Measurement of lateral straggling using a microbeam

An original method has been developed to measure the lateral straggling of sub-micron proton and alpha beams after passing through polymer foils of di fferent thickness. For this purpose, the microbeam. line at CENBG has been used in scanning transmission ion microscopy (STIM) configuration to delive r the ions in normal incidence on foils. The lateral spreading of the beam was measured using a collimated charged particle detector centred on the be am axis and placed 6.3 min behind the foil. When the beam was horizontally scanned in front of the collimator, its lateral distribution was measured s tep by step detecting particles passing trough the small aperture. Regular gaussian shapes were obtained and data were compared to the result of simul ations carried out using the SRIM Monte-Carlo code for 2.5 MeV protons and alphas in Mylar and Formvar thin Mms. (C) 2001 Elsevier Science B.V. All ri ghts reserved.