Obituary of Philip Altick

Philip Altick died on December 1, 2008 after coronary failure during a hike with a friend in his beloved Sierra Nevada mountains. Phil earned a B.S. in Physics with Distinction from Stanford University on a Navy ROTC scholarship and served as a Midshipman and First Lieutenant in the Marine Corps. After earning a Ph.D. in Physics from the University of California, Berkeley in 1963, he joined the faculty of the University of Nevada where he spent his entire career. At that time, the university was poised for growth and Altick brought recognition and prestige to Nevada. He was honored as a Foundation Professor and as a Distinguished Faculty Member. He was a Fellow of the American Physical Society.

Phil was a pioneer in the study of electron correlations in atoms, especially of the dramatic manifestations of these correlations. In the late 1950s, the BCS theory of superconductivity showed the importance of electron correlations in infinite many-electron systems, and Gell-Mann, Brueckner and others developed techniques for their calculation. By 1960, these calculations were being extended to finite many-fermion systems in nuclei and it was in these early 1960s that Altick and Glassgold wrote an influential paper on such calculations for many-electron atoms. The random phase approximation for the electron gas was also adapted for such finite systems, making it possible to study single and multiple ionization of atoms by photons and electrons. In oscillator strength and photoionization calculations of Be, Mg, Ca, Sr and Al, Altick showed how electron correlations can change cross-sections especially near threshold by as much as factors of five.

Also in the early 1960s, the study of doubly excited states of even the simplest two-electron atom, helium, pointed to correlations between the two electrons giving rise to qualitatively significant effects such as new quantum numbers for the pair, initially called plus/minus by Fano, Cooper and Prats. Altick and Moore presented the first quantitative numerical calculations supporting these arguments. Thereby, they extended configuration interaction calculations from bound states to such resonance states with continuum character. This was a numerical realization of the very influential paper by Fano in 1961 that views such resonances as discrete states embedded in a continuum.

Phil spent a year in 1967 with Ugo Fano in Chicago, beginning a detailed analysis of singularities in the three-body Coulomb system (positive core plus two electrons), especially when one pair or all three are close together. Although in later years he himself felt that his analytical work for many years did not yield results commensurate with that effort, in parallel work he teamed very successfully with the first experimental results that were just emerging on electron impact ionization of helium with coincident detection of the two outgoing electrons. During a sabbatical stay in the early 1970s with H. Ehrhardt’s group at Kaiserslautern, and subsequently, Altick and his students matched their calculations of triply-differential (in the angles and mutual energy apportioning between the electrons) cross-sections with experimental data of that group. This long and successful collaboration was a precursor to such coincidence experiments on multiple ionization of atoms and theoretical calculations by many workers. Phil himself became involved in the early 1990s with distorted wave Born approximation calculations and their applications to Kaiserslautern data.

Particularly noteworthy was a so-called correlation factor that Phil introduced, namely a Coulomb phase term between the two electrons along with individual Coulomb waves for each in the nuclear field. In later discussions of what came to be called the Redmond phase and its incorporation into a three-body wave function by Brauner, Briggs and Klar, it became central to our understanding of correlation between two slow electrons and Phil’s work can now be seen as ahead of its time.

Phil’s style and effectiveness as a teacher are legendary, and his research was internationally regarded. He had sabbatical stays at the University of Chicago, in Germany at the Universities of Freiburg and Kaiserslautern, and in the United Kingdom at Daresbury Laboratory, Queen’s University, Belfast and University College, London. After retirement in 1995, he became involved in a scholarly role at Chautauqua and related historical events, including playing the role of Isaac Newton. A lifelong outdoor enthusiast, Phil was passionate about the treasures of the Sierra Nevada. In retirement he served at the Tahoe Environmental Research Center and helped to develop the Tahoe Rim Trail. Philip Altick was an extraordinary individual. To his family, and to colleagues who were fortunate to have known him, Phil was a beloved figure. We will remember him fondly.