• V. Baglin, G. Bregliozzi, J.M. Jimenez
  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.

• V. Baglin, G. Bregliozzi, J.M. Jimenez
  CERN, Geneva
• J. Kamiya
  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.