Ultracold Neutrons are Magnetically Trapped at NIST

Abstract

Although the neutron was discovered in 1932, its lifetime wasn't measured until 18 years later, when nuclear reactors became available. Obtaining a precise measurement was a tough experimental challenge back then. John Robson was the first to report such a measurement—at the Chalk River reactor in Canada. Fifty years later, improving the precision is still challenging experimenters.