Redesign of the LAMPF Transition Region

We describe the redesign of the transition region (TR) that functions as a transport section for the H+ and H- beams between the LAMPF 201.25-MHz drift-tube (DT) and 805-MHz side-coupled (SC) linacs providing a 7.98 cm longer flight path for one beam so that both beams have the correct phase for capture in the SC linac. In the new TR both beams from the DT linac are independently matched to the acceptance of the SC linac. The relative phase adjustment between the two beams has been simplified and is now accomplished with just one control. A straight-through section has been added to facilitate beam studies under less complicated conditions. The aperture has been increased to reduce beam losses. Diagnostic equipment allows measurement of the transverse output emittance of the DT linac. We discuss both the criteria placed upon the beam in the TR and the predicted performance in matching a variety of beam shapes from the DT linac to a variety of SC accelerator acceptance shapes.