CERN, Geneva
IHEP Protvino, Protvino, Moscow Region
TRIUMF, Vancouver
The LHC has two dedicated cleaning insertions: IR3 for momentum cleaning and IR7 for betatron cleaning. The collimation system has been specified and built with tight mechanical tolerances (e.g. jaw flatness ~ 40 μm) and is designed to achieve a high accuracy and reproducibility of the jaw positions. The practically achievable cleaning efficiency of the present Phase-I system depends on the precision of the jaw centering around the beam, the accuracy of the gap size and the jaw parallelism against the beam. The reproducibility and stability of the system is important to avoid the frequent repetition of beam based alignment which is currently a lengthy procedure. Within this paper we describe the method used for the beam based alignment of the LHC collimation system, its achieved accuracy and stability and its performance at 450GeV.
Karlsruhe Institute of Technology (KIT), Karlsruhe
CERN, Geneva
BNG, Würzburg
STFC/RAL, Chilton, Didcot, Oxon
INFN/LNF, Frascati (Roma)
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
Diamond, Oxfordshire
UMAN, Manchester
Rome University La Sapienza, Roma
MAX-lab, Lund
Max-Planck Institute for Metal Research, Stuttgart
One of the still open issues for the development of superconducting insertion devices is the understanding of the beam heat load. With the aim of measuring the beam heat load to a cold bore and the hope to gain a deeper understanding in the beam heat load mechanisms, a cold vacuum chamber for diagnostics is under construction. The following diagnostics will be implemented: i) retarding field analyzers to measure the electron flux, ii) temperature sensors to measure the total heat load, iii) pressure gauges, iv) and mass spectrometers to measure the gas content. The inner vacuum chamber will be removable in order to test different geometries and materials. This will allow the installation of the cryostat in different synchrotron light sources. COLDDIAG will be built to fit in a short straight section at ANKA. A first installation at the synchrotron light source DIAMOND is under discussion. Here we describe the technical design report of this device and the planned measurements with beam.
CERN, Geneva
At the start of the CERN Large Hadron Collider (LHC) 2008-2009 shutdown, all the LHC experimental vacuum chambers were vented to neon atmosphere. They were later pumped down shortly before beam circulation. In parallel, 2.3 km of vacuum beam pipes with NEG coatings were vented to air and re-activated to allow the installation or repair of several components such as roman pots, kickers, collimators, rupture disks and masks and re-activated thereafter. Beside these standard operations, "fast exchanges" of vacuum components and endoscopies inside cryogenic beam vacuum chambers were performed. This paper presents a summary of all the activities held during this period and the achieved vacuum performances.
CERN, Geneva
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
Pressure increases are observed with the first beams circulating in the CERN Large Hadron Collider (LHC) close to some collimators. This paper describes the vacuum performances of the collimators as measured in the laboratory and also the performances obtained in the machine. Based on these observations, estimations of some operational behavior such as pressure increase and NEG reactivation scenario are given.
CERN, Geneva
During the sector 3-4 incident, the two apertures of the 3 km long cryogenic vacuum sectors of the CERN Large Hadron Collider (LHC) were brutally vented to helium. A systematic visual inspection of the beam pipe revealed the presence of soot, metallic debris and super insulation debris. After four month of cleaning, the beam vacuum system was recovered. This paper describes the tools and methodologies developed during this period, the achieved performances and discusses possible upgrades.