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The CERN Large Hadron Collider (LHC) has 54 km of ultra-high vacuum (UHV) beam chambers out of which about 90% are at cryogenic temperature (1.9 K) and the rest at room temperature. During operation, the residual gas density in the beam pipes is dominated by beam induced effect such ion, electron and photon-stimulated gas desorption. Therefore, the computation of gas density profile is of great importance...
The 27km long large hadron collider (LHC), currently under construction at CERN, will collide protons beam at 14TeV in the centre of mass. In the 8 arcs, the superconducting dipoles and quadrupoles of the FODO cells operate with superfluid He at 1.9K. In the 8 long straight sections, the cold bores of the superconducting magnets are held at 1.9 or 4.5K. Thus, in the LHC, ∼75% of the beam tube vacuum...
The cold bore experiment installed in the super proton synchrotron has been used to study the performance of a vacuum system operating at cryogenic temperatures in the presence of a large hadron collider (LHC) type proton beam. The ~2m long cryostat, which can be cooled below 3K, is fitted with an actively cooled beam screen which can be temperature controlled between 5 and 100K. Molecular desorption...
A cryogenic vacuum system has been used to study both the surface pumping of gases and the molecular photodesorption yield from OFE copper in the temperature range from 5 to 300K. The sticking coefficient on a 'bare surface' was found to increase with decreasing temperature of the substrate and below 20K, to be in the range of a few per cent for all gas species studied. The molecular photodesorption...
Two stainless-steel vacuum chambers, after putting them through a usual laboratory ultrahigh vacuum processing, have been exposed to a white synchrotron radiation photon beam, 3.75keV critical energy at DCI. However, no ''in-situ'' bake out was performed on the vessels before the irradiation. The first test chamber was a simple 130mm diameter circular tube 3.6m in length. Beam scrubbing for a photon...
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