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.
Orbiting Clocks Hunt for Invisible Fields
In August 2017, gravitational wave detectors caught a signal from the merger of two neutron stars — the ultra-dense remnants of exploded stars. At that very moment, life on Earth was business as usual: planes were landing, cars were driving, and navigators were plotting routes.
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.
Crystalline Acoustics of a Nuclear Whisper
Thorium-229 harbors a secret: its nucleus possesses the lowest excited state among all known nuclides — 8.35 eV.