[en] The total absence of particles is not physically possible so it is more adequate to speak about rarefied atmospheres than vacuum. The ultra-high vacuum is characterized by pressure values below 10^-9 mbar. In ultra-high vacuum the average distance travelled by a molecule between 2 collisions is several thousand kilometers. The ultra-high vacuum is useful for particle accelerators. For the tube of the Large Hadron Collider (LHC) in which the particle beams circulate, the pressure is around 10^-10 - 10^-11 mbar and classical methods like cryogenics or ion pumping are not sufficient. The walls of the vacuum cryogenic enclosures are lined with adsorbing materials called 'getter' that trap molecules. (A.C.)

[en] Full text: We create and launch silicon nanoparticles beneath a high finesse cavity in high vacuum environment. While a particle transits through the intense cavity field the transverse kinetic energy is cooled by a factor of over 30. By detecting the scattered light from the particle we can trace the particles movement in real time. This is a vital step towards quantum coherence experiments with nanoparticles. (author)

No abstract available

[en] Two insertion devices (undulators named U-l and U-2) have been recently installed in Indus-2 synchrotron radiation source, a 2.5 GeV third generation electron storage ring at Raja Ramanna Centre for Advanced Technology, Indore. Four ultra-high vacuum compatible beam position indicators (IDBPIs) for insertion devices have been designed and developed. These IDBPIs have been installed in the long straight sections LS-2 and LS-3 of Indus-2 ring at the upstream side and downstream side of undulators for the precise monitoring of electron beam position. The IDBPIs have been calibrated on a calibration bench setup before their installation in Indus-2 ring. The calibration procedure along with the calibration results has been described in this paper

[en] This paper describes a system set-up at IPR by the SST-1 Vacuum Group to measure the outgassing rates of materials. Design of this system is based on technique to measure differential pressure generated due to gas flow across known conductance

[en] Complete text of publication follows. The vacuum interfaces of inductively coupled plasma mass spectrometers (ICP-MS) are constructed to reduce the atmospheric pressure of the ion source to the high vacuum of the mass analyzer in three stages. The first stage is defined on the upstream end by a sampling cone and on the downstream end by a skimmer cone. Ideally, a supersonic expansion forms downstream from the sampling cone, and the tip of the skimmer cone is placed inside the zone of silence of the supersonic expansion. This arrangement should result in unimpeded ballistic flow of ions through the skimmer cone into the second vacuum stage. Two independent reports indicate that flow through the skimmer cones of typical vacuum interfaces does not match the ideal described above. Niu and Houk observed an abrupt drop in electron density as they passed a Langmuir probe from the first vacuum stage to the second vacuum stage through the skimmer cone (H. Niu and R. S. Houk, Spectrochim. Acta, 49B (1994) 1283-1303). Patterson et al. recorded a bimodal distribution of argon atom velocities at the tip of the skimmer cone that was characteristic of a shock structure at the skimmer tip (J. E. Patterson, B. S. Duersch, and P. B. Farnsworth, Spectrochim. Acta 54 B (1999) 537-544). In this paper we will present measurements of flow efficiency through the skimmer cone derived from fluorescence probes placed 2.5 mm upstream from the tip of the skimmer and 2.5 mm downstream from the skimmer. Ratios of signals recorded simultaneously by the two probes indicate that the density downstream from the tip of the cone is nearly an order of magnitude lower than would be obtained from ideal skimming. The density is strongly dependent on first stage vacuum pressure, even at pressures where simple calculations indicate that the tip of the skimmer cone is well within the zone of silence of the supersonic expansion. In conjunction with the experimental measurements of flow through the skimmer cone, we will present computational models of the flow based on direct simulation Monte Carlo calculations. The computations show the formation of a shock structure at the tip of the skimmer cone and point to design features of the cone that affect the degree of shock formation.

[en] The nitrided ultrathin SiO₂ films using a remote nitrogen plasma source were investigated by high-resolution x-ray photoelectron spectroscopy. At the low nitridation temperature of 500 deg. C, the nitrogen is effectively incorporated in 15 Aa SiO₂ film. The chemical shifts of the N 1s peaks show that the quantity of the second-nearest neighbors of oxygen atoms and N-O bonds influences the difference of the peak shift depending on the nitridation temperature and post-annealing in ultrahigh vacuum. The peak intensity changes of the N 1s peak at the different take-off angles indicate that the nitridation dominantly occurs at the interfacial region as the nitridation temperature increases, which suggests that the highly incorporated nitrogen at the surface region can be accomplished even with a low temperature nitridation process using a remote nitrogen plasma source. The defect formation due to the nitrogen incorporation resulted in a negative shift of the capacitance-voltage curve, and the difference is increased as the nitridation temperature is elevated

[en] The lifetime of the metastable 5d²D_5/2 state has been measured for a single trapped Ba⁺ ion in a Paul trap in Ultra High Vacuum (UHV) in the 10⁻¹⁰ mbar pressure range. A total of 5046 individual periods when the ion was shelved in this state have been recorded. A preliminary value ${\mathrm{\tau <!--\; ??\; -->}}_{D_{5/2}}=26.4(1.7)$ s is obtained through extrapolation to zero residual gas pressure.

[en] This paper explains the works being done to convert an old x-ray machine into a low energy electron beam accelerator. In this project, we replace the x-ray tube from the machine with an electron accelerating tube while maintaining the high voltage power supply of 160 kV. Components involved in this project development are understanding the physics of accelerated particles, designing the ultra high vacuum system of at least 10-6 torr to vacuum the tube, assembling the high voltage supply and electron gun to accelerator tube and installing a thin titanium at the end of the tube as a window for the electrons to escape to atmosphere. Two stages of pumping are needed to meet the vacuum requirement; the first is for rough pumping down to 10^-3 torr and then subsequently switching to the second stage that continues pumping to reach the required level. For the first stage, we use a rotary pump and for the later either a turbo molecular pump or a diffusion pump. Furthermore, it is also essential to design and fabricate a connector with suitable insulation material to connect the high tension (HT) cable from the x-ray machine with the cathode of the accelerating tube. The electrons that escape from the window into atmosphere are collected and measured using a faraday cup meter. We expect to get some initial data from this setup before the seminar and hopefully will present it together with the theoretical calculation and design of the main components. (Author)

No abstract available