News in Neutrons...

When a free neutron (green) undergoes a process known as beta decay, it produces a proton (red), an antineutrino (gold) and an electron (blue)–as well as a photon (white). An experiment at NIST measured the range of energies that a given photon produced by beta decay can possess, a range known as its energy spectrum.
Credit: Hanacek/NIST

Topics: Atomic Physics, Big Bang, Particle Physics, Quantum Electrodynamics, Standard Model, Theoretical Physics

A physics experiment performed at the National Institute of Standards and Technology (NIST) has enhanced scientists’ understanding of how free neutrons decay into other particles. The work provides the first measurement of the energy spectrum of photons, or particles of light, that are released in the otherwise extensively measured process known as neutron beta decay. The details of this decay process are important because, for example, they help to explain the observed amounts of hydrogen and other light atoms created just after the Big Bang.

Published in Physical Review Letters, the findings confirm physicists’ big-picture understanding of the way particles and forces work together in the universe—an understanding known as the Standard Model. The work has stimulated new theoretical activity in quantum electrodynamics (QED), the modern theory of how matter interacts with light. The team’s approach could also help search for new physics that lies beyond the Standard Model.

NIST: Physicists measured something new in the radioactive decay of neutrons
Chad Boutin