The studies are being continued with particular emphasis on dynamic acceptance. Increasing the current per bunch is another way to improve the luminosity at high energy. The transverse mode coupling instability is limiting the intensity at injection. Finally increasing the number of bunches can give a higher luminosity. A pretzel scheme with 8 bunches per beam has been used in the past.
Studies are underway to find which method is most promising to reach a high luminosity.
The LHC basic lattice design in its version 4.1 was made available in the first part of the year. The optics activities are now directed to the study of the flexibility and robustness of the lattice and dynamic aperture. An impedance database is being set up with automatic calculation of instability thresholds and parasitic losses. Measurements of RF surface resistance for the beam screen and of beam echoes are scheduled for the next months. Space charge effects are being reviewed and, in particular, the calculation of magnetic Laslett coefficients and of transient phenomena at injection.