Jitter control and scraping in the 12-view AHF HEBT

The HEBT of the proposed Advanced Hydrotest Facility (AHF) is designed to deliver 50-GeV protons to an object from 12 directions, 15/spl deg/ apart. Individual beam bunches extracted from a synchrotron are split with 11 sets of septa such that, nominally, the same number of particles arrives from each direction. Extraction-kicker jitter can be expected, and can result in beam-intensity fluctuations in the 12 lines to the object. The HEBT tune is chosen to minimize this effect, with interesting consequences for the beam-splitting process. Beam splitting in each set of septa is initiated by a wire septum, with some particles hitting the wires. Particle-tracking simulations predict that activation of beamline components due to these affected particles can be kept low with sets of scrapers. They also predict that the scraping scheme is not sensitive to beam-position jitter from extraction-kicker jitter, or to average-energy jitter. Details of the jitter study and the scraping study are discussed.