Jie Feng

An X-ray image is like a photograph taken in the dark with a very short flash: anything that moves comes out blurred. Conventional X-ray detectors are large arrays of millions of pixels, and by the time they read out one frame, the next is already missed. For a spinning turbine or a beating heart, such sluggishness is a death sentence. A team of researchers sidestepped this problem by ditching the array altogether.

Laser light is like a perfectly aligned row of soldiers on parade: all waves oscillate in the same plane. Such light is called polarized. In a new study, physicists have for the first time produced polarized gamma rays by colliding electrons with a powerful laser pulse.

A laser hits a target of thin wires, and within tens of femtoseconds (billionths of a billionth of a second) knocks out a stream of protons. These protons fly into a converter made of lithium and deuterium, where neutrons are born.