LHC Commissioning with Lead Ion Beams

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HI2011, the 2011 Pb-Pb run

The commissioning plan for 2011 may still evolve in detail.  It fits in the overall LHC schedule.

The primary goal of this run is to deliver a substantially increased integrated Pb-Pb luminosity, as compared with 2010. 

A secondary goal is to continue the feasibility study for p-Pb operation that will be started in the LHC MD period in Week 44.  If successful, an attempt may be made to deliver p-Pb collisions in the ALICE, ATLAS, CMS and LHCb experiments.

Recent presentations and papers relevant to HI2011 and the p-Pb feasibility test:

• Presentation at LHC Physics Programme meeting (19 September 2011) to be updated 31/10/2011
• Overview talk at Europhysics Conference on High-Energy Physics 2011 (20-27 juillet 2011)
• Prospects of p-Pb collisions during the 2012 LHC HI run (17 October 2011)
• LHC Machine Committee, Meetings nos. 111 (19/10/2011), 107 (21/9/2011), 92 (18/5/2011)
• MSWG meeting 14/10/2011 (for status of injectors)
• CERN Machine Advisory Committee, 4th Meeting (22-23 August 2011)
• EPAC 2011 conference papers:
  • CERN Document Server- Ions for LHC- performance of the injector chain
  • CERN Document Server- First run of the LHC as a heavy-ion collider
  • CERN Document Server- First ion collimation commissioning results at the LHC
  • CERN Document Server- Luminosity and beam parameter evolution for lead ion beams in the LHC
• Chamonix 2011 LHC Performance Workshop (24-28 January 2011)

 

HI2010, the 2010 Pb-Pb run

This information is kept for historical reference.

The LHC will collide lead 208 nuclei (fully stripped ions).  There are two reference sets of beam parameters for the eventual full energy operation (7 Z TeV or 2.76 A TeV per beam), the "Early" and "Nominal" ion beams, as described at:

LHC Design Report Chapter 21 The LHC as a Lead Ion Collider 

Early Ion Beam Run

These notes refer to the commissioning of the Early Ion Beams for the first ion run in 2010 at 3.5 Z TeV or 1.38 A TeV per beam.  It is assumed that we will provide collisions in ALICE, ATLAS and CMS.

Although the energy was not then known, some background was given at the 2005 Chamonix Workshop: LHC Operation with Heavy Ions

NEW: Commissioning plan for Stage I, the first run with the Early Ion Beam in November 2010.

Commissioning the lead ion beams will be done on a machine that is already working well with protons.  It can therefore be assumed that the LHC's magnetic cycle has been established and is working reasonably well and reproducibly.  The experience gained in reaching that stage has been incorporated into the time estimates for, the commissioning of Pb ion collisions.

The lead ions have the same magnetic rigidity and geometric emittance as the protons.  Assuming the machine has sufficient magnetic reproducibility that it is not necessary to re-commission the injection, ramp and squeeze on every proton fill, then it should NOT be necessary to do much to re-commission the first turn, injection and ramp for ions.  Nor the squeeze of IR1 and IR5.   The main items to be dealt with include:

• RF - a larger frequency swing between injection and collision energies
• Filling pattern - this is currently evolving with a view to roughly doubling the number of bunches.
• Beam instrumentation setup - some instruments will be working close to their limits
• IP2, IP1 and IP5 will have zero net crossing angle.