Physics student earns statewide accolade for positron research

Tuesday, Dec 03, 2024 • Greg Pederson :

Pratyanik Sau, a senior in physics, left, with project collaborator Nicholas Hancock, a senior in mathematics.

An undergraduate student in physics at The University of Texas at Arlington earned a top award from the Texas Section of the American Physical Society for his research using positrons to study the electronic properties of graphene.

Pratyanik Sau, a senior who will graduate in December with a B.S. in physics and a dual minor in data science and mathematics, won the Outstanding Undergraduate Student Oral Presentation Award at the Fall 2024 Joint Meeting of the Texas Section of the APS, the Texas Section of the AAPT (American Association of Physics Teachers), and Zone 13 of SPS (Society of Physics Students) at SMU in October.

Sau is a member of the physics department’s Positron Physics Group. His faculty mentors are Alex Weiss and Ali Koymen, professors of physics, and Varghese Chirayath, assistant professor of research. Nicholas Hancock, a senior majoring in mathematics with a dual minor in physics and computer science, is second author and co-collaborator on the project.

Sau’s presentation was titled “Positron Impact Induced Secondary Electron Spectra of Graphene and Graphite”. The project involves the study of two-dimensional (2D) materials, which are only one or two atoms thick but are wider in every other direction. Scientists work with both naturally occurring 2D materials, like graphene, and materials synthesized in labs. Graphene, a form of ultra-strong carbon, was the first 2D material to be discovered, in 2004

“Characterizing surfaces of 2D materials is difficult since most of the conventional methods produce signals from the 2D materials and the underlying substrate on which the 2D material is grown,” Sau said.

A positron is the antiparticle to the electron and has the same mass as the electron but opposite charge. The team implanted low-energy positrons in graphene, which resulted in the ejection of electrons from the graphene, thus revealing its electronic properties.

“In this work, we reported a way to analyze the experimental data and obtain the distribution of the energy of positron impact-induced electrons,” Sau said. “We compared the results obtained from graphene to its 3D counterpart, graphite, and to the copper substrate.”

Sau said that the information gained from the research can be useful in designing walls of particle accelerators or future fusion reactors, where it is necessary to lower the background due to secondary electron yield.

“I would like to acknowledge and extend my sincere appreciation to Dr. Chirayath, without whom this would not have been possible,” Sau said. “Aside from being my supervisor on this project, he has been an excellent mentor and friend. His extreme dedication and passion for research have significantly motivated me to pursue my research aspirations.

“Nicholas Hancock also contributed extensively to this project. He is an extremely motivated and inquisitive research student and has a natural inclination towards mathematics in general. I would like to thank him and acknowledge his contributions to the culmination of this project.

“I would also like to extend my sincere gratitude towards my other supervisors on this project, Dr. Weiss and Dr. Koymen. Their contributions to the field of positron physics are unmatched. Next, I would like to acknowledge Ilker Parmaksiz, a Ph.D. student working with Dr. Jonathan Asaadi's group, who is also preparing to defend his thesis and graduate this semester, for his significant contributions to the GEANT 4 simulations in this project.”

The corresponding paper resulting from the research will be submitted to an academic journal for publication.

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