New AGS slow external beam switchyard

The original switchyard for the Slow External Proton Beam at the AGS of Brookhaven National Laboratory incorporated two current carrying, copper septa to split the beam into three parts. These septa were each .05 mm thick and intercepted a substantial amount of beam when, as often occurs, it was necessary to split the beam across its densest region. To adjust splitting ratios and optimize losses, a complex time consuming pattern of steering adjustments using various magnets was necessary. When the question of providing a fourth beam to a new target station arose, it was clear that adding a third copper septum in the very constrained space available would lead to unacceptable increases in the radiation and control problems. In order to circumvent these difficulties, it was decided to rebuild the switchyard using much thinner electrostatic septa as splitters and to provide a greater degree of independence of the various beam segments