Abstract: A vacuum diode with a high saturation current density and a rapid response time for the detection of electromagnetic radiation. This diode comprises a grid (6) in the shape of a cylinder and a photo-cathode (4) which extends along the axis (X) of the cylinder. The photo-cathode includes a part of the internal conductor of a coaxial cable (8), the external conductor and the electrically insulating material of the coaxial cable being removed opposite this part, and the grid is electrically connected to the external conductor of this coaxial cable, the internal and external conductors being coaxial. Application to the detection of visible, infra-red, ultra-violet and X radiation.

Abstract: Calorimeter for measuring the energy transported by radiation. This calorimeter comprises an absorbing element able to absorb radiation and having an outer face exposed to the radiation and an inner face, said element undergoing a temperature rise during the interaction with the radiation. This temperature rise is measured by a thermopile. The calorimeter also comprises calibration means constituted by a strip-like resistive deposit in direct contact with the inner face of the absorbing element over at least 50% of the surface thereof. Application to the measurement of the energy transported by electromagnetic radiation or a particle flux.