Ramsauer-Townsend effect

Kauppila, W.E., Stein, T.S. and Jesion, G. (1976). Direct observation of a Ramsauer-Townsend effect in positron-argon collisions. Phys. Rev. Lett. 36 580-584. 

The ab initio PSCF approach provides quantitative descriptions of the Ramsauer-Townsend minima in methane and silane where very low energy experimental data are available. In the calculations performed to date it appears that this effect is ubiquitous at least in non-polar hydrocarbons, but that conclusion awaits experimental studies at low energies on more hydrocarbons. 

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