Tag Archives: x-rays

Machine learning is paving the way towards 3D X-rays

Researchers at the U.S. Department of Energy’s (DOE) Argonne National Laboratory have developed a new AI-based framework that can produce X-ray images in 3D.

The Advanced Photon Source (APS) at Argonne National Laboratory, one of the most technologically complex machines in the world, provides ultra-bright, high-energy x-ray beams for researchers across the USA. Image credits Argonne National Laboratory / Flickr.

The team, which includes members from three divisions at Argonne, has developed a method to create 3D visualizations from X-ray data. Their efforts were meant to allow them to better use the Advanced Photon Source (APS) at their lab, but potential applications of this technology range from astronomy to electron microscopy.

Lab tests showed that the new approach, called 3D-CDI-NN, can create 3D visualizations from data hundreds of times faster than existing technology.

More dimensions

“In order to make full use of what the upgraded APS will be capable of, we have to reinvent data analytics. Our current methods are not enough to keep up. Machine learning can make full use and go beyond what is currently possible,” says Mathew Cherukara of the Argonne National Laboratory, corresponding author of the paper.

The “CDI” in the technique’s name stands for coherent diffraction imaging, which is an X-ray technique that involves reflecting ultra-bright X-ray beams off of a certain sample that’s being investigated. These are later picked up by an array of detectors, and processed to produce the final image. The issue with this, says Cherukara, is that these detectors are limited in what information they can pick up from the beams. The “NN” stands for “neural network”.

Since important information can be missed during this step, software is used to fill it back in. Naturally, this is a very computationally- and time-intensive step. The team decided to train an AI that could side-step this entirely, being able to recognize objects straight from the raw data. They trained the AI using simulated X-ray data.

“We used computer simulations to create crystals of different shapes and sizes, and we converted them into images and diffraction patterns for the neural network to learn,” said Henry Chan, the lead author on the paper and a postdoctoral researcher in the Center for Nanoscale Materials (CNM), a DOE Office of Science User Facility at Argonne, who led this part of the work. “The ease of quickly generating many realistic crystals for training is the benefit of simulations.”

After this, the AI was pretty good: it could arrive at close to the right answer in an acceptable span of time. The team further refined it by adding an extra step to the process, to help improve the accuracy of its output. They then tested it on real X-ray readings of gold particles collected at the APS. The final form of the neural network proved it can reconstruct the information not captured by detectors using less data than current approaches.

The next step, according to the team, is to integrate it into the APS’s workflow, so that it can learn from new data as it’s being taken. The APS is scheduled to receive a massive upgrade soon, which will increase the speed at which it can collect X-ray data roughly 500-fold. With this in mind, having an AI such as the one created by the team available to process data in real-time would be invaluable.

X-rays can allow us to see how materials behave on the nanoscale, i.e. on scales 100,000 smaller than the width of a human hair. But the sheer amount of data captured at such resolutions meant that processing remained time-consuming. Technology such as this, the team explains, would allow us to peer at the very, very small much more easily than ever before. Alternatively, it could help us understand the very large, as well, as several types of astronomical bodies emit X-rays towards Earth.

And, while the work at Argonne was carried out using samples of crystal, there’s no reason why the technology can’t be adapted for medical applications, as well.

“In order to make full use of what the upgraded APS will be capable of, we have to reinvent data analytics,” Cherukara said. “Our current methods are not enough to keep up. Machine learning can make full use and go beyond what is currently possible.”

The paper “Rapid 3D nanoscale coherent imaging via physics-aware deep learning” has been published in the journal Applied Physics Reviews.

NASA pinpoints black holes that send out high-energy X-rays for first time ever

For the first time ever, NASA’s Chandra mission has pinpointed large numbers of black holes that send out high-energy X-rays. Although these unique black holes possess the highest pitched “voices” compared to their lower energy counterparts, until now they have remained elusive.

The blue dots in the above picture represent galaxies that contain supermassive black holes emitting high-energy X-rays. Credit: NASA/JPL-Caltech

The blue dots in the above picture represent galaxies that contain supermassive black holes emitting high-energy X-rays. Credit: NASA/JPL-Caltech

Prior to the current findings, NASA’s Chandra mission has been able to determine many of the black holes that contribute to the X-ray background, but not those that release high-energy X-rays.

