Abstract: Device to display disintegrations of positrons and comprising at least one pair of scintillators (28) sensitive to gamma radiations and disposed opposite each other, photoelectron multiplier units (30) each associated with one scintillator, devices (34) for the barycentric measurement of the position of scintillations in the scintillators, devices (36) for determining the times of flight of the gamma radiations detected in coincidence in each of the paired scintillators, devices (38) for localizing positron disintegrations, and an image display system (40).

Abstract: An echography device with dynamic focusing and sectorial scanning, comprising a transmitting portion (16) and a receiving portion (18) constituting piezoelectric transducers (4), juxtaposed in a form of a linear bar (2), each transducer (4) being associated with a delay line (26,32), the delays applied when a wave is being received being determined as a function of a reference dependent on the delays when the wave is being retransmitted and stored in a digital memory (34), the said reference being fed into a frequency adjustable oscillator (42) associated with a servo-device (38, 56, 54) through a computer.

Abstract: An apparatus for visualizing a body by detecting the radiation of a tracer contained in this body and consisting of positron emitters, comprising:detection cells situated on each side of the body and permitting detection of the .gamma. particles released by each positron emitter in two opposite directions;means for locating cells arranged in pairs opposite one another, on each side of the body, each pair of opposing cells being located on a straight line passing through a positron emitter;means for coding the location of said pairs of opposing cells;means for memorizing these coded location signals;means for processing these coded and memorized signals;visualization means, controlled by the processing means, for visualizing the image of the body from the different signals coded and memorized, further comprising:means connected to the detection cells for measuring the differences in travel time of the .gamma.

Abstract: A light impact on the photocathode of a photomultiplier is localized by defocusing the beam of emitted photoelectrons, sweeping the surface of the photocathode by means of a localized electric field which is located in the vicinity of the photocathode and by measuring the time which elapses between the instant of commencement of sweeping of the photocathode surface and at least one change of sign of the anode signal.