Dr. Priyashree Roy, University of Michigan Physics Research Fellow, is the recipient of the 2016 Jefferson Science Associates (JSA) Thesis Prize for her doctoral thesis. Dr. Roy spent five years at the Thomas Jefferson National Accelerator Facility and Florida State University to extract a set of polarization observables which are crucial to understanding the excited states of the proton. She is now at the University of Michigan Department of Physics to continue the study of this elementary nuclear particle, which is one of the essential ingredients of matter.
Dr. Roy’s prized Ph.D. thesis title was, “Measurement of Polarization Observables in Vector Meson Photoproduction using a Transversely-Polarized Frozen-Spin Target and Polarized Protons at CLAS, Jefferson Lab.” The JSA Thesis Prize is awarded annually for the best Ph.D. student thesis including theoretical and experimental work on many different topics under study at the Jefferson Lab.
Dr. Roy's thesis research was in the field of baryon spectroscopy. By understanding the baryon spectrum one can get an insight into the effective degrees of freedom in baryons such as the proton. However, unlike atomic states, the excited states of baryons are broad and overlapping which makes it quite difficult to identify these states. Researchers need a set of ‘polarization observables’ to disentangle them. These observables become accessible in polarized measurements. Dr. Roy studied the data which was collected using a polarized photon beam, with energies up to 6 GeV, incident on a polarized proton source (frozen beads of doped-butanol). One of the several possible outcomes of the proton-photon interactions was that the proton attained an excited state which quickly de-excited to the lowest energy state via emission of various kinds of final-state particles. She studied reactions with ω meson or two pions in the final-states and extracted 13 polarization observables. These observables, many of which are first-time measurements, are immensely useful in revealing the excited states contributing to these two reactions with minimal ambiguities.
Dr. Roy is currently building a liquid hydrogen target for the Muon Proton Scattering Experiment (MUSE) which will take place in Switzerland starting in 2018 with direction from her research advisor, U-M Physics Professor Wolfgang Lorenzon. The MUSE experiment aims at resolving the mystery pertaining to the radius of the proton, a puzzle that has attracted much attention in the scientific community. This will be the first experiment to simultaneously scatter electrons and muons from protons and provide researchers with the proton electric radius as measured by both leptonic probes. The simultaneous measurements will allow them to compare the two results with a good control on the systematic uncertainties and hopefully resolve the proton radius conundrum.
This summer, Dr. Roy is dedicating time towards achieving a successful design of the MUSE liquid hydrogen cryotarget system. The U-M cryotarget group is responsible for the design, fabrication and maintenance of the MUSE cryotarget. She is fabricating many prototypes of the target cell in Professor Lorenzon’s lab and testing them to optimize the target cell fabrication technique. Dr. Roy also plans to become involved in the development of the MUSE data analysis software in parallel.
The Thesis Prize is awarded annually for the best Ph.D. student thesis on research related to Jefferson Lab science and includes a $2,500 cash award and a commemorative plaque. In addition, the recipient presents his or her work during a session at the Jefferson Lab Users Group’s annual meeting. Four areas are considered in rating the submitted theses: the 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 Jefferson Lab or other experiments).
The Thesis Prize was established in 1999 by the Southeastern Universities Research Association, the predecessor management and operating contractor for Jefferson Lab. It is one of many projects supported by the JSA Initiatives Fund, a program funded by the JSA owners (SURA and CSC/ATD) to support efforts that further the scientific outreach and promote the science, education and technology missions of Jefferson Lab and the Lab’s user community. The annual commitment of $0.5 Million is administered by the JSA Programs Committee. For more information about the program, see http://www.jsallc.org/IF/IFIndex.html.
Jefferson Lab is managed and operated by Jefferson Science Associates, LLC, for the Department of Energy's Office of Science.