1. 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

2. 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

3. 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

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

5. 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

6. 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

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

8. LSS Activities per topics

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

10. Preparation Activity for the LS1

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

12. 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…..

13. 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

14. 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, 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 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