2015 strategy overview

2015 will be a re-commissioning, re-conditioning year. Following initial commissioning with beam, the intensity and performance ramp-up will take longer than it did in 2011 and 2012.

• 2015 starts with system tests in parallel with hardware commissioning. Dry runs of operations functionality also in parallel.
• This is followed by the Machine Checkout with particular attention to machine protection commissioning.
• Low intensity commissioning with beam of the full operational cycle will last about 2 months. This will include first pass machine protection commissioning and validation in parallel with system commissioning.
• An exit condition of the beam commissioning phase is first stable beams with a low number of bunches and low luminosity.
• Scrubbing for around 9 days will be required early on (partially with 25 ns beam) paving the way for 50 ns operation.
• Intensity ramp-up with 50 ns is the foreseen. This will take 3 weeks or so. During this stage system commissioning with higher intensity continues (instrumentation, RF, TFB, injection, beam dumps, machine protection, vacuum...). Variables at this stage: bunch intensity, batch structure, number of bunches, emittance. Physics fills can be kept reasonable short during this phase given the experiments lack of interest in accumulating too much 50 ns data.
• Following the intensity ramp up a reasonably short period of 50 ns operation is envisaged. This will be used to characterize vacuum, heat load, electron cloud, losses, instabilities, UFOs, impedance. Nominal bunch intensity (1.2e11 ppb), beta* 80 cm, normalized emittance of 2.5 microns gives ~4.5e33 cm^-2s^-1 and a pile-up of around 27. We would image less than, or up to, 1 fb^-1 being delivered during the 50 ns ramp-up/running-in phase.
• Thereafter 14 days scrubbing will be required for 25 ns operation, followed by a gentle intensity ramp up with 25 ns dictated by electron cloud conditions with further scrubbing as required.
• Initial performance with 25 ns: in the 25 ns run at the end of 2012, 25 ns physics was delivered with up to 400 bunches. An 800 bunch attempt was dumped by ALICE going into collision. The beam was made up of batches of 96 bunches (2 injections of 48 from the PS to the SPS). Electron cloud was manageable because of the reduced batch length (nominal would be 5*48 = 240). If we imagine being able to get reasonable quickly up to 800 bunches we should be able to deliver something like 0.5 fb^-1 per week during initial 25 ns operation.
• 50 ns is held in reserve as a long term operational option only in case of serious problems with 25 ns.

Full schedule here. Given a timely start of beam commissioning, the timing of the technical stops is more-or-less fixed. MD is more flexible, and as noted on the full schedule, the timing of the scrubbing runs is indicative and will ultimately depend on progress with beam.