Biographical Memoirs Volume 84 (2004) / Chapter Skim
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Pages 321-348
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From page 321... ...
Over the course of his scientific career, which spanned six decades, he made fundamental contributions to a wide- ranging area of basic research, including atomic, nuclear, and particle physics. A conscientious and meticulous teacher, Sachs guided the research of several graduates from the University of Wisconsin and the University of Chicago who have made their own mark in research.
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From page 322... ...
He was recognized for his contributions to questions relating to national and international energy policies, for his services to high-energy physics panels, and for his successful efforts in creating the Division of Particles and Fields. He served as associate laboratory director at Argonne National Laboratory (1964-68)
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R O B E R T G R E E N S A C H S 323 seven siblings from his father's second marriage after the death of his first wife. Bob's mother, Anna Green, was the daughter of an upper-middle-class Jewish family in Richmond, Virginia.
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. At the time, the results were of interest mainly in determining neutron crosssections from measurements on molecular gases, but later they played a vital role in the study and analysis of neutron dynamics in gas-cooled reactors that became a part of the Atomic Energy Commission program.
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R O B E R T G R E E N S A C H S 325 project on crystal rectifiers. In 1943 he moved to Aberdeen Proving Ground in Maryland to become the chief of the air blast section of the terminal ballistics branch of the Ballistic Research Laboratory (BRL)
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An extract from this report appeared in the Bulletin of Atomic Scientists.2 At the beginning of 1946 Sachs joined the University of Chicago's Metallurgical Laboratory to work on the physics of a gas-cooled BeO, ceramic-moderated reactor for electric power generation, proposed by Farrington Daniels and hence known as Daniels Pile. When the laboratory became Argonne National Laboratory on July 1, 1946, and was transferred to the Atomic Energy Commission, Sachs was appointed director of the Theoretical Physics Division.
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Soon students graduating from Wisconsin found themselves to be leaders in Atomic Energy Commission projects and in nuclear engineering programs at Argonne National Laboratory as well as in academic positions throughout the country. The course on nuclear theory led to his writing a textbook
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Sachs's first seminal paper in nuclear physics was published before he joined the faculty at the University of Wisconsin. The paper, "Magnetic Moments of Light Nuclei" (1946)
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This was long before pi mesons were established experimentally. Persuaded by Fermi not to concentrate on a specific model, he developed a general phenomenological theory of exchange currents in nuclei (1948)
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This was the time in the 1950s when the pioneering experiments of Robert Hofstadter on electron-neutron scattering raised fundamental questions regarding the physical interpretation of the electromagnetic form factors and their physical interpretation in terms of charge and magnetic moment distribution inside the nucleon. The conventional Dirac and Pauli form factors had led to a paradoxical result in the interpretation of the measured electron-neutron interaction.8 In a paper that had strong impact, Sachs, along with F
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From page 331... ...
-- have presented a great challenge to particle theory. The invariance of interactions under their combined operation, known as the CPT theorem, is regarded as one of the sacred principles of theoretical physics, since it is based on some very general principles, such as locality, Lorentz invariance, and causality.
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From page 332... ...
covers all aspects of time-reversal invariance beginning with classical physics, extended to the quantum world of atomic and nuclear systems and finally to quantum field theories of elementary particles. In 1963 Sachs's teaching and research came to a temporary standstill when he moved to Chicago to be the associate laboratory director for high-energy physics at Argonne National Laboratory (ANL)
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, the University of Chicago, and the AEC. Earlier Roger Hilderbrand, who was Sachs's predecessor as associate laboratory director, and E
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These included, for instance, the design and construction of a 70-separated beam, a 30inch hydrogen bubble chamber, and a 40-inch heavy liquid bubble chamber. These detectors, as well as a number of new electronic particle detector systems, enabled the ZGS university-based users to make an ongoing series of notable physics contributions in topical areas such as hadron spectroscopy, exploration of quark model effects, and weak interactions.
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It was Sachs's responsibility to decide between the two. He opted for the second choice with a superconducting magnet for the bubble chamber.
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The Division of Particles and Fields was his creation. With ZGS running smoothly Sachs resigned in 1968 as the associate laboratory director to return to full-time research, teaching, and other academic responsibilities at the University of Chicago.
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The Nixon Administration, convinced of the looming energy crisis, launched a new plan under which the AEC and its national laboratories would form the core of a new energy research agency responsible for developing energy technologies and applications ranging from fossil fuels and nuclear reactors to solar energy and energy conservation. Nixon, in addition to providing the AEC an additional $100 million on energy research in fiscal year 1974, asked Dixy Lee Ray to develop a five-year national energy plan for the expenditure of $10 billion.
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From page 338... ...
One such panel was the solar energy panel that was struggling with the problem of tracking the Sun, using focusing devices to obtain useful solar energy. From his days as associate laboratory director for high-energy physics Sachs recalled the work of Roland Winston, a ZGS user from the University of Chicago.
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The extended family came together often -- for birthdays, holidays, and sometimes to sail together. "As the patriarch of a large brood," Rebecca Norris says, her father
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From page 340... ...
His enthusiasm and energy had made the department in Madison a fine place to do particle physics." Sachs was responsible for Roland Winston's outstanding career by directing him from high-energy physics to solar energy research. The summer institutes Sachs initiated at the University of Wisconsin during the years 1960-64 was a prime example of his concern for the physics community at large.
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I am particularly indebted to Rebecca Norris; Judith Crow; and Jeff, Jennifer, and Frances Sachs for providing me with Bob Sachs's family history. I have also had extensive help from many of Sachs's colleagues and associates, most particularly (in alphabetical order)
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magnetic moment of the neutron instead of the expected Dirac form factor (Phys.
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Report of the Elementary Particle Physics Panel to the Physics Survey Committee with J
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69:514-22. Magnetic moments of light nuclei.
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Wali. Electromagnetic form factors of the nucleon.
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D141:177. 1994 Is QCD consistent with quantum field theory?
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California Berkeley, Photography, Ricco-Mazzuchi
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