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In Memoriam: Andrew Sessler, Former Laboratory Director, Acclaimed Physicist and Humanitarian

Andy Sessler (1928-2014)

Andy Sessler (1928-2014)

Andrew Marienhoff Sessler passed away April 17, 2014, following a long illness. He was 85. The former director of Lawrence Berkeley National Laboratory was a visionary in accelerator and energy sciences, and was instrumental in the worldwide effort to liberate scientists suffering from political oppression. Born on December 11, 1928, Sessler showed an early talent for science, and was one of the first Westinghouse Talent Search finalists.  He received a B.A. in mathematics from Harvard and a Ph.D. in physics from Columbia University.  He was in the first group of National Science Foundation post-docs, working at Cornell University with Hans Bethe. From 1954 to 1959 he was on the faculty at Ohio State, after which he joined the Lawrence Radiation Laboratory, now the Lawrence Berkeley National Laboratory.  He spent the rest of his career there and served as the Laboratory’s third director from 1973 to 1980.

His many honors included the Ernest Orlando Lawrence Award in 1970, which is the U.S Department of Energy’s highest scientific recognition;  the American Physical Society (APS) Dwight Nicholson Medal in 1995; the APS Robert R. Wilson Prize in 1997; and the Enrico Fermi Award in early 2014.  He was APS president in 1998.

Sessler made several key contributions to physics and accelerator science.  His paper with J. Emery in 1960, together with a contemporaneous competing paper from Anderson et al., is generally acknowledged as the first to predict the superfluid transition of helium-3.  His contributions to accelerator science, which began with his association with the Midwestern Universities Research Association, were pivotal for developing modern high-performance accelerators. They included  a Hamiltonian-based radio-frequency acceleration theory, developing a method to produce intense circulating proton beams by stacking, which made feasible very high-luminosity proton colliders, such as CERN’s Large Hadron Collider, and a systematic study of beam instabilities at high intensity, which became the standard for all modern accelerator design. His 1981 proposal for a high-gain free electron laser (FEL) amplifier for high-power, mm wave generation, helped lay the foundation for the emergence of the era of x-ray FELs that began in 2009 with the successful start of operation of the Linac Coherent Light Source at SLAC. His basic concept for a two-beam accelerator that mixed high and low energies and currents was modified to become the Compact Linear Collider project at CERN, a candidate technology for a future multi-TeV electron-positron linear collider.

As director of the Lawrence Berkeley National Laboratory, Sessler ushered in a new era of research on energy efficiency and sustainable energy technology by establishing what would become the Energy and Environment Division, the first such group at any of the national laboratories. This was instrumental in transforming the mission of national laboratories from science labs to science, engineering, and energy labs.  Under Sessler’s leadership, Lawrence Berkeley National Laboratory grew to its largest size ever, with more than 5,000 employees, and expanded beyond its leading roles in physics, chemistry and biology to its current multi-program  efforts.

Said Paul Alivisatos, the current director of the Lawrence Berkeley National Laboratory, “Andy Sessler changed the face and character of our Laboratory. He successfully made the case for science to aid our country during its first energy crisis and helped establish the Lab’s efforts that brought about important technologies and standards that have improved the way we conserve and consume energy.”

In addition to his ground-breaking work in particle accelerator and beam physics, and his leadership in directing the scientific research landscape toward new horizons in sustainable energy and the environment, Sessler was also an acclaimed humanitarian and public advocate for scientific freedom. His activities at the American Physical Society (APS) over many years helped transform its focus on “physics” to include “physics and society,” with attention to national funding, patterns of employment, science education at all levels, societal issues involving physics, informing the public, international affairs, arms control, and, in particular, the human rights of his physics colleagues.

Intensely concerned about human rights, Sessler focused on scientists caught in political situations beyond their control.  He wrote letters in support of dissidents in the Soviet Union and other countries. He was active on boards and committees that pursued human rights activities within many organizations, including the American Physical Society, the National Academy of Sciences, the New York Academy of Sciences, the Committee of Concerned Scientists, the Union of Concerned Scientists, and Amnesty International. He donated large sums of money to charities including Doctors without Borders, Berkeley Food and Housing, and FINCA (a global charitable microfinance organization).

Sessler was instrumental in initiating the APS Committee on International Freedom of Scientists and raising funds to endow the APS Sakharov Prize for Human Rights.  Along with his colleague Moishe Pripstein, he was a co-founder of Scientists for Sakharov, Orlov, and Sharansky (SOS).  Protests by SOS and others led to the release of these Soviet dissidents and to an overall increase in pressure by the scientific community in solidarity with their politically oppressed colleagues.  He also was one of the principal organizers of the “good-faith witness” exchange, which earned the release of Elena Bonner, the wife of Andrei Sakharov, from the Soviet Union to the U.S. to receive medical care.

Sessler was an avid outdoor person and loved sharing physical activities, such as swimming, rowing, skiing, and bicycling, with family and friends. He was a mentor to many younger colleagues and to many his own age who learned much from him.  Later in life, he could be found jogging with others during lunchtime, sharing jokes and solving physics challenges. Just as he loved sharing the outdoors, he loved sharing knowledge and seldom wrote scientific papers alone.  A long-time friend and colleague expressed a sentiment shared by many who knew Sessler: “If there was ever a scientist for whom the physics community was at the center of his life and work, it was Andy Sessler.”

Sessler is survived by three children and six grandchildren. No public memorial is planned. Those wishing to make donations in his name are encouraged to consider the Mary and David Sessler Endowment Fund, supporting graduate students in physics through the University Relations-Gift Processing, 2080 Addison Street, Berkeley, CA 94720-4200;  Earthjustice; and Amnesty International USA.


This article was prepared by Andy Sessler’s longtime friends and colleagues Robert Budnitz, Kwang-Je Kim and Herman Winick.

Additional Information

To learn more about Andy Sessler’s years as Laboratory Director, go here