Effect of H- stripped electrons on the LINAC4 profile measurements

At CERN's LINAC4 it is foreseen to measure transverse beam profiles by means of Secondary Emission wire grids (normally referred to as SEM monitors or SEM grids) and Beam Wire Scanners (BWS). Following observations at the SNS linac BWS, that showed cross-talk between wire signals attributed to scattering of H- stripped electrons, it was decided to investigate this effect for the LINAC4 case. The interaction of electron beams with Carbon and Tungsten wires was studied through Monte Carlo simulations (FLUKA code), analytical calculations, particle tracking simulations in EM fields (CST Particle Studio) and a laboratory experiment based on a 70 keV electron beam, well reproducing the case of 128 MeV H- ions.