1 CERN - 19/03/2016 Claudio Bortolin CLAUDIO BORTOLIN INFN – PD / CERN

2 CERN - 19/03/2016 Claudio Bortolin  Reduced cooling performance after the installation in the cavern : inline filters in PP3 local thermodynamical conditions close to the detector (thermal pick-ups?)  Test with fine-grained carbon powder:  Little pollution =>> huge flow reduction Test with epoxy glue: the “surface effect” is less effective SEM analysis: 25% of the filter was masked by powder. Flow reduced about 35%.  Dummy sector tests with real plant in the cavern: can give us more information and confirm some results  Reduced cooling = reduced electronic performance

3 CERN - 19/03/2016 Claudio Bortolin 2) counter-flow loops cleaning with C6F14, 48 hours per sector 3) Test session: dummy sector in PP1 with qualified (*) masked filters. The test will be performed on 2 bad loops by-passing the detector. 1) Loops cleaning with nytrogen January 2011 * We already measured the pressure drop on these filters

SPD PP4 PP1 Dummy sector To the plant Test a real line and the real plant with the dummy sector using already masked and classified filters. PP3

Removing the filters in PP3 involves the following actions: 1) Opening the ALICE experiment 3) Removing the miniframe 2) Disconnecting all the experiment services (cables, optical fibers, cooling pipes...) 4) Moving out the TPC detector The impact of the above is so important that the ALICE collaboration asked us to weigh the pros and cons carefully before deciding to do it

Miniframe TPC

7 CERN - 19/03/2016 Claudio Bortolin beginning of 2012 beginning of 2013 Workshop in Chamonix (24 th -28 th January): the long LHC shutdown will be scheduled (14-16 months) The filters in PP3 can be removed only during the long shutdown Two possible scenarios:

8 CERN - 19/03/2016 Claudio Bortolin 1. To insulate the input lines with Armaflex 3. To connect the dummy sector in the cavern with the loop of the sector 9 and test it for several weeks (“Ice age” test should be repeated): it implies SPD sector 9 OFF (not a big loss…) Outcome of a recent meeting with INFN Referees and experts 2. To install input pipes with reduced diameter to gain flow velocity 4. To build a replica of the plant and test it on a long term for possible material-related issues; (the plant parts can be reused as spare parts for the real one in the cavern) This was the most warmly supported suggestion

9 CERN - 19/03/2016 Claudio Bortolin 1.masked filters characterization and verify which is the component that introduce impurity in the loops 2. Systematics of the cooling performance at different t.d. conditions To carry on the tests with the dummy and the real sectors in DSF and reproduce the behaviour observed in the cavern: To obtain reliable results we need to use the same plant used in the cavern: a replica 3. Investigate reliability of flow simulations

Read-out system is ready Spare sector available Pipes installed Mini-plant to be modified

11 CERN - 19/03/2016 Claudio Bortolin If the long shutdown will take place in 2013 we need to find any possible solution to keep or improve the performance of SPD for the next 2 years! 1.Carry out tests in the clean room: shall we build a replica of the plant? shall we use the small plant we already have? 1. Search for an “endoscope” solution to access to the filters in PP3? 2. Look for reliable flow simulations Alternative strategies: 2. Chemical solutions? 3. ?