1. 16/12/02GS/ALICE TB 1 Update on the ALICE Grounding Plan From draft document (June 02) The grounding plan for ALICE proposed in this document is based on general considerations, on corresponding plans worked out for other LHC experiments, and on established practices in other large experiments already on the floor. Certain issues are not yet fully resolved and require some study. The primary aim is to define a frame of realistic and effective guidelines to be implemented in each and all subsystems. Specific requirements will be dealt with in due time. A strong guideline in a number of experiments already in operation, and adopted as baseline in ATLAS and CMS, is that the subdetector reference grounds are designed to be electrically isolated from one another (and from safety ground). This is a very strong requirement that could in principle be embedded in a global grounding plan, if this were done at the very early stage of the design of the experiment. In the case of ALICE, it is not clear whether this condition could in practice be adopted and what effort would be required to implement it. Ultimately, it is not proven that this is really necessary. It is therefore proposed that a detailed modelling of the set of subsystems is done as soon as possible and that the discussion on this principle is deferred until the constraints are better understood.

2. 16/12/02GS/ALICE TB 2 Status of Subdetector Grounding Plans Dimuon Trigger –discussed with F. Szoncso/TIS==> received blessing –part of review of front-end electronics (Nov 02) –implementation under way TPC –draft document, already well detailed –sensitive issues insulation from rails insulation from mechanical supports of ITS, spaceframe, etc grounding of 100kV HV supply SPD –test under way on half-stave prototype

3. 16/12/02GS/ALICE TB 3 Comparison with other LHC experiments The ALICE document is probably the most concise It covers all the essential points –authors unbiased opinion - comments and criticism welcome ! Real test –ease of implementation –effectiveness requires at least part of system Parts missing or to be expanded –safety –methods of EMC & EMI testing –procedure to check grounding integrity

4. 16/12/02GS/ALICE TB 4 From Draft to Final (Proposal) Approve draft as ALICE basic grounding plan Add sections on safety (can depend on subdetector, eg TPC HV) Append subdetector implementation plans Place document on web page for consultation –extensive list of references is already available and will be expanded Dedicated 1 day workshop in the June ALICE week ? Reminder Continue pragmatic approach through general guidelines ( = rules, once verified) –but in the end Enforce acknowledged rules and monitor implementation integrity