Louis Rosen was born in New York City on June 10, 1918. Rosen received his BA and MS degrees from the University of Alabama and his PhD from Pennsylvania State University; later teaching at both universities.
In 1944, Rosen joined the laboratory as a member of the Manhattan Engineering District's Project Y. Rosen's wartime work in neutron cross-section measurements and nuclear test diagnostics proved immensely valuable. After the war, many scientists left the Laboratory to pursue careers in industry or academia, but Rosen stayed behind.
To help ensure that Los Alamos remained a premier science institution, Rosen led the way in developing the world's most powerful linear accelerator. His efforts culminated in the construction of the Los Alamos Meson Physics Facility (LAMPF), which is known today as the Los Alamos Neutron Science Center (LANSCE). From its inception to 1986, Louis Rosen served as director.
During his career, Rosen received many honors. In 1963, he won the E. O. Lawrence Award for his work in developing new experimental techniques that led to a better understanding of the atomic nucleus. His innovations also led to more effective methods for diagnosing the behavior of weapons. His most recent award was the 2002 Los Alamos National Laboratory Medal, the highest award the lab can bestow upon an individual.