made a presentation
on the beam dynamics simulation code Lucretia
, emphasizing the two missing features which are needed to represent the current ILC lattice: some representation of the helical undulator in the electron linac, and a means to represent the IR solenoid and other "wraparound" elements.
The proposal was made to develop a new data structure for field maps in Lucretia which could be used to superimpose the wraparound elements for the IR or other locations (quads or solenoids which wrap around accelerating cavities, for example -- not very useful for the ILC LET, but maybe useful for other applications at SLAC). It was pointed out that combined-function quad-solenoid element maps can be calculated; the advantage of the field map approach is that it is more general, allowing if necessary a combination of the IR solenoid and a crab cavity (for example).
On the other issue -- the undulator -- several people noted that experience at light sources and at CESR-C with lumped element representation of insertion devices has been relatively poor, and that many accelerator labs have decided to represent the insertion devices with field maps. Given this, use of the same field map formalism might solve the insertion device problem.
Sergei Seletskiy has developed a code which does something similar to what was proposed; PT has been studying his paper on the topic, and plans to make heavy use of Sergei's results in implementing the field map tracker.
In terms of other features which would be useful, several people said that the Lucretia documentation was not a good tool for people who are starting out with it; it was compared to trying to start out in Linux by reading the online manual ("man") pages. A better tutorial-style starting out guide was suggested. The online documentation is also maddeningly vague about parsing -- new users don't realize that they need the mex'ed XSIF parser as well as Lucretia. Finally, it has recently been shown that accelerating cavity HOMs can be used to read out the individual positions of bunches in a train as well as the aggregated position of the full train, but Lucretia does not support this feature; it probably should do so, making use of the MultiBunch tracking flag which the regular beamline BPMs use.
Resulting action items:
- Add a better tutorial style Lucretia guide to the website and improved clarity on XSIF -- PT
- Study the undulator issue some more -- lumped element or field map? Person TBD
- Put together a demo version of the field map to show how it would work with the other data structures -- PT
- Understand the existing IR field map tracker -- PT with help from Sergei
- Multi-bunch HOM-BPM code -- PT with help from somebody (Glen? Steve? Jeff?)
Other activities and announcements:
- Accelerator Markup Language: PT and David Sagan @ Cornell are exchanging voluminous e-mails on the topic. There is a strong interest in transitioning ILC's official lattice specification format from Extended Standard Input format (XSIF) to AML over the next 3 years. Lucretia will support this format, probably starting sometime in 2008.
- The Low Emittance Transport meeting at SLAC will be 11-13 December. The website is here.
- Mark Woodley has established a mailing list for stuff related to ATF and ATF2 running. If you want to be added to the list, e-mail Mark.
There are minutes attached to this event.