Bob Ellsworth, Zoa Conner, Betty Alexander, Me-Li Chen, Jordan Goodman.Bob Ellsworth, a UMD Physics visiting professor and professor emeritus at George Mason University, died on August 6, 2026 at the age of 89. He earned his Ph.D. from the University of Rochester and pursued a distinguished career in experimental particle and cosmic-ray physics. Working with Professor Gaurang Yodh, Bob helped establish UMD’s cosmic-ray research group. His pioneering measurements using cosmic rays provided the first experimental evidence that the proton-proton cross section increases with energy, a fundamental result in high-energy particle physics. His later research included contributions to the Super-Kamiokande neutrino experiment in Japan, the Cygnus and Milagro observatories in New Mexico, and the HAWC Observatory in Mexico. Professor Jordan Goodman first met Bob as a UMD freshman and recalls, “Bob was a tremendous mentor to me. He taught me the importance of careful experimental work: Always start by looking at the signal.”
Claude Kacser, a faculty member from 1964 to 1997, died on Aug. 24, 2026 at the age of 92. Kacser received his doctorate at Oxford University and accepted postions at Princeton and Columbia universities before joining UMD. He was the author of the 1967 textbook, Introduction to the Special Theory of Relativity. 
Claude KacserKacser was sent to America from Europe as a six-year old in 1940 to escape the Nazi threat. He told his story as part of the "One Thousand Children" project in 2012: Claude Kacser's One Thousand Children Story (American Kindertransport).