Protons, surface scattering

Two physically reasonable but quite different models have been used to describe the internal motions of lipid molecules observed by neutron scattering. In the first the protons are assumed to undergo diffusion in a sphere [63]. The radius of the sphere is allowed to be different for different protons. Although the results do not seem to be sensitive to the details of the variation in the sphere radii, it is necessary to have a range of sphere volumes, with the largest volume for methylene groups near the ends of the hydrocarbon chains in the middle of the bilayer and the smallest for the methylenes at the tops of the chains, closest to the bilayer surface. This is consistent with the behavior of the carbon-deuterium order parameters,. S cd, measured by deuterium NMR ... 

The chamber may also be equipped at 180° to the beam with a (silicon surface barrier) detector for analysis of scattered protons, which provides the option of performing quantitative light element analysis by RBS (q.v.). In certain applications RBS can determine most of the matrix composition and PIXE the trace element contribution. 

We perform numerical modeling of atomic processes in various real plasmas including LHD fuel-pellet ablation and short-pulse laser interaction plasmas [21], We are developing a mixed quantum-classical code to study excited hydrogen atom formation in neutrals of back scattered protons at wall surfaces. 

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