• DA in collision with HO and LR beam-beam
• Alternating crossing or same plane
• Difference between nominal and pacman bunches
• Influence of triplet errors

• Optics V6.4, with β* = 0.55 m
• Triplet errors from 2210 table + correction
• MADX optics, tracking with SIXTRACK (18 angles for (x₀,y₀), 10⁶ turns, 20 seeds), in LHC@home
• Tune scan with split of 0.01 and 0.02 between Q_x and Q_y, with step of 0.001

• Tune dependence dominated by beam-beam for corrected triplet errors
• Strong angular dependence of DA for HH crossing, better for HV
• Marginally higher DA for small angles and HV crossing
• Largely better DA for large angles and HV crossing
• Tune split of 0.02 is worse
• No alternative working point for HH crossing

• Triplet errors uncorrected (or partially corrected)
• Other WP
• Optics V6.5, with β* = 2 m
• VV crossing

• SF suggested to test the sensitivity of DA with different phase advances between IR1 and IR5, at least for 1 seed (i.e. with beam-beam and the triplet imperfections switched off)
• MG suggested to implement realistic magnet errors from measurements 
• YP claimed that VV crossing with WP below the (1,-1) resonance may be symmetric to HH crossing above the diagonal (to be checked).

• RA reported that new features for the LHC aperture model by S.Chemli were implemented by SR who will remain responsible for it even though he moved to AB/OP.

• Pressure on the SSS (10% of the preassigned in first 3 sectors missing). Started approval of SSS from sector 3-4.
• For dipoles half of the machine is preassigned, sector 5-6 to be preassigned.

• Review of quadrupole axis tolerances by YP and measurements by M. Buzio, in view of dropping the measurements provided by the AC mole in most of the SSS, due to lack of time, man-power and the pressure on installation.
• The proposal of reducing the measurement plan seems acceptable but should be finalized before end of January.

• Proposal for attendance of conference for the first 6 months of 2006 (EPAC) should be sent to MG.
• Budget is tight (available for 6-8 people).

• Issued an ECR for splitting the dogleg of the 1st and 2nd dipole modules in D3 further apart (50 cm) for the installation of a 2nd absorber due to excessive radioactive spray.
• Waiting for vacuum group comment.
• SF commented that 50 cm are small wrt to 100 m separation between D3 and D4 (negligible impact on strength and aperture).

• Error routines from field measurements for MADX using tfs table format.
• Same philosophy as with statistical errors.
• A new flag was added (BEAM4) which is as BEAM2 but in the real beam direction.
• The three main corrections are available (spool pieces in arc dipoles, triplet correctors and a2, a3 correction).

• FZ presented Eliot MacCrory (EMC) from Fermilab physics group who is visiting the group. EMC is working with L.Michelotti and J. F. Ostiguy in the implementation of a CHEF application, an interactive wrapper of several codes for tracking and optics calculations.

Colour code:

• Black: proposed agenda
• Red: outcome of discussion at the meeting