The Handbag Diagram Morand's work attempted to identify the lowest energies that GPDs can be used to describe the internal structure of protons and neutrons through the process of ω meson production. The experiment showed that beam energies higher than ~6 GeV are needed.

Ludyvine Morand is this year's winner of the Southeastern Universities Research Association (SURA) Thesis Prize, an annual award given by SURA in recognition of the vital role played by graduate students in the scientific mission of Jefferson Lab. Established in 1999, the prize is awarded for the best graduate student thesis and includes a stipend of $1000 and a commemorative wall plaque.

The award was presented June 15 during the annual Users Group meeting. A reading committee appointed by the JLab Users Group Board of Directors selected Morand's thesis, Measurement of Electroproduction of ω Mesons at Large Four-Momentum Transfer (English translation), from 9 submissions. Theses were graded in four major areas: quality of the written dissertation, the student's contribution to the research, the work's impact on the field of physics, and service (how the work benefits the Lab/other experiments).

"SURA is pleased with the level of competition that its annual Thesis Prize attracts, and this year is no exception. Ludyvine Morand's thesis is an excellent example of the high quality research that is being carried out at Jefferson Lab, and I congratulate her on this very significant accomplishment," says SURA President Jerry Draayer.

Morand successfully defended her thesis to earn her Ph.D. in hadronic physics from Paris University in December of last year. Her thesis was based on data from Hall B's e1-6 experimental run that took data from October 2001 to January 2002. The experiment was designed to test under which conditions the formalism of Generalized Parton Distributions, or GPDs, is valid.

"The experiment is investigating the dynamics of the quarks inside the nucleon, the position of the quarks and also their momentum," Morand explains. GPDs are mathematical functions that allow physicists to describe the internal structure of the nucleon (protons and neutrons) at high momentum transfer. However, it's not clear how high this momentum transfer has to be for a description of the reaction in terms of GPDs to be valid. In other words, there's a cut-off, or limit, below which this description is no longer applicable; Morand's work was essentially aimed at finding that lower limit.

In the experiment, a beam of electrons was sent into a hydrogen target. Morand was looking for events in which a single electron interacts with one of the three quarks of the proton (the hydrogen nucleus is made up of one proton). This interaction can produce new particles.

Morand was interested in the production of a particle called an ω meson, which is made up of two quarks. She was looking for evidence that these mesons were produced in a process illustrated by the handbag diagram (see picture), a tool physicists use to represent such interactions.

She found that ω mesons were produced at a rate five times higher than predicted by the handbag diagram mechanism. Hence, this mechanism alone did not account for all of the ω mesons produced. This showed that the ~6 GeV beam energy used in the experiment is below the lower beam energy limit at which GPDs are most appropriate for describing the internal structure of nucleons.

"On one hand, this is bad news, because we are not in the right domain yet, and at this stage, we can't go further in the structure of the nucleon with this method. But on the other hand, it tells you that something else is happening. So there is always something to learn from an experiment, even if it's not what you wanted," Morand says.

Morand is now looking for a permanent position where she can use her knowledge of nuclear physics in applied research. "I'm looking for something related to nuclear physics, but for an applied goal. Some people are using small electron accelerators to produce photons to inspect trucks for customs agencies, and others are studying the safety of nuclear power plants. These are the kinds of applications I'm interested in," she says. Morand currently lives in Villejust, France, with her husband, Christophe Jutier, another nuclear physicist who received his Ph.D. at ODU and whom she met during her first visit to Jefferson Lab while on an internship.

Front Page Image: Ludyvine Morand, 2003 SURA Thesis Prize Winner