A Detector That Can Hear a Single Electron
Light hits a silicon wafer, and a single electron is born inside it. An ordinary instrument wouldn't notice — the signal is too faint. The new detector not only hears it but also determines its energy with an accuracy of 589 millielectronvolts. That's like distinguishing the footsteps of an ant at arm's length.
Inside the detector, a particle knocks an electron out of a silicon atom. This takes 0.