Very rare lithograph by Leo Vartanian commemorating the CP-1 nuclear reactor. Moderator graphite from the historic reactor was ground up to make the ink in which the portraits of physicists Leo Szilard, Arthur Compton, Enrico Fermi, and Eugene Wigner were rendered. Prints were distributed by Argonne National Laboratory to honor long and illustrious careers. The ink is not detectably radioactive. The dimensions are 17″ by 22″   It is estimated that only 43 copies were made and distributed.