MAD-X: An Upgrade from MAD8

The development of MAD8 has been suspended for many years. At the start of 2001 it was decided to revive it and put it into a more maintainable form since it is needed for the LHC during design and operation. In particular, the home grown dynamic data management in Fortran77 limits further extensions, and is not guaranteed to survive for another ten years. In fact, MAD-X has been originally planned to be a copy of MAD8 with a more modern data management. The data structures that hold the information about the accelerator, and the interfaces to the modules are written in C which provides the dynamic data structures needed. Contrary to MAD8, the MAD-X modules are designed as truly independent entities; they are much simpler and therefore better maintainable. It was also thought important to spread the responsibility for the various MAD-X modules among several accelerator physicists. Lastly, an upgrade of MAD-X is being planned to improve the physics models and to include map related tools using Etienne Forest's PTC (Polymorphic Tracking Code) code. A fully operational and documented version is available via the MAD-X web site.