Obituary of Stanley Hanna (1920-2012)
DOI: 10.1063/PT.4.1477
Stanley Sweet Hanna, who retired from the physics faculty of Stanford University in 1991, died on December 27, 2012 in Palo Alto. Stan was born in Sagaing, Burma (Myanmar) on May 17, 1920, the third child of missionary parents. At age fourteen he was sent to the United States for his education. He attended Denison University where he was elected to Phi Beta Kappa and graduated in 1941 with a Bachelor of Arts degree.
Stan then entered the graduate school at Johns Hopkins University, but during WWII his graduate training was interrupted while he served one year in the US Army at the Los Alamos Laboratory. After returning to his graduate study he earned a Ph.D. in physics in 1947. He became an instructor and later an Assistant Professor until 1955, when joined the research faculty staff at the Argonne National laboratory. In 1958-59 he spent a year at Oxford University as a Guggenheim Fellow, and then in 1963 joined the physics faculty at Stanford University where he taught and conducted research for the rest of his career.
Stan’s work was characterized by his outstanding capacity for innovation in his experiments. This was especially evident in his use of the Mossbauer effect to discover the nuclear Zeeman spectrum in 57Fe. His interpretation of this spectrum lead to a determination of the magnetic moment of the excited state of this nucleus, and gave the direction and magnitude of the hyperfine field which was unexpectedly opposite to the direction of the magnetic field. He obtained the first nuclear Zeeman spectrum of 119Sn, a ‘nonmagnetic’ atom in a magnetic alloy. Stan extended his study of hyperfine fields to implanted ions as well as free ions. He utilized large decoupling fields to preserve nuclear alignment and to measure nuclear g-factors.
He pioneered the use of large NaI crystals to study gamma rays from giant resonances in a number of nuclei. These studies resulted in determining resonant structure of intermediate width, constancy of the angular distributions, detection of quadrupole radiation, and isospin splitting in the resonances. He introduced the use of polarized protons in these experiments to obtain definitive measurements of electric quadrupole and dipole resonances as well as their configurations.
In his study of analog states, Stan was the first to observe (delta)T=2 isospin resonances and their radiative decay. He developed the method of producing polarized beta-emitting nuclei by use of a polarized gas jet target in a nuclear reaction. He used the pion charge-exchange reaction to excite analogue giant resonances in light nuclei and to show convincingly the existence of isospin splitting.
Producing such a large number and variety of essential contributions clearly distinguished Stan as a leader in the field of nuclear physics. This was recognized worldwide by his many awards from, and visiting professorships at, universities and institutions abroad. He received a Guggenheim Fellowship for a year of study at Oxford University in 1958; the Alexander von Humboldt Award from the Max Planck Institute in Heidelberg, Germany in 1977, and again in 1989 from Marburg University, Marburg, Germany. He was a visiting professor at the Weizmann Institute of Science, Rehovoth, Israel in 1969-70; Osaka University, Japan in 1972; the Universities of Canberra and Melbourne, Australia in 1975; Centre de Recherches Nucleaires, Strasbourg, France in 1984; and was Honorary Visiting Professor at the University of Manchester, England in 1989.
He presented over one hundred invited lectures at conferences that were based on 167 articles published in refereed journals. His abiding leadership was recognized when he was elected Chairman of the Nuclear Physics Division of the American Physical Society (APS) in 1976-77. He also served on the Executive Committee of APS in 1979-82.
The appreciation that Stan’s colleagues and graduate students had for him was expressed during the retirement symposium held in honor of his 70th birthday at Stanford University in 1991. It was attended by many of his long-time colleagues and many of his 55 graduate students, some of whom presented lectures. A zeitschrift based on the symposium that included other relevant papers as well was published in 1994.
Throughout his long career, Stan gave generously of himself to all with whom he interacted. As an adviser, model, confidant, and friend, he dealt with each as an individual, sensing strength, repairing weaknesses, giving encouragement when needed and enthusiastic praise for success. Stan, having thus touched the lives and careers of so many students and colleagues, has left with a lasting legacy to be cherished by all who knew him.
