1. SC - 08Jul'11LHCCryo - TechStop July 2011 LHC Tech Stop July 2011 LuMaMeJeVe 12 23 34 45 56 67 78 81 Empty QRL_C 1.8K Ref. CP7 Deg Pump ? Deg Pump Refill QRL 15mbar ? Test ? repump <50mbar Powering Quench RF Deg Pump 70mbar15mbar 1.8K70mbar15mbar SAM DFB SAM DFB SAM DFB SAM DFB Action plan for major stops (+multi instrum & other works)

2. SC - 08Jul'11LHCCryo - TechStop July 2011 And reality … Major finding: the screw compressor (P8, oil filters clogging mid June) was found damaged, with bearings showing exceptional stress Similar case than P4_Xmas: - Series problem ? - Too much axial force ? Confirmed by observations on oil circuit => Decision to treat similar compressors a.s.a.p Inlet (4bar) Outlet (20bar) Specific oil injection (22bar) to balance axial forces, Need to send more oil than pass through to screws ! About 35’000 hrs, bearings calculated for 70’000 hrs

3. SC - 08Jul'11LHCCryo - TechStop July 2011 Compressor station of LHC 18 kW@ 4.5 K Bldg: 15 x 45 X 9 Pinput : 4.5 MW Cool: 500 m3/h Noise: 105 dBA Pipe & fittings redone with larger diameters P8(1) done this Tech Stop, 2nd to factory, P4(1) & P18(2) done in shadow of P8 recovery, P6 to be done latest at Next Tech Stop

4. SC - 08Jul'11LHCCryo - TechStop July 2011 QUI Leaky HX (Jan’11) TuA (Spring11) P8 configuration, week-end CCs 6CV215 valve (P2) Tests for relocation Validated for P2 (TS) ! Sector 78 Sector 81 Extra flow Until compressor repaired! Some minimum flexibility recovered during Tech Stop Limitations

5. SC - 08Jul'11LHCCryo - TechStop July 2011 LHC Tech Stop July 2011 LuMaMeJeVe 12 23 34 45 56 67 78 81 Empty QRL_C 1.8K Ref. CP7 Deg Pump ? Deg Pump Refill QRL 15mbar ? Test ? repump <50mbar Powering Quench RF Deg Pump 70mbar15mbar 1.8K70mbar15mbar DFB SAM DFB SAM DFB SAM DFB Tentative d’illustration des activités Cryo LHC 1.8K UPS 70 mbar15mbar Rev2: P5_UPS effect + refinement 12/34 Rev3: QRL_12 test stopped earlier + P4/P18 QSCB oil pipes SAM New 70 mbar Re-pump CP 15 mbar

6. SC - 08Jul'11LHCCryo - TechStop July 2011 Status & Forecasts Overall situation under control, checking singularities here and there P8: Should be back Friday evening (22h t.b.c) Special: ALL triplets + D4Q5_R4 emptied, warmed-up 25K, pumped VAC