COMPACT SUPERCONDUCTING FINAL FOCUS MAGNET OPTIONS FOR THE ILC

The QD0 quadrupole, the final focus magnet closest to the Interaction Point (IP) for the ILC 20 m crossing angle layout, must provide strong focusing yet be adjustable to accommodate collision energy changes for energy scans and low energy calibration running. It must also be compact to allow disrupted beam and Beamstrahlung coming from the IP to pass outside into an independent instrumented beam line that leads to a high-power beam absorber. In designing QD0 we take advantage of recent BNZ, experience making direct wind superconducting magnets. Here we review important considerations for the present design, report on progress producing a prototype, describe our compact quadrupole concept in greater detail, and relate this work to other ILC design challenges