Hans Henrik Andersen

Hans Henrik Andersen ( born May 1, 1937 in Frederiksberg, Denmark, † November 3, 2012 ) was a Danish nuclear physicist. He was a professor at the Niels Bohr Institute, University of Copenhagen (emeritus 2004) and was co-editor of the scientific journal " Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms ".

He has made significant contributions to various fields of nuclear physics and solid state physics, especially in the area of the stopping power of matter for fast charged particles. The accuracy ( 0,3 - 0,5 %) of his measurements of the stopping power of thin films is unmatched to this day (2006). They were carried out by measuring the heat evolution in the foil at the temperature of liquid helium ( -269 ° C).

In 1969 he succeeded with employees to prove that the stopping power for alpha particles is more than four times as large as that for protons. Since the atomic number of the alpha particle as large as exactly twice that of the proton, this means that the stopping power is not exactly proportional, as it would correspond to the simple Bethe formula. This was a repeated proof of the existence of the Barkas effect ( after Walter H. Barkas, also Barkas -Andersen effect called ).