Racks Layout

Original Requirements

• Minimise the overall level 1 latency (total cable path)
• Consider incoming cable paths and location of CTP, TTC systems (now Silicon RODs may be most important?)
• Digital cables from PPM to CPM/JEM less than 10m (now less of an issue?)
• Ease of installation, use and maintenance

Constraints

• High fanout of equal length cables between crates
• Receivers crates in separate racks (Calo grounding rules)

Suggested Arrangement

• Both floors of USA15 used: niveau 1 for muons, CTP, TTC; niveau 2 for calorimeter.
• Contiguous central block of racks for the calo trigger
• Analogue cables arrive through holes in the shielding wall about 5 racks away from the centre each side
• Hence receiver crates on the outside
• Front panel cables to adjacent PPM racks
• Cluster and Jet/Et processors in the centre
• Maybe one central rack for TTCvi and ROD crates?
• CTP hits cables down through private hole in the floor
• Normally two centrally positioned 9U crates per rack