Hartmut Paul Kallmann (5.02.1896-11.06.1978) was a German physicist. He was born in Berlin. He graduated from the University of Berlin (1920). In 1920 — 33 he worked at the Institute of Physical Chemistry and Electrochemistry (Berlin — Dahlem) and in 1927 —33 also at the University of Berlin, in 1933 —45 at Farbenindustrie, in 1945 —48 he was professor at the technical university (Berlin — Charlottenburg), and in 1949 —68 at New York University.
His research concerned solid-state physics, atomic and nuclear physics, mass spectroscopy, neutron and X-ray diffraction, and radiation physics. He invented the scintillation counter (1947) and neutron radiography (1948). He studied X-rays, the interaction of radiation with matter, resonance effects in atomic scattering, the fluorescence of solids and liquids, photoconductivity, paramagnetic resonance, polarisation and the dynamics of excitons.