Thorium-229: How to Hear a Nucleus in an Opaque Crystal
A thin film of thorium dioxide, just 10 nanometers thick, is deposited on a steel disk. A laser pulse strikes it, but instead of the expected glow, the detector catches a stream of electrons.
The Nuclear Pendulum That Ticks More Precisely Than Anything on Earth
The world's most accurate pendulum isn't a steel rod: it's a tiny atomic nucleus. The isotope thorium-229 has a special excited state: to nudge the nucleus into it, you need surprisingly little energy — about what an ultraviolet laser delivers.