Long Shutdown for the LHC: Vacuum Beam Pipes Outline Why a long shutdown? Master planning Beam vacuum Pipes Long Straight Sectors ARCs Preparation Activities Start-up Scenario G. Bregliozzi on behalf of LBV Section Group meeting 26th – October 2012

Why a long shutdown? Main priorities Environment of main IC splice Repair defectuous interconnects (powering at 7 TeV) Consolidate ALL interconnects with new design 10-15 % of interconnections to be opened and to be re-welded 100% (10’170) to be consolidated Finish off pressure release valves work (DN200; 4 sectors: 2-3, 4-5, 7-8, 8-1) Bring all necessary equipment up to the level needed for 7TeV/beam Repair He leaks (sectors 3-4 and 4-5) Maintenance of all the systems after 3 years of operation Environment of main IC splice Magnet Splice Consolidation

Magnet Splice Consolidation The main dipole and quadrupole magnets in each of the eight sectors of the LHC are powered in series. About 105 interconnections are present used connect each others. The main 13 kA interconnections between the LHC main magnets are made of soldered joints (splices) of two superconducting cables stabilized by a copper bus-bar. The accident in LHC in September 2008 started in one of these bus bars, where an excessive resistance,most likely in the splice between two SC cables due to the lack of solder, caused the joint to quench. In combination with a bad contact between cables and copper stabilizing bus-bar this had resulted in a thermal run away at about 8.7 kA and finally caused a significant destruction of the magnet system in the LHC tunnel. g-ray pictures have shown the presence of many of such defective joints in the machine

Master Planning From February 2013 to December 2014 2013 2014 Feb. Jan. 2015

Long Shutdown for the beam vacuum pipes: What else? Collimators TDI MKI New Beam Instrumentation Equipment RF VSC Consolidation Splice Consolidation Experimental Area VAX Update NEG and Ecloud Pilot Sector

Activity in the ARCS and Stand Alone Magnets All the ARCs will be warmed up: Leak detection during the warming up When opened: RF ball test to determine plug-in module position after the warming. Rupture disk installation Pump down Leak detection Venting Second RF ball test RF ping-pong ball During warm up of the ARC possibility of buckling modules Use of a ball with inside an RF transmitter The BPM all along the beam pipe will detect its position Activity followed by J. Finelle

Acitivity in the long straight sectors (LSS) Just 700 m over 5800 m of beam vacuum chambers still under vacuum

LSS Activities per topics

LSS Activities per topics Collimators DFBA BI Equipments ALARA (LSS3 and LSS7)

Preparation Activity for the LS1

Production, design, integration, tests and upgrade of new layout

Production, design, integration, tests and upgrade of new layout Exchange of VMTSA bellows moduels Modified Ion Pump for NEG Cartridge Integrations New TCDQ in LSS6 New modules for NEG Cartridge Integrations New sectorization of the TDI And much more…..

Experimental chambers test and validation VA ATLAS Experimental chambers test and validation UX85-3 Berillium LHCb Leak detection Degassing measurement NEG pumping test UX85-2 LHCb Anular Pump ATLAS UX85-4 LHCb Endcap CMS Activity followed by G. Lanza

Restart scenario for physic fills after the LS1 2 days 6 days 4 days Rough time estimate for first scrubbing run after LS1 (2014) ~50h = 2 days machine time, as was needed in 2011, to lower dmax from 2.1 to 1.55 (including set up of all injection steps, 72-144-216-288 bunches) An additional 20h net beam time with 2100 bunches to get to 1.45 (scrubbing limit at flat bottom), estimated with a simple model (Chamonix 2012) = 6 days machine time (applying scrubbing factor from 2011 = 0.14) At least 4 days machine time for operation & further scrubbing at 7 TeV with increasing number of bunches (perhaps gradually including ramps at intermediate energies?) Total of 12 days with very good machine availability and no contingency Scrubbing scenarios could also foresee a staged approach First, “light” scrubbing with 25ns beams (few trains @injection) to allow a period of electron cloud free operation with 50ns and intensity ramp up. Then, full scrubbing for 25ns operation In subsequent years, scrubbing should go much faster because, in absence of venting, de-conditioning is weak and re-conditioning much faster Thank you for your attention