New developments in the Next Linear Collider beam delivery system design

We review many developments in the design of the beam delivery system for the Next Linear Collider. The collimation system has been redesigned to reduce nonlinearities and ease tolerances, and the IP switch line has been adjusted to permit a 300 meter longitudinal separation between the two detectors. Magnet designs have been changed to reduce the number of distinct magnet classes, produce a smoother vacuum chamber, and improve pumping. A revised set of interaction-region quadrupoles achieves the optical requirements of the system with improved beam stay-clears, and performance of the final focus at various energies has been simulated and found acceptable. Studies have begun on the set of feedbacks required to maintain the stability of the system and the changes in tolerances thus implied.