Cavity shape and beam dynamics design for a linac for pions

A linac to accelerate pions from 400 to 920 MeV kinetic energy is being designed as an upgrade to the LAMPF accelerator facility at Los Alamos, New Mexico. Calculations for the design of the superconducting cavity shape attempt to reduce the peak surface field needed to achieve a given accelerating gradient, yet ensure sufficient cell-to-cell coupling to maintain field stability when microphonics or other tuning errors are present. The beam dynamics design has the goal of getting the highest possible flux of pions in a narrow momentum range at the end of the linac. In order to do this, the design takes into account the survival fraction from pion decay, and optimizes the acceptance of the combination of the transport line from the pion production target to the entrance of the linac and the linac itself.<>