New experiments aim to pin down subatomic particle’s decay rate
WASHINGTON — Lone neutrons quickly decay, but scientists don’t agree on how long the particles stick around before their demise. New experiments could resolve the dispute — or deepen the mystery.
Outside of a nucleus, neutrons survive only about 15 minutes on average. They quickly decay into a proton, an electron and an antineutrino. Two methods used for measuring the neutron lifetime disagree, leaving scientists uncertain about the subatomic particle’s true longevity (SN: 5/19/12, p. 20).
One technique involves containing chilled neutrons in a trap, or “bottle,” waiting awhile, and counting the remaining neutrons to determine how many decayed. Other experiments monitor beams of neutrons and count the number of decays by detecting the protons emitted. Bottle measurements come up with lifetimes about 9 seconds