The discovery of a large number of black holes that release these high-energy X-rays brings scientists closer to understanding the high-energy X-ray background created by the cosmic choir of black holes in space with the highest voices.

“We’ve gone from resolving just two percent of the high-energy X-ray background to 35 percent,” said Fiona Harrison of Caltech and lead author the upcoming new study describing the findings. “We can see the most obscured black holes, hidden in thick gas and dust.”

Understanding the X-ray background is essential to shed light on the growth patterns of supermassive black holes and the galaxies that they lie in. High-energy X-rays in particular reveal what lies around obscured supermassive black holes that are otherwise difficult to observe and can help determine the distribution of gas and dust that feed and hide these phenomena.

The NuSTAR telescope is the first to be capable of capturing high-energy X-rays into clear pictures and will no doubt be integral in building a more comprehensive picture of the X-ray background using data from these hidden high-energy black holes.

“Before NuSTAR, the X-ray background in high-energies was just one blur with no resolved sources,” Harrison said. “To untangle what’s going on, you have to pinpoint and count up the individual sources of the X-rays.”

“We knew this cosmic choir had a strong high-pitched component, but we still don’t know if it comes from a lot of smaller, quiet singers, or a few with loud voices,” said Daniel Stern of NASA’s Jet Propulsion Laboratory and co-author of the study. “Now, thanks to NuSTAR, we’re gaining a better understanding of the black holes and starting to address these questions.”

The findings will be published in an upcoming issue of The Astrophysical Journal. The data can currently be viewed on the pre-print server arXiv.org.

An artist’s conception of the processes by which a star collapses and becomes a black hole, releasing high-energy gamma rays and X-rays, as well as visible light, in the process (credit: NASA)

Armada of instruments witness the brightest cosmic event of the century: the birth of a black hole

An artist’s conception of the processes by which a star collapses and becomes a black hole, releasing high-energy gamma rays and X-rays, as well as visible light, in the process (credit: NASA)

An artist’s conception of the processes by which a star collapses and becomes a black hole, releasing high-energy gamma rays and X-rays, as well as visible light, in the process (credit: NASA)

Astronomers all over the world rejoiced recently after they were treated to a most privileged event. Using the RAPTOR (RAPid Telescopes for Optical Response) system in New Mexico and Hawaii, in conjunction with the most sophisticated observatories in the world, researchers witnessed what may be the most brightest event this century: an extreme flash of light emanated as a massive star “drew its last breath”, giving birth to a black hole.

The event, dubbed GRB 130427A, took place somewhere in the  constellation Leo and generated a huge flash following the collapse of a massive star simultaneously releasing visible light, X-rays and gamma rays in one big gamma-ray burst. The whole burst lasted for around 80 seconds, which might not seem like much, but considering typically most gamma-ray bursts only last a couple fractions of a second to a few seconds, this should give you an idea of how massive the explosion was.

“This was a Rosetta-Stone event that illuminates so many things — literally,” said  astrophysicist Tom Vestrand. “We were very fortunate to have all of the NASA and ground-based instruments seeing it at the same time. We had all the assets in place to collect a very detailed data set. These are data that astrophysicists will be looking at for a long time to come because we have a detailed record of the event as it unfolded.”

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No doubt this was an extremely rare event and astronomers were very lucky to catch it in full sight. What’s even more fortunate, however, is that the flash was caught by an armada of instruments — including gamma-ray and X-ray detectors aboard NASA’s Fermi, NuSTAR and Swift satellites. This means that a slew of data on GRB 130427A is now available, painting maybe the most complete picture yet of such an event, and allowing scientists to learn more about what happens when a black hole is born. For instance, following the intense gamma-ray  a lingering “afterglow” that faded in lock-step with the highest energy gamma-rays was recorded.

“This afterglow is interesting to see,” said paper co-author Przemek Wozniak of Los Alamos’s Intelligence and Space Research Division. “We normally see a flash associated with the beginning of an event, analogous to the bright flash that you would see coinciding with the explosion of a firecracker. This afterglow may be somewhat analogous to the embers that you might be able to see lingering after your firecracker has exploded. It is the link between the optical phenomenon and the gamma-rays that we haven’t seen before, and that’s what makes this display extremely exciting.”