The location here is the Los Alamos National Laboratory where Louis Slotin was irradiated (the reactor no longer exists).
Louis Alexander Slotin (1 December 1910 – 30 May 1946) was a Canadian physicist and chemist who took part in the Manhattan Project, the secret U.S. program during World War II that developed the atomic bomb. As part of the project, Slotin performed experiments with uranium and plutonium cores to determine their critical mass values. During World War II, Slotin continued his research at Los Alamos National Laboratory.