Raymond Davis Jr

Today is the birthday of Raymond Davis Jr., who was born in Washington, DC, in 1914. He earned a PhD from Yale University in 1942. After working on radiochemistry for Monsanto, Davis joined the research staff at Brookhaven National Lab, where his supervisor told him “to find something interesting to work on.” Davis decided to develop methods for detecting neutrinos, subatomic particles that are extremely hard to observe, via inverse beta decay. That line of research led to the Homestake experiment in South Dakota. The experiment successfully detected neutrinos from the Sun, but strangely it spotted only about a third of the particles that physicists had expected to see. At first scientists thought something was wrong with Davis’s experiment. But subsequent experiments ultimately solved the so-called solar neutrino problem. It turns out neutrinos oscillate between three varieties, or flavors. Davis’s experiment could detect only one flavor. The discovery of neutrino oscillation in the early 2000s proved that neutrinos have mass, a property not predicted by the standard model of particle physics. Davis shared the 2002 Nobel Prize in Physics for his discovery.

Date in History: 14 October 1914