber P.S.D. (F-P.S.D.) was made easier; nevertheless, two important inconveniences remained. On the one hand, an intensive X-ray beam could destroy rapidly and locally the carbon film, which makes the detector malfunction; on the other hand, the pulse height analysis (P.H.A.), carried out in 1976, has proved to be ineffectual because of the design of the F-P.S.D. itself: its fiber impedance does not remain constant. Thus the appearnace, in 1979, of a new P.S.D. with a metallic wire (W-P.S.D.) presented a significant advantage (see Fig. 1). The anode—made of tungsten or molybdenum Gilded--can resist intensive X-ray beams perfectly. Hence the life of the detector is only limited by a possible ionization of the filling gas, which approximately corresponds to 1012 counts. A gas refilling--which will be provided in the standard equipment--allows us to use the detector again.