A device for detecting and localizing soft gamma and X radiations, comprising an enclosure 10 provided with a window 11 opaque to light and transparent to incident radiations, occupied by a noble gas and provided with electrodes for causing the electrons to drift towards a secondary photon creation space. In said space there reigns an electric field having sufficient value to cause the formation of secondary photons by excitation then de-excitation of the atoms of the noble gas. The secondary photons pass through a transparent window 12 and are converted into photons in the close UV or visible spectrum. The scintillations are localized by PM tubes 23 and 24.

The spatial distribution of mono-energetic x-rays from a point source, is determined by a device which comprises a gas filled enclosure having a flat radiation entrance window. Flat electrodes establish an electrical field of such amplitude that there occurs conversion of said radiation into photo electrons and avalanche electron multiplication resulting in delivery of a burst or pulse of electrons per conversion whose height is an increasing function of the travel path of the electrons avalanche from the location of the conversion event to the planar outlet electrode. A detector located in a second portion of the enclosure receives the pulse of electrons and determines the coordinates and the pulse height of the pulse.

A gas scintillation proportional counter, with a photosensitive layer, is coupled, through a UV transparent window, to a multi-anode proportional chamber filled with a gas mixture (for instance an argon triethylamine-methane mixture) having a large quantum efficiency for the UV photons. When detecting incident photons, there is obtained the good efficiency of photosensitive layers and the satisfactory two-dimensional coordinate localization of multiwire proportional chambers.

In order to measure the values of the electrical charge carried by a surface S of a dielectric sheet, one uses a device consisting of a first electrode or probe (S) facing the surface S, a second electrode applied against the back surface of this sheet, means  to displace laterally the probe with respect to the sheet and means to measure the charges induced on this probe. In addition, by means of acoustical, optical or electrical methods, one subjects the surface S to deformation localized in very small spots p (of an area inferior to the one defining the spatial resolution of the measurement) during very short times and repeatly at frequence high enough and in such a way as to have some overlapping of the spots sequentially deformed.

In order to read-out and reproduce as a visible image the electric charge distribution carried by a dielectric sheet, and formed by the impact of X-rays having traversed a body to be analyzed, one has recourse to a detecting probe out of center with respect to the axis of a head carrying the probe, the head being put in rotation at a high speed (for instance at 6,000 turns/minute), by a small turbine, the axis of the head being displaced relative to the surface of the sheet, parallel to the sheet along two perpendicular directions X and Y in such a way that the probe scans the sheet along a trajectory (T) which has the form of a circle the center of which is subjected to a transverse translation. The read-out can be made very rapidly and leads to a good signal/noise ratio. This allows the use of low irradiation doses for the object to be analyzed. Means can be used to compensate for variations of distance between the probe and the sheet.

The invention relates to a device for reading the quantities of electrical charges borne by a dielectric sheet using a probe scanning the charged surface of the sheet and connected to an electronic circuit adapted to measure the quantities of charges induced on said probe. This electronic circuit comprises an operational transimpedance amplifier and an analog integrator reset to zero periodically by suitable circuitry.

For displaying "electric" images recorded in the form of charges (+) on a dielectric sheet, this sheet is surrounded by two electrodes one of which is transparent, on the face of this latter turned towards the dielectric sheet is provided a layer of an electroluminescent material held spaced at a small distance from said sheet, this sheet is caused to vibrate perpendicularly to itself and the image developed at the level of the layer by the alternating electric charges generated by the vibrating charges is recorded on a photographic support.