Paul Frederick Zweifel

Paul Frederick Zweifel
Born	(1929-06-21)June 21, 1929 New York City
Died	February 12, 2017(2017-02-12) (aged 87)
Alma mater	Duke University (PhD)
Known for	Mathematical theory of nuclear reactors
Awards	American Physical Society Fellowship (1963) Ernest Orlando Lawrence Award (1972) Guggenheim Fellowship (1974)
Scientific career
Fields	Nuclear reactor physics Radiative transfer Transport theory Statistical physics Music Theory
Institutions	Knolls Atomic Power Laboratory University of Michigan Virginia Tech
Thesis	Capture-Positron Branching Ratios  (1954)
Doctoral advisor	Eugene Greuling

Paul Frederick Zweifel (21 June 1929 – 12 February 2017) was a mathematical physicist and a prominent leader in the mathematical theory of nuclear reactors and the mathematical development of linear transport theory, a discipline that encompasses neutron transport in the core of a nuclear reactor, as well as the propagation of photons in radiative transfer.

One of his most notable accomplishments in transport theory was pioneering the use of rigorous mathematics for analytically solving the linear transport equation. He developed existence and uniqueness theorems for the neutron transport equation and investigated the spectrum of the linear transport operator under general conditions.

Early years

Paul Zweifel was born in June 21, 1929 in New York City to Dorothy and Frederick Zweifel. His family moved to Spartanburg, South Carolina. When he was fifteen, he received the Pepsi-Cola Scholarship to attend the college of his choice, Carnegie Institute of Technology (now Carnegie Mellon University), and graduated with a B.S. in Physics in 1948.

He received his Ph.D. in Physics in 1954 under the guidance of Eugene Greuling at Duke University.The title of his dissertation was Capture-Positron Branching Ratios. He was proud to be in the lineage of Ph.D. dissertation advisors starting with Josef Stefan to Ludwig Boltzmann to Paul Ehrenfest to Goerge Uhlenbeck to Emil Konopinski to E. Greuling and finally to P. F. Zweifel.

Zweifel worked at the Knolls Atomic Power Laboratory as a physicist and a manager of theoretical physics, where he did research on the theory of the slowing down and thermalization of neutrons from mid-1953 to 1958.

In 1958 he was appointed as associate professor of nuclear engineering at the University of Michigan and soon he was promoted to professor in 1960. There he began working with Kenneth M. Case, a physicist who made pioneering contributions to neutron transport theory during the Manhattan Project. Together they published a highly cited monograph, Linear Transport Theory, in 1967 on the linear Boltzmann equation. The mathematical approach of Case and Zweifel enables a more direct solution to many problems of the type analyzed by Boris Davison in his monograph Neutron Transport Theory and that of Subrahmanyan Chandrasekhar in his treatise Radiative Transfer.

In 1968 Paul became a Professor of Physics at Virginia Tech in Blacksburg and three years later was appointed as University Distinguished Professor, the highest distinction a professor can attain there.

Organizer of scientific meetings and founding editor of a new journal

During a sabbatical year from the University of Michigan spent as a Visiting Professor at the Middle East Technical University in 1964-1965, Paul and physicist Erdal İnönü organized a two-week NATO Advanced Study Institute on Transport Theory held in Ankara, Turkey.The conference featured six established senior faculty from the United States, Germany, and Yugoslavia and was attended by junior faculty and advanced graduate students who spoke about their dissertation projects. The proceedings, edited by the conference organizers, were published in Developments in Transport Theory.

In 1969 Paul, along with Robert Erdmann and Charles Siewert, founded a series of conferences that have become known as the International Conference on Transport Theory or ICTT meetings. The conferences continue to bring together experts in mathematical and applied transport theory from all parts of the world. As of 2024 there have been 27 meetings — none affiliated with any professional society — that were held in the United States, Italy, China, Brazil, Sweden, Russia, England, Hungary and France; Paul hosted six of the conferences in Blacksburg. The journal Transport Theory and Statistical Physics or TTSP, with Paul as its founding editor from 1971 until 1981, has published the proceedings of many ICTT meetings; the journal was re-titled in 2014 to the Journal of Computational and Theoretical Transport in recognition of the growing popularity of numerical methods in transport theory.

Publications

Paul Zwelfel published extensively in a variety of professional and nonprofessional fields, especially in reactor physics and neutron scattering, transport theory, and other mathematical physics problems including statistical physics.

Although he began his career in the field of nuclear reactors, his interests evolved to mathematical physics, becoming a professional dedicated to both practical and theoretical aspects of neutron transport and radiative transfer. He also published a significant number of technical papers in other areas, especially on the theory of music.

He was the Ph. D. advisor of Joel H. Ferziger whose dissertation was "The Theory of Neutron Slowing Down in Nuclear Reactors. Later the authors turned that into a book of the same title and Paul wrote a textbook entitled Reactor Physics.

Professional honors

In 1972 he received from the United States Department of Energy an Ernest Orlando Lawrence Award. In 1974 he received a John Simon Guggenheim Foundation Fellowship. He was a Fellow of the American Physical Society since 1963, and had an obituary published in Physics Today.

Later years

Paul Zweifel retired from Virginia Tech in 1996 but continued to publish professionally until 2014. Because he studied music beginning when he was four years old, took voice lessons as a youngster, and later performed as a vocalist, he taught an opera course at Virginia Tech after his retirement. He also established a business specialized in creating supertitles for opera companies nationwide. He and his wife supported Virginia Tech’s Moss Arts Center and endowed a scholarship to enable music students to participate in summer music festivals and professional development workshops.