Obituary of Mitio Inokuti

Mitio Inokuti, Physicist, scholar, mentor

Mitio Inokuti, an eminent radiation physicist, died on June 4, 2009. After his formal education at The University of Tokyo (Ph.D. 1962), and a year at Northwestern University, he spent his entire career from 1963 at Argonne National Laboratory, becoming Senior Physicist in 1973 and later Manager of the Molecular Radiation Physics Program. After retirement in 1995, he continued in a special appointment in the Physics Division, remaining active till his death. He published over 200 research papers and over 70 educational articles on scientific topics, was a Fellow of the American Physical Society and the Institute of Physics (London), and received (in 1990) The University of Chicago Award for Distinguished Performance.

Mitio set himself firmly in the tradition of Bethe and his own mentors, Ugo Fano and Robert Platzman, in grounding radiation-matter interactions in the quantum physics of atoms, molecules and radiation. Given his broad and solid understanding of atomic physics and collision theory, and his thorough training at Tokyo in applied physics and quantum chemistry, radiation physics was a perfect match to his talents.

With its many applications in medicine and astronomy, radiation physics draws upon a vast amount of data: electron-atom/molecule collisions, ion-atom collisions, and spectroscopy over a broad range of wavelengths. Some of this data is difficult to obtain and sometimes of uncertain reliability. As in a famous Reviews of Modern Physics article he wrote in 1971, Mitio emphasized firm principles and brought a unique point of view to the field through the insight that general theoretical constraints (such as asymptotic limits and sum rules) could be used to test the soundness of measurements. This theme runs throughout his publications and can be attributed to the influence of Kubo, who was one of his teachers in Tokyo.

Mitio was a mentor to many students and colleagues. He was a teacher in the larger sense and devoted considerable effort to review articles. He was frequently called upon for summary talks at conferences. His enthusiasm, high standards, and wealth of ideas made him an ideal coworker and many a collaboration became a tutorial, a master class in physics. His colleagues at Argonne can attribute much of their understanding of radiation physics to his tutorial of Heitler’s classic book “The Quantum Theory of Radiation”. Many in the community were eagerly awaiting the book, “Principles of Radiation Physics”, that he was working on till the very end.

He felt a great responsibility to the scientific community and served as a referee for numerous journals. He was proud and happy to be in the select group initially chosen as Outstanding Referees by Physical Review. He was on the Editorial Board of Advances in Atomic, Molecular, and Optical Physics, a contributing editor for Comments on Atomic and Molecular Physics from its inception, and was Associate Editor of the Journal of Applied Physics from 1996. Even when he was very ill, a prevailing concern of his was keeping up with his editorial duties. He was particularly proud of his contributions to the ICRU (International Commission on Radiation Units and Measurements), especially as their Scientific Editor from 2001. The quality of the tabulations now available to the radiological community is, in large measure, attributable to his efforts. The accent on accuracy and clarity was characteristic of him as a man and a physicist.

His approach to life made him the perfect companion in many ways. At the lunch table, we were regaled with historical anecdotes of Einstein – whose every biography he had read. As an inveterate photographer, he documented many scientific and social events, and shared his keen observations with all. Many remarkable scenes captured on his professional travels, from Alpine scenes to alley cats in Barcelona, appeared as background displays on his computers. Given his Japanese sensibilities, we delighted in some of the vignettes he presented of that culture and his life. He had been a boyhood friend of the present emperor of Japan, and they had been evacuated together to outside Tokyo during WW II. The emperor is himself a scientist, an ichthyologist who has published papers in scientific journals. Mitio told once of how the emperor valued the native knowledge that fishermen have from their generations-long experience with the animals, urging scientists to draw upon that as well to present in their scholarly publications. This extends to how the fish tastes and whether it is good to eat!

The community has lost a true scientist, scholar and mentor. We will miss him dearly.