Diamond Under the Hammer: How X-rays See the Unseen express
A powerful laser strikes a diamond like a sledgehammer, with matter itself serving as the anvil. The impact lasts only an instant but generates pressures a million times greater than atmospheric. Physicists have long dreamed of peering into that moment to see how atoms rearrange under the onslaught.
The X-ray beam here is like a camera flash. The trouble is that the brightness of the flash itself can vary from shot to shot. To avoid guesswork, the researchers devised a "built-in ruler": part of the beam passes through a narrow aperture (collimator) or a layer of stationary material. This signal serves as a reference, like a tuning fork for calibrating an instrument.
The method was tested on a diamond compressed by a shock wave to nearly 1 TPa. By comparing X-ray images of the hot, compressed diamond with a cold reference, the scientists accounted for thermal vibrations of the atoms — which weaken the signal. This allowed them to precisely measure how the crystal lattice of carbon changes under extreme conditions.
This isn't just about setting records. Understanding how matter behaves at such pressures is crucial for modeling planetary interiors, creating new materials, and even for thermonuclear fusion — the very process that powers the stars. The X-ray flash now tells us more.
Original abstract
as written by the authors arXiv:2606.23602
Powder x-ray diffraction (PXRD) under laser-driven dynamic compression is a powerful tool to investigate material response to extreme pressure, temperature and strain rates. Robust PXRD platforms have been developed at kJ and MJ laser facilities worldwide including the Powder X-Ray Diffraction Image Plate (PXRDIP) at the Omega Laser Facility at the Laboratory for Laser Energetics (LLE) and the TARget Diffraction In Situ (TARDIS) at the National Ignition Facility (NIF). Here we present further developments of data analysis methods focused towards improving the fidelity of the PXRD intensity determination for these platforms. We illustrate these methods by discussing how they can be implemented in a data analysis package and applied to shock compression data on diamond near 1 TPa. We discuss using the XRD signal from the collimating pinhole or a layer of un-compressed material in the sample package as \textit{ in-situ} references for XRD intensity. We detail how to compare data collected with different x-ray sources and how to account for thermal damping of XRD signal when comparing XRD from a shock-compressed, hot material with the reference material at ambient.
Diamond is not the hardest material under ultra-high pressures. When compressed, its atoms rearrange into another, even denser crystalline form.
In Arthur C. Clarke's novel "Rendezvous with Rama," an alien spacecraft has a hull made of a material that withstands monstrous pressures — perhaps its strength lies in phase transitions similar to those studied in such experiments.