The main reason to have a LIU Beam Parameter Working Group is to create a platform where experts from the different machines meet and discuss together the LIU management to steer machine and simulation studies needed to improve our prediction of future LHC beam parameters. Besides, strategies and actions can also be defined to make sure that the LIU beam parameters remain as close as possible to the HL-LHC target parameters.

• LIU beam parameters are calculated under a set of assumptions
  • To be validated/checked with simulation and/or machine studies
  • To be reviewed and fed back into the parameter table, if necessary
• LIU project is in evolution
  • The continuing studies can unveil new options or constraints at any time
  • Changes of baseline may follow events like the Cost & Schedule review(s), MTP update, etc... and this may need to be reflected in the beam parameters
• New beam variants can become interesting and need to be analysed

Therefore, for both protons and ions, it is necessary to:

• Regularly monitor the consequences of the evolution of the LIU program on the LIU parameter list
• Steer the necessary machine and simulation studies, and analyse the resulting impact on the LIU parameter list (e.g. in terms of assumptions)
• Check any evolution for the LHC beam variants that need to be considered in our official parameter lists
• When necessary, and possibly not too frequently anyway, adjust/revise the parameter tables and release new versions for official use (with due communication to out HL-LHC colleagues)

Meetings will take place ~once a month (dates for 2016 to be sent out shortly to save te dates).

Examples to assumptions that need to be validated (or anyway checked, studied, proved) for protons are: PSB brightness line with Linac4, longitudinal beam parameters at PS injection (bunch length and longitudinal emittance), intensity limitations in the PS and SPS.

For the ions, the parameter lists are not yet very clearly defined. What is needed:

• Build a consistent “Achieved” table based on 2015 measurements throughout the chain (with present loss and emittance growth –where measurable).
• Build the baseline LIU scenario by fixing the assumptions (again based on educated guesses from 2015 experience for loss/emittance growth budgets, but also from the projected performances of LEIR/PS/SPS after upgrades) to propagate parameters through accelerators.
• Develop alternative scenarios to fulfil the HL-LHC requirements are specified in John's EDMS paper