The "Los Alamos lifer" died at age 91 at his home in New Mexico.
He was one of the last surviving links to the scientific giants who had created the atomic age — men like J. Robert Oppenheimer and Enrico Fermi as well as Dr. Teller. But more than that, he had also advanced the era.
Dr. Rosen was a lifer at Los Alamos. Where other scientists drifted away, he spent his career there, and built the most intense atom smasher in the world. He was also part ambassador, part lobbyist for the Los Alamos National Laboratory, promoting its continuing importance as a center not only of weapons development but also of basic research.
His atom smasher was his most spectacular project. "This monstrous gadget will give us new windows on the nucleus, a new set of probes," he said in an interview with The New York Times.