CHARLES JUI portrait
  • Professor, Physics And Astronomy

Research Summary

I study the properties of ultrahigh energy cosmic rays (UHECR). I was a senior member (and acting PI of the Utah group) of the High Resolution Fly's Eye (HiRes) Experiment. The HiRes group published the first observation of the GZK Cut-off in the cosmic ray spectrum predicted in 1965. My analysis of HiRes data was the primary contribution to this discovery. Currently I am PI of the Utah group on the Telescope Array (TA) experiment, continuing the study of UHECR with upgraded detectors.


  • B.Sc., Physics, University of Ottawa
  • M.S., Physics, Stanford University
  • Ph.D., Physics / particle physics, Stanford University. Project: The MEGA experiment



I am a professor of Physics. I did my undergraduate work at University of Ottawa, Canada. I received my Ph.D. in particle physics from Stanford, on experiment in Los Alamos that searched for lepton-family number violation in decay of mu particles. My brief post-doc years were spent working on the Large Electron-Positron Collider (LEP) at the European Center for Particle Physics (CERN) in Geneva, where I worked on the OPAL experiment and focused on the study of quantum chromodynamics (QCD) of 4 jet events. University of Utah hired me as an assistant professor in the Department of Physics where I joined the High-Resolution Fly’s Eye (HiRes: project studying the highest energy cosmic rays. I became the acting Principal Investigator of the Utah HiRes group in 2002. In 2008, the HiRes group published the first observation of the Greisen-Zatsepin-K’uzmin cut-off in the cosmic ray spectrum predicted (in 1965) from the turn-on of interactions between the Cosmic Microwave Background and cosmic protons above the energy of ~6 EeV. The analysis that was the primary contributor to this discovery was done by me and my graduate students and post-docs. As part of the HiRes project I have also directed the efforts of the “Astrophysics Science Project Integrating Research and Education (ASPIRE: that provides online science lessons designed for 7th-9th grade classrooms. The usage of ASPIRE has grown steadily since its inception in 1997 to nearly 2000 visits (~20000-50000 hits) per day, distributed across north America, and with classroom users in western Europe and Central and South America. I became an honors faculty in 2008 with the course offering “Women in Physics and Their Scientific Contributions” (see ). Currently I am working on the successor to HiRes: the Telescope Array project (TA: concentrating on understanding the composition of the highest energy cosmic rays. But I am also branching into the fascinating study of complex dynamical systems.