Four Argonne physicists named APS fellows

December 18, 2012

ARGONNE, Ill. – Four scientists at the U.S. Department of Energy’s Argonne National Laboratory have been named fellows of the American Physical Society for 2012.

Physicists John Arrington, Glenn Decker, Marcel Demarteau and Stephen Southworth were recognized for their "exceptional contributions to physics."

Arrington’s research uses electron, positron and muon scattering from protons and nuclei to obtain a detailed understanding of the quark sub-structure. His measurements of nuclei focus on probing small, high-density clusters of protons and neutrons.

"The fundamental question I’ve sought to address," he said, "is whether the internal structure of protons and neutrons is changed when they are found within these super-dense clusters in a nucleus."

His proton structure studies involve using precise electron-scattering data to isolate small differences between the up- and down-quark distributions in the proton and the even smaller contribution of strange quarks. His experiments, including comparisons of electron-proton and positron-proton scattering, provide improved understanding of small but crucial corrections to these measurements. His newest project involves comparing electron and muon scattering to help understand the "proton radius puzzle," an inconsistency between ultra-precise atomic physics measurements that suggests the possibility of an unexpected difference between electron and muon interactions.

Decker’s citation recognizes his "outstanding contributions to the design, commissioning, and enhancement of synchrotron light sources, and for innovative developments in the field of particle beam diagnostics."

Decker also developed an accelerator alignment technique that reduces stray radiation background signals from beam position monitors, an improvement that has come to be known as the known as the "Decker distortion."

Decker served as the Advanced Photon Source storage ring manager during the facility’s construction. He defined many of the technical specifications for ring components, including the structure of the orbit correction systems. He led the team that successfully commissioned the APS linear accelerator, positron accumulator ring, booster, associated transport lines and storage ring.

Demarteau was recognized for his work at Fermilab, where he was a member of the Dzero experiment, one of the two collider experiments at the Tevatron collider. With the initial data set of the experiment, he carried out one of the most precise measurements of the mass of the W-boson, a fundamental particle, as well as studied the properties of the electroweak force. He was also instrumental in the development and construction of new generations of silicon detectors that enable tagging long-lived quarks, which have been crucial in the search for the recently discovered Higgs boson.

During his time at Argonne, Demarteau has expanded his role to be a strong advocate for a reinvestment in the development of new detector technologies.

"I really believe that the field of high-energy physics and society in general needs a renewed dedication to the development of new technologies to radically re-invent some mainstream technologies," he said. "Argonne is uniquely positioned to do this, both for fundamental science and for society at large."

Southworth’s work makes use of the X-ray beams produced at facilities such as the Argonne’s Advanced Photon Source and the Linac Coherent Light Source at the SLAC National Accelerator Laboratory.

"The X-rays are used for a wide range of scientific fields, but my research has focused on experiments that demonstrate how X-rays interact with atoms and small molecules," Southworth said.  

The American Physical Society citation specifically noted Southworth’s breakthroughs in characterizing the extremely fast responses of atoms and molecules to X-ray pulses.

"There’s a lot of research now being done at the femtosecond time scale, which is one-quadrillionth of a second," he said. "We have a better step-by-step understanding than ever before of how atoms respond to very short and intense X-rays."

About Argonne

The U.S. Department of Energy's Argonne National Laboratory seeks solutions to pressing national problems in science and technology. The nation’s first national laboratory, Argonne conducts leading-edge basic and applied scientific research in virtually every scientific discipline. Argonne researchers work closely with researchers from hundreds of companies, universities, and federal, state and municipal agencies to help them solve their specific problems, advance America’s scientific leadership and prepare the nation for a better future. With employees from more than 60 nations, Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy’s Office of Science.