1. Tracker Goals o Main issue is to be able to run cold as more radiation is accumulated. o Due to “uncontrolled” humidity behavior, our present limit is around 0C. o Need to achieve reliably nominal cooling performance (coolant at -20C) after LS1. o Running cold implies improvements and consolidation on the following areas: Improve dryness of various cold volumes (sealing, flushing, instrumentation) Consolidation of the cooling plant system (including the brine circuit) Re-commissioning (Pixel, SS at lower temperatures) September 29 2011Tracker Silicon Strips1

2. Tracker: Key point in preparation for LS1 o During this YETS11, assess the performance of the current “Brine” primary circuit with the goal to be able to operate the 7 cooling plants to nominal temperature + the new CO2 plant. o Increase the dry-gas (N2 + Air) flushing capability o Pixel clean room need to be ready o Advance procurement of all instrumentation and material, mock-up practice, etc. o New pipes for phase I pixel ? Need to decide o Preparing the new CO2 cooling plant September 29 2011Tracker Silicon Strips2

3. Tracker: key points for LS1 o Humidity seal most challenging: o Detailed efficient planning needs to be developed o Whenever possible, organize it in self-consistent parts, fully qualify them and move on o Need to coordinate efficiently with other activities from Tracker, HB and EB inside the solenoid. o Cooling system consolidation (pending also the “brine” ultimate performance assessment) o Ancillary system consolidation (thermal screen, heating foils, monitoring and instrumentation, dry-gas system, etc.) o Re-commissioning activity to validate all the work done and establish new running condition for both Pixel and SS tracker. o Installation of the new cooling plant September 29 2011Tracker Silicon Strips3

4. More on THIP as shown at the TC retreat 2011 September 29 2011Tracker Silicon Strips4

5. Silicon Strip Tracker: Winter Technical Stop 2011-2012 o These issues are discussed for both Silicon Strip and Pixel within the THIP group: https://indico.cern.ch/categoryDisplay.py?categId=3574 https://espace.cern.ch/cms-tracker-engineering/THIP/default.aspx o In the general area of been able to run the tracker colder, many activities are planned during this winter break which do not depend upon CMS opening (cooling plant cabinet, dry air system, N2 system, etc.) o In the assumption CMS will open during this coming winter: a)Improve humidity (both absolute value and stability) in the most critical area (just outside the tracker bulk-head) on a few sectors [time estimated 3 days + 2 contingency, testing also during the night] b)Test the concept of an extended “baggy” [time estimated 3 days] c)Add suitable dew point sensors (FOS, sniffing lines, other sensors) in the most critical areas [in parallel with a) and b) activities] September 29 2011Tracker Silicon Strips5

6. Improve humidity just outside the tracker bulk- head 1.Intervene on the BH to PP1-channel gap with the purpose of “boxing” a minimum region of 1/16 (i.e. one PP1 worth) or multiple of it. September 29 2011Tracker Silicon Strips6 Last Section of a PP1-Channel Region to be “boxed” A C B Pipe insulation ends ~here Tracker bulk-head

7. Improve humidity just outside the tracker bulk- head 2.Add another line for dry air (roughly same throughput of present PP1 line) to blow directly in the region where pipes are (mostly) without insulation. Add instrumentation as appropriate (FOS, sniffing line, other sensors) September 29 2011Tracker Silicon Strips7 Extra dry gas flow A C

8. Improve humidity just outside the tracker bulk- head 3.Adding another sealing barrier is currently under discussion with TC. The idea is to seal in a more favorable place, isolating a smaller volume around the Tracker BH, avoiding air sipping through HE,EE from reaching the BH region. September 29 2011Tracker Silicon Strips8 This seems the best place to add a 2 nd sealing

9. Test the extended “Baggy” concept September 29 2011Tracker Silicon Strips9 1.The concept relies on applying a <1mm thick sheet of vapor barrier material (“plastic bag”) to the whole inside surface of the solenoid, from the Pixel/Beam pipe region to the inflatable sealing region on the edge of the vac-tank. See next slide 2.The idea for this winter break is to see how to best cope with the extremities (pixel/beam-pipe and edge of vac-tank) and install a section as a test in preparation for LS1 application. 3.If more time is available we could extend the intervention to complete one end of both ends of the solenoid. Proper sealing of the vac-tank ends would require more time than likely available this winter.

10. Test the extended “Baggy” concept September 29 2011Tracker Silicon Strips10 1 2 6 4 3 7 1. Beam-pipe / Pixel volume seal 2. TK bulkhead 3. TK service channel start 4. TK + EB + HB service channels 5. TK PP1 6. CMS inflatable seal 7. CMS endcap Continuous vapor barrier up to PP1s or edge of vac-tank Potting of services 5 Inner Seal

11. Conclusions September 29 2011Tracker Silicon Strips11 o 3 Major goals: 1.Improve isolation (2 parallel methods) 2.Increase dry gas flow 3.Improve instrumentation o Test the areas we have worked on in realistic conditions with beam during 2012 o As more time becomes available we could extend the scope of the intervention to larger areas of the vac-tank.

12. Overview of the inside of the solenoid volume September 29 2011Tracker Silicon Strips12