Luis Walter Alvarez (1911–1988) was an American experimental physicist who was awarded the Nobel Prize in Physics in 1968 for his discovery of resonance states in particle physics using the hydrogen bubble chamber. After receiving his PhD from the University of Chicago in 1936, Alvarez went to work for Ernest Lawrence at the Radiation Laboratory at the University of California, Berkeley. He joined MIT Radiation Laboratory in 1940, where he contributed to a number of World War II radar projects and worked as a test pilot, before joining J. Robert Oppenheimer on the Manhattan Project in 1943. He moved back to Berkeley as a full professor after the war, going on to use his knowledge in work on improving particle accelerators. This 1969 photograph shows Alvarez with a magnetic monopole detector at Berkeley.

Photograph credit: Lawrence Berkeley National Laboratory / Department of Energy