Virginia Tech Postdoctoral Associate Receives Jefferson Science Associate Thesis Prize

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NEWPORT NEWS—A doctoral dissertation describing how the measurement of “neutron skins” at the atomic level relates to the formation and structure of neutron stars recently earned Devi Lal Adhikari the prestigious annual Jefferson Science Associates (JSA) Thesis Prize. His thesis is titled, “Neutron Skin Measurement of 208Pb Using Parity-Violating Electron Scattering.”

The JSA Thesis Prize was established in 1999 to reward top Ph.D. thesis on research related to Jefferson Lab science. It is funded by the JSA Initiatives Fund program, which supports programs, initiatives, and activities that further the scientific outreach and promote the science, education, and technology missions of Jefferson Lab, and which benefits the laboratory’s user community.

To provide some background, a nucleus consists of neutrons and protons, with smaller, lighter nuclei containing roughly equal numbers of both particles. As the size of the nucleus increases, however, so does the number of neutrons relative to protons. It is commonly understood—but never precisely measured—that those excess neutrons for a layer of pure neutron matter on the surface of the nucleus are referred to as the “neutron skin.”

Since 2016, Adhikari has been helping to run two experiments at Jefferson Lab—called PREX-II and CREX—to probe and measure the distribution of neutrons in heavier nuclei. Both were conducted using the lab’s powerful Continuous Electron Beam Accelerator Facility (CEBAF).

Interestingly, the PREX-II measurement also correlates to the formation and structure of neutron stars—the collapsed cores of supergiant suns—even though they are 18 orders of magnitude larger than the atomic nuclei.

“Both of them are neutron-rich and they have a mathematical correlation,” said Adhikari in a press release. “So, the measurement that we make in the neutron rich nucleus can give us an idea of that giant neutron star.”

The announcement of Adhikari’s winning thesis was made by the Jefferson Lab Users Organization (JLUO).

“Every year, the JLUO board is confronted with the daunting task of selecting the best graduate student from a large pool of truly outstanding submissions,” said JLUO Chair Carlos Munoz-Camacho. “This year was no exception, and we should all be proud of the extremely high quality of young researchers. Devi Lal Adhikari won the prize for his high-impact results that connect the structure of nuclei investigated at Jefferson Lab with the physics of stellar objects such as neutron stars. The committee was impressed by Adhikari’s personal contribution to two challenging experiments—PREX-II and CREX—that ran in Hall A and that are at the origin of his exciting findings. The JLUO board wholeheartedly congratulates Adhikari for his great accomplishment.”

Candidates are nominated by senior scientists with the support of three letters of recommendation. Judges weigh four criteria: the quality of the written work, the student’s contribution to the research, the work’s impact on the field of physics, and service—how the work contributes to Jefferson Lab or other experiments.