Beam Coupling Impedance Measurement and Mitigation for a TOTEM Roman Pot

The longitudinal and transverse beam coupling impedance of the first final TOTEM Roman Pot unit has been measured in the laboratory with the wire method. For the evaluation of transverse impedance the wire position has been kept constant, and the insertions of the RP were moved asymmetrically. With the original configuration of the RP, resonances with fairly high Q values were observed. In order to mitigate this problem, RF-absorbing ferrite plates were mounted in appropriate locations. As a result, all resonances were sufficiently damped to meet the stringent LHC beam coupling impedance requirements.Comment: 3 pages, 8 figures, proceedings of the 11th European Particle Accelerator Conference (EPAC08), Genova, Italy, June 200

Facing new safety-challenges in a large particle accelerator experiment at CERN

An upgraded safety concept for CMS has been adapted to the size of the project and its organisational challenges under today's budgetary constraints, as well as to the increasing levels of risk. Strong magnetic fields and high radiation levels, including neutrons, pose additional hazards to materials, to operators, to maintenance and to ultimate deposit of activated materials. CMS also fits the insurer's risk-description for modern facilities, i.e. characterised by "higher energy density, more combustible materials and unattended operation". The regulatory environment, consisting essentially of CERN's autonomous regulations as well as of those of its host countries, also need to be satisfied with much attention. To face this challenge, seven distinct safety management tools have been identified, which are described in some detail, namely clear safety objectives, documented safety requirements, open items list, safety ( and design)reviews, safety risk analysis, enforcement of compliance and quality management. In implementing and improving these tools the Group Leader in Matters of Safety ( GLIMOS) plays an important role in communication and control. Within the proven-out roles in safety management at CERN, the GLIMOS introduces and uses the improved tools throughout the CMS collaboration