Abstract: A chopper for a particle beam comprises an annular guiding element and an element for controlling the intensity of the particle beam. The control element is supported on the guiding element so that at least one point under consideration on the control element can revolve along the circumference of the guiding element. Mounting along a circumference allows for accommodation of considerably higher disturbance torque than mounting on a rotational axle, using the same bearing force. Furthermore, it is possible to dispense with the entire rotational axle, and the control element can be designed, for example, as a ring. This brings about considerable weight savings as compared to chopper wheels according to the prior art, which accordingly enables higher circumferential speeds and therefore higher modulation frequencies for the particle beam, while at the same time increasing operational safety.

Abstract: A chopper for a particle beam comprises an annular guiding element and an element for controlling the intensity of the particle beam. The control element is supported on the guiding element so that at least one point under consideration on the control element can revolve along the circumference of the guiding element. Mounting along a circumference allows for accommodation of considerably higher disturbance torque than mounting on a rotational axle, using the same bearing force. Furthermore, it is possible to dispense with the entire rotational axle, and the control element can be designed, for example, as a ring. This brings about considerable weight savings as compared to chopper wheels according to the prior art, which accordingly enables higher circumferential speeds and therefore higher modulation frequencies for the particle beam, while at the same time increasing operational safety.

Abstract: A process for producing an encapsulated detector operating in an ultra high vacuum (UHV) for gamma (.gamma.) spectroscopy, wherein a detector is placed into a detector chamber portion of a detector containment pot and a lid is placed into the containment pot and both are joined by electron beam welding under vacuum at their top in such a way, that the detector is not exposed to excessive heat and that the vapors generated during welding are condensed before they can reach the detector chamber, whereby a detector capsule capable of maintaining an ultra high vacuum can be produced.

Abstract: In a capsule for a detector operating in an ultra high vacuum suitable as a gamma radiation spectrometer, there is provided a detector chamber in which the detector is mounted and a getter chamber in which a getter element is mounted and the getter chamber is separated from the detector chamber by a thermal protection structure to prevent heating of the detector when the getter element is heated for conditioning. The getter element serves to maintain an ultra high vacuum in the detector chamber over a long period of operation.

Abstract: A tubular filter with porous silicon carbide for filtering particles of soot out of the exhaust gas of a diesel engine is mounted between two holders in a gas duct where one of the holders is spring loaded and the other has a bore that communicates with a bore connecting with the inside of the filter. The holders have surfaces facing the filter that are concavely spherical. The filter ends are provided with matching convexly spherical surfaces and they are directly on the filter ends or on an intermediate piece tightly seated on the filter end. The spherical surfaces are not necessary at the spring loaded holder and for some embodiments the holder can have a convexly spherical surface. The placing of the filter in a duct does not always permit the holders to be exactly opposite each other, but the filter mounting can be accommodated to somewhat offset holders because the gas tightness of the compression joints remain tight when the position of the filter is slightly oblique in the duct.