NUCLEAR MICROANALYSIS BY MEANS OF 350 KEV VANDEGRAAFF ACCELERATOR

An inexpensive and quantitative method to depth profile hydrogen and helium isotopes in low-Z materials (Z less-than-or-equal-to 25) by ERD E x B and, simultaneously, elements heavier than the substrate by RBS, has been developed. It uses a 350 keV He+ beam, low-noise ion-implanted detectors and a filter built out of crossed magnetic and electric fields. Typically, with this setup, the depth resolution (which depends significantly on the materials) is approximately 4 nm at the surface degrading to approximately 15 nm at a depth of 100 nm, while the depth probed is approximately 100 nm for H and He and approximately 500 nm for heavier elements. The sensitivity is approximately 1 at.% for H and He, almost-equal-to 0.1 at.% for other light elements (e.g.: C, N, O, etc.) and 1 ppm for heavier elements such as gold. It is also possible to use a 350 keV H-1+ beam to simultaneously depth profile heavier elements by RBS and identify them by PIXE. These combined techniques are especially useful to detect elements with neighbouring Z, such as stainless steel components.