Thin Si3N4 windows for energy loss STIM in air

Abstract The use of thin (102 nm) windows of Si 3 N 4 to transmit an electronically rastered microbeam of MeV protons into ambient air with small scattering is reported. The windows were made by anisotropic etching of Si, exposing about 1 mm 2 of silicon nitride film integrally attached to a silicon supporting frame. Stress measurements on films of several thicknesses yielded a value of Young's modulus of 350 GPa. Energy loss scanning transmission ion micrographs of several small living animals are presented. Focused beams of 100 pA have been passed through the films without failure.