A modular optics design for the NuMI beamline; TOPICAL

The Nu MI beamline discussed here is a modular optics design, characterized by 4 sections: MI(yields) beamline matching; periodic FODO cells; a special insertion to traverse the carrier pipe, and a versatile final focus section to produce the desired spot-size on the target. The use of 21 quadrupoles ensures that beam size is constrained within acceptable bounds throughout the line-(beta) and lt; 60 m in the MI matching section and FODO cells,(beta) and lt; 125 m in the doublets of the carrier pipe insertion, and(beta) and lt; 100 m in the final focus. Lattice functions of the NuMI design are not unusually sensitive to errors arising either from MI optical mismatches or gradient errors, and are completely correctable through the 2 matching sections. Aperture studies indicate that the line is able to transport the worst quality beam that the Main Injector might provide. Dipole correctors at 19 of the 21 focusing centers are available to provide high-quality orbit control and further ensure that the NuMI line meets the stringent requirements for environmental protection