Abstract: Multiperiodic linear accelerating structures comprising a succession of cylindrical accelerating cavities C.sub.a having a revolution axis X.sub.1 X.sub.2, and being coupled to each other by cylindrical coupling cavities C.sub.c having the axis X.sub.1 X.sub.2 as revolution axis, which coincides with the mean path of the beam of the particles to be accelerated, the radius R.sub.c of the coupling cavities C.sub.c being substantially equal to the radius R.sub.a of the accelerating cavities C.sub.a. Accelerating and coupling cavities are constituted by a stack of elements easy to machine and braze together.

Abstract: A microwave reflector device of small size, making it possible to deliver a predetermined quantity of the power generated by a high-power microwave generator, comprises a unidirectional element which imposes an appropriate constant load on the generator, and a reflector system constituted by a waveguide D tapped into the output waveguide T of the unidirectional element, said waveguide D being terminated at its free end by a metal plate carrying three quartz rods 10, 11, 12 designed to slide, parallel to the axis of the waveguide D, respectively in three metallic sleeves 13, 14, 15 having a circular shape and dimensioins such that they form cut-off waveguides at the operating frequency of the generator. The free end of each of the sleeves 13, 14, 15 provided with three respective rings 16, 17, 18 of absorber material.

Abstract: An auxiliary collimator is added to the main collimator of a radiotherapy apparatus and comprises a master-container filled with mercury and a localising container containing a block of non absorbent material having a predetermined shape; means being provided for automatically positioning these containers with respect to the main collimator and for allowing the mercury to enter the localising container when once it has taken its working position.

Abstract: A monitoring device transparent to ionizing radiation, designed to measure the orientation, intensity and uniformity of an incident beam, comprises a cylindrical housing forming at least one ionization chamber with one or more ion-collecting electrodes transverse to the housing axis, each electrode being subdivided into a plurality of mutually insulated conductive elements connected to respective amplifiers. The elements of at least one electrode include one or more outer elements surrounding or bracketing one or more inner elements to measure the radiation in a central zone and a peripheral zone. The outputs of the respective amplifiers are additively and subtractively combined in an evaluation circuit.