- Hans Henrik Andersen
Hans Henrik Andersen (* 1937 Frederiksberg, Denmark) is Professor at the Niels Bohr Institute of the University of Copenhagen (
emeritus since 2004). He is co-editor of the scientific journal "Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms".He has made important contributions to various fields of
atomic physics andsolid state physics , especially in the field of the stopping power of matter for fast charged particles. The accuracy (0.3 - 0.5%) of his measurements is unsurpassed even today (2006). They were done by measuring the amount of heat deposited in a foil at the temperature of liquid helium (-269°C).Together with his collaborators, he succeeded in showing in 1969 that the stopping power for fast
alpha particle s is more than four times as large as that forproton s. Since theatomic number z of alpha particles is exactly twice as big as that of protons, that means that the stopping power is not exactly proportional to z^2, as the simpleBethe formula would have it. That was an additional proof of the existence of the Barkas-Effect.Literature
*Andersen H.H., Simonsen H., Sørensen H.: "An experimental investigation of charge-dependent deviations from the Bethe stopping power formula", Nuclear Physics A125 (1969) 171
*Sigmund P.: "Particle Penetration and Radiation Effects, General Aspects and Stopping of Swift Point Charges", Springer Series in Solid State Sciences Vol. 151, Springer-Verlag Berlin Heidelberg (2006)
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