D. Calzolari, Y. Dutheil, J. Keintzel, S. Kostoglou, G. Nigrelli, A. Potet, P. Raimondi, K. Skoufaris, S. Yue

• Present status of the WG simulations
• Concerted results documented in the comparison report -> injection efficiency only with SR
• Concerns arose on the status of injection efficiency in the presence of more complex modelling
• Focus in ABT on the injection concept and following evolution of tracking results in a collaborative repository https://gitlab.cern.ch/abt-optics-and-code-repository/projects/collider-injection-fcc-e
• In ABP mostly focused on Xsuite, although with benchmarks on SAD and superKEKb at injection presented by G. Nigrelli https://indico.cern.ch/event/1588696/contributions/6856980/
• The WG members have many more simulations, with injection bump, beam-beam, optics perturbation due to the bump, non-linear dispersion
• Collider design pillar request for information
• Q1 : What is the injection efficiency modelled in the presence of beam-beam and collimation ?
• No resources identified are listing efficiencies of 0%
• This remain an ongoing topic of discussion with continuous progress on both performance and inclusion of more physics processes
• Besides including all physics processes, the injection process must be tested under perturbed conditions (corrected lattice) to test and quantify the robustness of the injection process.
• Latest simulations conducted and presented by G. Nigrelli  https://indico.cern.ch/event/1588696/contributions/6856980/
• Q2 : Is the injected beam position and Twiss parameters including both linear and non-linear dependency with momentum offset ?
• Discussed during the WG meetings of 10/2026 and 12/2026 as well as by G. Nigrelli at the tune-up meeting in October
• But need to understand and fix specific parameters -> Important to find the parameters and communicate them
• Important to find the optimum injected beam parameters -> We need to establish a methodology to find new parameters with a new lattice
• Giulia will discuss with Sen on how to incorporate or associate her simulation to a repository, for instance the https://gitlab.cern.ch/abt-optics-and-code-repository/projects/collider-injection-fcc-e
• Marc-Andre on LCC
• Previous lattices not optimised for injection or non linear dynamics
• It would be important to conduct optimisation from a corrected lattice with errors (request to tune-up WG ?)
• Conducting MOGA at large dE
• voltage presently using 150 MV which is slightly away from the baseline set to 90 MV (convergence needs to be done on ABP-RF side)
• Optimisation conducted to dispersion-free straight section
• Optimised lattice is able to maintain the DA w/ beam-beam and epsY
• At the location of the septum the optimisation includes up to DDX2 which may be the source of limited DA -> agreement that included higher order is important
• Present point selected for higher MA but could be optimised for slightly larger DA for hybrid injection
• How do we proceed from here ?
• 90MV or stay at 150 MV for now ?
• Should we switch to negative dE ? -> This is needed because we need lower RF voltage from the booster
• Kyriacos asks if optimise directly on lifetime instead MA
• MA should be a good proxy to lifetime but one scan should be conducted to confirm this
• Marc-Andre will publish and make available a new lattice version, note this is not a new lattice but optimised element strength on LCC106
• Sen on MIK progress
• No time during the discussion, only conclusion with promising zero-phase-advance concept
• The beam stay clear definition remains in question, Giulia will circulate the definition with beta and dispersion contributions
• The pi-phase advance concept requires contributions from Marc-Andre to establish the feasibility in PB
• Detailed discussion deferred to the next meeting