Joel Fajans was a pioneering plasma physicist and antimatter researcher whose work advanced our understanding of nonneutral plasmas and laid the groundwork for groundbreaking measurements of antihydrogen.
A professor of physics at the University of California, Berkeley, Fajans was a founding member of the Antihydrogen Laser Physics Apparatus (ALPHA) collaboration at CERN, where his expertise in magnetically trapped nonneutral plasmas proved instrumental. His contributions—including the critical early decision to use an octupole rather than quadrupole magnetic confinement scheme, improved plasma temperature diagnostics, and novel techniques for enhanced plasma reproducibility—were key achievements that enabled the controlled production and trapping of neutral antihydrogen and opened the door to studies of the fundamental symmetries of matter and antimatter. He was especially proud of conceptualizing and designing the ALPHA apparatus that produced pioneering measurements of the force of Earth’s gravity on antihydrogen.
Fajans earned his B.S. and Ph.D. in physics from MIT, supported by a Hertz Fellowship. His doctoral dissertation on the physics of free electron lasers earned both the inaugural American Physical Society Simon Ramo Thesis Prize and the Hertz Foundation Thesis Prize. After a postdoctoral position at UC San Diego working on nonneutral plasmas with John Malmberg, he joined the UC Berkeley Physics Department in 1988, where he built a prolific career training a generation of graduate students and guiding over two dozen undergraduates through transformative summer research projects at CERN.
Beyond research, Fajans was locally celebrated for his challenging but rewarding Physics 111A Instrumentation Laboratory course, his expertise in the classical mechanics of bicycles, and his devotion to cycling thousands of miles each year through the Berkeley hills and the Jura mountains near CERN.
Fajans’s work was recognized with numerous honors, including the NSF Presidential Young Investigator Award, the ONR Young Investigator Award, a Sloan Fellowship, and the John Dawson Prize for Excellence in Plasma Physics Research. He was a Fellow of the American Physical Society. He passed away on November 17, 2024, at the age of 66.
