WHAT kind of matter would you expect to find inside a giant planet? A strange transparent metal created by firing an X-ray laser at aluminium might hold some clues.
To create this exotic state of matter, researchers at the facility in Hamburg, Germany, took a thin piece of aluminium foil and blasted it with an X-ray laser that generated about 10 million gigawatts of power per square centimetre. At standard temperature and pressure, solid aluminium is a lattice of ions surrounded by a sea of free electrons. Each photon in the FLASH beam had enough energy to knock an electron away from an ion, while the photon got absorbed in the process.
Normally in a solid metal, another electron will instantly take the place of the missing one. But FLASH is so powerful that it can rip out one electron from every ion in the foil before other electrons can replace them.
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With one electron removed, the remaining electrons around each ion settle into a different configuration, becoming too tightly bound for the laser to remove them. That means the X-ray photons can no longer be easily absorbed, and they fly straight through the material, making the previously opaque aluminium transparent to X-rays (see diagram).
鈥淭he X-ray photons fly straight through, making the previously opaque aluminium transparent鈥�
This state doesn鈥檛 last long, however. Within a fraction of a nanosecond, the energy pumped into the electrons is delivered to the ions, and the ions fly apart violently (Nature Physics, ). 鈥淎s soon as you make it, the stuff blows up,鈥� says Justin Wark of the University of Oxford.
For an instant, though, Wark and his team can create a new state of matter that is as dense as ordinary solid matter but is extremely hot. 鈥淭hat is the sort of matter you would get towards the centre of a giant planet,鈥� says Wark.
The team hopes to study the properties of this hot, dense matter using newer, more powerful lasers such as the . The higher-energy X-rays produced by these lasers could probe the structure of the new material and measure its properties 鈥� perhaps providing some insight into the heart of Jupiter and other giant planets.
