Walter H. Barkas

Walter H. Barkas (1912, in Portland (Oregon) - 28 March 1969) was Professor of Physics at the University of California, Riverside from 1965 on. He specialized in the use of nuclear emulsions, i.e., photographic plates having a thick sensitive layer, for purposes of Particle physics.

Together with his collaborators, he discovered the difference in range between positive and negative mesons of the same initial energy, and he ascribed this effect to the difference in stopping power between positively and negatively charged particles. Hence, this difference is called Barkas effect or Barkas-Andersen effect, see Bethe formula.

Barkas was a visiting scholar at the Institute for Advanced Study in 1938-40.