Secret of a Lifetime
How long a neutron lives holds clues to the cosmos
In the nuclear family, the neutron is clearly the black sheep.
Unlike its sibling the proton, the neutron is eccentrically — and irritatingly — neutral. Because they have no electrical charge, neutrons are hard to guide and focus using electric fields. And unlike protons, which can be liberated by igniting hydrogen gas, the neutron is stubbornly sequestered within the atomic nucleus, making it especially hard to interact with one-on-one.
What’s most annoying is that neutrons are steadfastly secretive. Unlike charged particles, neutrons are hard to detect — making it hard to measure how long they live. Pinning down the length of the neutron’s life span could help physicists better understand many atomic and cosmic processes, from the nature of forces acting on subatomic particles to the distribution of matter in the moments following the Big Bang. More than 60 years of research has gone into determining the neutron’s average lifetime precisely.