Sambamurti Lecture: The Whole Story Behind a Half, The Quest to Understand the Proton's Spin

July 18, 2008

Christine Aidala

On Tuesday, July 22, the 2008 Sambamurti Lecture will be given by Christine Aidala, University of Massachusetts, Amherst, at 3:30 p.m. in the Physics Large Seminar Room, Bldg. 510. Aidala will talk on "The Whole Story Behind a Half: The Quest to Understand the Proton's Spin."

The proton is a positively charged subatomic particle which constitutes the nucleus of the ordinary hydrogen atom. Every atomic nucleus contains one or more protons. It has been known for nearly 80 years that the proton's spin is the same as the spin of the electron - a negatively charged subatomic particle that can be found either free, unattached to any atom, or bound to the nucleus of an atom. However, unlike the electron, still believed to be a point particle, the proton is known to be composite, made up of quarks and gluons, all of which have their own spin values.

Since a surprising measurement in the late 1980s revealed that the proton's subcomponents did not build up its spin as expected, scientists have maintained an ongoing quest to unravel this puzzle. As part of these worldwide efforts, the spin program at the Relativistic Heavy Ion Collider (RHIC) has been colliding high-energy beams of polarized protons since late 2001. Aidala, a member of RHIC's PHENIX experiment since the first polarized proton run, has made measurements probing both the transverse as well as the longitudinal spin structure of the proton, helping to elucidate the structure of one of the fundamental building blocks of ordinary matter.

Aidala received her B.S. degree in physics from Yale University in 1999 and her Ph.D. in high-energy nuclear physics from Columbia University in 2005. She is currently a postdoctoral research associate working for the University of Massachusetts, Amherst.

The Sambamurti Memorial Lecture was established in 1992 to commemorate the work of Aditya Sambamurti, a young BNL physicist who died of cancer in 1992 at age 31. Each year, an outstanding young physicist whose professional interests overlap those of Sambamurti is selected to deliver the lecture.

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