ATLAS UPGRADE BARREL END SERVICES – Work on trying to reduce mass of cooling in R/PHI TJ Fraser UCL Assuming cooling pipes have to be directed to specific narrow channels on the cryostat and cannot be spread around phi then layout must include manifolding for cooling output on the barrel end. This also reduces the considerable mass. On the existing SCT barrel, there is one cooling pipe per row of modules. On the upgrade barrel, there will be two cooling pipes per stave. Need to reduce numbers of pipes as close to barrel as possible if you want to use EC detectors! Otherwise you have an Iron Curtain (well stainless steel probably) One way to do this is could be to manifold pairs of pipes close to the barrel end so that mass is reduced. The number of pipes would then be closer to the current SCT. To bring two cooling pipes of the same type closer, to reduce mass of bridge, alternate staves could be reversed with respect to cooling pipe flow, so that stave at phi1 would have exhaust on left and input on right (looking end on) and stave at Phi2 would have exhaust on right and input on left etc. The design of the short links could include strain relief. Ongoing / Future work : continue with CAD drawings and excel spreadsheets. Lots of possibilities to try out in order to reduce mass at the barrel end but at the same time trying not to increase the size of the envelope in Z.

normal stave reverse stave Upgrade Barrel end services (all layers)Total %Xo/side comparison

Total %Xo/side COMPARISON of UPGRADE with PRESENT SCT BARREL COOLING at Barrel end – Output and Input pipes – normal vs reverse stave OUTPUT – present SCT barrel spiders comparison with 2 types of upgrade stave Comparison with reverse cooling stave INPUT – present SCT barrel capillaries Comparison with 2 types upgrade stave Comparison with reverse cooling stave existing SCT existing SCT existing SCT existing SCT Upgrade (3 layers short stave) normal cooling staves Upgrade (3 layers short stave) normal cooling staves Upgrade (3 layers short stave Upgrade (3 layers short stave) reverse cooling stave reverse cooling stave

bus cooling normal stave buscooling reverse stave Total %Xo/side for bus and cooling for Upgrade – all staves (3 short and 2 long) Comparison of normal stave with reverse stave cooling, with constant mass for bus. Note: cooling assumed here to be CO2 with 3mm OD cooling pipe on stave and with all cooling pipe on barrel end stainless steel (for Upgrade). Opto components not yet included.