[en] The principles are described of the activity of expansion and diffusion cloud chambers. The possibilities are described of the determination of the properties of charged particles using cloud chambers. (M.D.)

No abstract available

[en] The stunning invention of the Wilson chamber in 1911 stayed almost ignored by the physicist community for more than a decade although it permitted the visualization of the track of an alpha particle as soon as 1911. The detection principle is based on the expansion of a saturated vapor that allows the visualization of a ionizing particle motion through the formation of droplets around the ions created all along the particle path. The original device was too slow (only one expansion per minute) to be used for the detection of rare events unless to operate it for months or years. A decisive step was made in the beginning of the twenties by the Japanese physicist Takeo Shimizu, working at the Cavendish Laboratory. He managed to automate the Wilson chamber and to equip it with 2 mirrors and a camera. This new generation allowed 5 expansion per second and the knowledge of the particle track orientation in space thanks to a simultaneous photography following 2 perpendicular directions. A rate of 4 shots a minute was achieved. The Wilson chamber was constantly improved during its 30 years long career and was only supplanted by the bubble chamber in the fifties. (A.C.)

[en] In a jet pump for a nuclear reactor a slip joint is provided between the mixer and diffuser sections thereof to facilitate jet pump maintenance and to allow thermal expansion. To limit leakage flow through the slip joint to a rate below that which causes unacceptable flow induced vibration of the pump, there is provided a labyrinth seal for the slip joint in the form of a series of flow expansion chambers formed by a series of spaced grooves in the annulus of the slip joint

[en] The author presents a short description of the operational features of cloud chambers and their application in experiments. Details, illustrations, and references to the vast amount of research publications in the various fields are given. (Auth.)

[en] This article draws the story of the Wilson chamber. In the second half of the 19. century, a general trend among scientists in Great-Britain was still the observation and the imitation of nature, this romantic approach was launched by Goethe 50 years before. In 1895, Wilson as a young physicist tried to reproduce fog in laboratory. His challenge was to reduce the role of dust particles in the Aitken method: the expansion of wet-saturated air loaded with dust particles creates fog. In 1896, at the Cavendish laboratory, he discovered that ions could be very efficient 'dust particles' to condensate vapor and in 1898 he wrote that the expansion method is probably one of the most sensitive method to detect radiation emitted by radioactive materials. The Wilson chamber got a full success only from the twenties and was intensively used for 30 years in particles and nuclear physics laboratories. This detector allowed the experimental discovery of the positron, the muon and strange particles. (A.C.)

[en] Formation of atmospheric aerosol particles and cloud droplets strongly depends on nucleation of nanoclusters. However, homogeneous as well as heterogeneous nucleation are still among the least understood phenomena in aerosol science. New particle formation generally proceeds via critical molecular clusters. The heterogeneous nucleation theorem allows to determine critical cluster sizes directly from experimental observables. By heterogeneous nucleation experiments in an expansion chamber system we were bridging the range from molecular clusters to nanoparticles clearly observing a charge sign effect. Recently we were able to activate single seed molecules well below the Kelvin prediction. This unexpected behaviour has been explained by quantitative determination of the molecular content of critical clusters. Thus the particle size range for Condensation Particle Counters is now considerably extended down to about 1 nm. CPCs are key instruments for observation of cluster formation under near atmospheric conditions in ongoing model experiments at CERN. (author)

[en] Fuel pins irradiated to 25, 50 and 100 GWd/t have been punctured using a single punch unit and the gases collected were analyzed using a quadrupole mass spectrometer. It was noticed that the isotopic composition of the gases collected from the two ends of a fuel pin was different. It is necessary to puncture both ends of the pin simultaneously

[en] A radio frequency (RF) ion source was developed for neutral beam injector in Institute of Plasma Physics, Chinese Academy of Sciences (ASIPP). A cylindrical driver based RF plasma source was tested and optimized for long pulse operation. Recently, the plasma source achieved 1000 s stable plasma discharge with RF power of 35 kW and source pressure of 0.7 Pa for the first time. The heat loading on each of driver components such as the Faraday shield (FS), RF coil and expansion chamber was measured by the water flow calorimeter system. The experiment results showed that FS is the component with highest heat loading and the heat loading on FS was about 65.8% of total heat loading on source. The details of the long pulse operation of RF plasma source are presented in this paper. (letter)

No abstract available