Walter H. Barkas

Walter H. Barkas (* 1912 in Portland ( Oregon), † March 28, 1969 ) was from 1965 professor of physics at the University of California, Riverside. He was a specialist in the use of nuclear emulsions, ie, Photographic plates with thick sensitive layer for the purpose of particle physics.

Together with colleagues, he discovered the difference in range between positive and negative mesons of the same initial energy and attributed this to the difference in stopping power between positively and negatively charged particles. This difference therefore bears the name Barkas effect or Barkas -Andersen effect, see Bethe formula.