Mark Woodley made a
presentation on the status of the ILC lattices as of the ALCPG meeting at the end of October, 2007. He has integrated the source lattices which were given to him by the area deckmasters into a single set of lattices that has a common coordinate system. Some of the geometries were changed to make this happen (system lengths, arc angles), and names were changed to resolve name conflicts between lattices. This means that deckmasters should use the
current production set of lattices as the starting point for further work, rather than the source files that they originally gave Mark. In the process of getting the lattices together and the geometry right, Mark broke some of the betatron and dispersion matching within and between lattices, and that will also need to be fixed.
Several questions came up during this presentation:
- Mark needs MAD-ready versions of the DR injection / extraction lattices, in which the kickers are treated as SBENDs and the quads that the kicked beam passes through off-axis are represented as gradient bends. Ina said she had this available and would get it to him. This means that there will be some elements which are "double-counted" -- treated as kickers in the ring lattice and bends in the inj/ext lattice, etc -- but for now it can't be helped, since MAD-8 does not support arbitrary changes of the coordinate axis that is used to align the accelerator components.
- Some changes to the inj/ext lines will be needed when the new DR lattice enters production; that is still scheduled for Jan 1, 2008.
- The DR tunnel is 5 m ID, the injector tunnel is 4.5 m ID; how do the tunnel floors line up? (Note: some new information has been posted on this since the meeting).
- Does the injector tunnel meet the linac tunnel in the linac area, or the BDS area? There might be advantages to having the meeting point in the BDS area, since the service tunnel alignment moves away from the beam tunnel alignment in the area where the linac and injector tunnels meet (see here for details); that change may have implications if there are klystrons in the service tunnel and cryomodules in the linac tunnel in that area.
PT showed a
slide from Tom Lackowski which details the current thinking on the layout of the tunnel junction area. This slide has dimensions, radii of curvature, etc, which should be enough information for area leaders to start laying out their beamlines.
PT led a discussion of the
punch list of known lattice problems. There was some discussion on the central injector issues (there is now a
file posted which summarizes the recent discussions on central injector stuff). The question came up about how to represent the e+ production undulator in the linac areas; no obvious answers presented themselves.
Action items from this meeting:
- Ina to get Mark MAD-compatible versions of the DR inj / ext lines: (done, I think)
- PT to gather some information on the central injector issues (done)
- Deckmasters to review their items on the punch list and bring questions to PT and Mark
- PT and Mark to contemplate the problem of representing the undulator
There are minutes attached to this event.
Show them.
