• R.C. McCrady
  LANL, Los Alamos, New Mexico

The linear accelerator at the Los Alamos Neutron Science Center (LANSCE) accelerates both protons and H-minius ions using Cockroft-Walton-type injectors, a drift-tube linac and a side-coupled linac. The vacuum is maintained in the range of 10^-6 to 10^-7 Torr; the residual gas in the vacuum system results in some stripping of the electrons from the H-minus ions resulting in beam spill and the potential for unwanted proton beams delivered to experiments. We have measured the amount of fully-stripped H-minus beam (protons) that ends up at approximately 800MeV in the beam switchyard at LANSCE using image plates as very sensitive detectors. I will present the motivation for the measurement, the measurement technique and results, and calculations to model the results and possible mitigation schemes.