John Zinn

John Zinn (lovingly called "Geezer") was born February 28, 1928, in Brooklyn, NY and died at his beloved El Castillo Life Plan Community in Santa Fe on February 17, 2025, 11 days before turning 97. He was happy and active until the end, dancing at a Valentine's Day party three days prior to his death. He passed away peacefully several hours after falling in his room.

John grew up in Manhasset, NY and graduated from Cornell University in 1949. While serving in the Army during the Korean War, he was among those observing Operation Desert Rock in Nevada in 1951, the first nuclear bomb test involving US military troops. John married Renate Meerkamp in 1954, welcomed son Kai a year later, received his PhD in Physical Chemistry from the University of California at Berkeley, and went to work at Los Alamos National Laboratory in 1957. Sons Lennard and Jeff were born in 1958 and 1961 in Los Alamos, where he and Renate resided until moving to Santa Fe in 2012.

John developed the original version of the RADFLO code, a standard tool today for examining coupled radiation and hydrodynamics in fireballs and monitoring international adherence to nuclear test ban treaties. His extensive investigation of the physics and chemistry of nuclear explosions forms the basis of modern understanding of this complex phenomenology. His work included extended stints in Maui, Norway, Boulder, Puerto Rico, Brazil, and Germany. He continued to work at Los Alamos and Sandia Labs until age 85.

John lived an active life, pursuing skiing, tennis, hiking, whitewater rafting, and world travel with his family. He and Renate were active in hiking groups and skiing at Pajarito Mountain into their 80s. Their travels took them all over the world, including observing total eclipses in farflung places.

John is survived by sons Kai of Altadena, CA, Lennard of Boulder, CO, and four grandchildren: Emily, of Boulder, CO, Leif, of Claremont, CA, Sarah, of Thornton, CO, and Katya, of Allston, MA.

His memorial service will be April 12 at 10AM at El Castillo, 250 E. Alameda, Santa Fe. In lieu of flowers, please donate to Habitat for Humanity or The Union of Concerned Scientists.