1CERN - 14/05/23Claudio Bortolin

CLAUDIO BORTOLINCLAUDIO BORTOLIN

INFN – PD / CERNINFN – PD / CERN

2CERN - 14/05/23Claudio 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

3CERN - 14/05/23Claudio 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

SPDPP4

PP1

Dummy sector

To the plant

Test a real line and the real plant with the dummy sector using alreadymasked 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 collaborationasked us to weigh the pros and cons carefully before deciding to do it

Miniframe

TPC

7CERN - 14/05/23Claudio Bortolin

beginning of 2012

beginning of 2013

Workshop in Chamonix (24th -28th 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:

8CERN - 14/05/23Claudio 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

9CERN - 14/05/23Claudio 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

11CERN - 14/05/23Claudio 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. ?