December 22, 2004

Remembering Dale Sayers

On November 25, 2004, Dale Sayers, a founder of the extended x-ray absorption fine structure (EXAFS) technique and a prominent NSLS user and advisor, passed away from complications due to a heart attack. He was 60 years old. He is remembered for his immense impact on NSLS science and operations, and his commitment to the field of synchrotron science.

Dale Sayers

Dale’s part in developing EXAFS began in 1968 when he was a graduate student at the University of Washington. He was a student of Edward Stern, a UW faculty member and a consultant for the Boeing Scientific Research Laboratories (BSRL) in Seattle. Stern knew BSRL researcher Farrel Lytle and learned of his work on what would be the early theory of EXAFS. He decided that further work on the subject would be a good thesis project for Dale.

Dale began working with Lytle at his laboratory, measuring the EXAFS of various materials. By the end of the 1970 spring semester, the major parts of the theory were established, but one task was left: determining how to obtain structural information from the EXAFS equation they had formulated. The three decided that inverting the equation would be the way, and, in 1971, Dale tried applying the Fourier integral theorem to the equation. Success!

In a 1999 Journal of Synchrotron Radiation paper, Lytle wrote, “In a defining moment, I can still visualize Dale’s excitement as he ran down the hall to greet me with the first plot of the first Fourier transform of the EXAFS function of germanium!” The EXAFS technique is now used at every synchrotron across the globe.

From left, Edward Stern, Dale Sayers, and Farrel Lytle accept the American Crystallographic Association’s Bertram Warren Award in 1979, for their development of EXAFS.

During his time as a NSLS user, beginning in the early days of the facility, Dale was a physicist with the North Carolina State University (NCSU) but spent a great deal of time here. He was the chair of the NSLS Users Executive Committee in the early 1980’s, at a time when the NSLS was an “unrefined” scientific workplace, and often a difficult environment in which to perform research. Dale established trust between the NSLS and the user community, culminating in an excellent users’ meeting in 1985 that included an especially memorable dinner event. He also chaired the UEC in 1987 and ’88.

Dale’s work at the NSLS led him to establish and operate beamline X11A. Under his leadership, X11A has been one of the most scientifically productive beamlines at the NSLS. He established a participating research team (PRT) at X11 (the longest-lived PRT beamline) and was its spokesperson from 1983 until 2001.

In the 1990’s, Dale initiated a mammography project at the NSLS, working with former NSLS staff physicists Bill Thomlinson and Dean Chapman, and current NSLS physicist Zhong Zhong. The project led to the development of diffraction-enhanced imaging (DEI), a technique now used around the world to image bone and soft tissue in a way not possible using conventional x-rays. Dale became the co-spokesperson for beamline X15A after a dedicated DEI system was established there in 1998. He was leading efforts to apply DEI to a clinical setting and, for the past few years, had been working with graduate students Dean Connor and Miklos Kiss to characterize bone and reconstruct DEI images using computerized tomography (CT).

Dale “test drives” a human diffractometer at beamline X17 in 1993.

While Dale was renowned internationally for his research, his influence extended far beyond raw science. Astute and determined, he was committed to the successful operation of synchrotron facilities and the success of the field of synchrotron radiation research. This led him to become a trusted advisor to many facilities, and he sat on many scientific advisory committees.

Dale was known as a tough, yet fair, advisor, but his personal experiences were filled with laughter and frequent interactions with family, friends, and colleagues. He enjoyed traveling abroad with his wife, Anne, and did so often.

Dale earned his bachelor’s degree from the University of California at Berkeley, his master’s and Ph.D. degrees at the University of Washington, and then joined the NCSU physics department in 1976. He received many awards over the course of his career, including the American Crystallographic Association’s Bertram Warren Award, Case Western Reserve University’s Centennial Scholar Award, and the Outstanding Achievement Award of the International XAFS Society.

ARTICLE BY: Laura Mgrdichian

CONTRIBUTIONS BY: Bill Thomlinson, Zhong Zhong, and Kumi Pandya