Stanford, SLAC researchers demonstrate 'accelerator on a chip'

The tiny new technology could spawn new generations of smaller, less expensive devices for science and medicine.

The nanostructured glass chip is smaller than a grain of rice. Photo: Brad Plummer

In an advance that could dramatically shrink particle accelerators for science and medicine, researchers used a laser to accelerate electrons at a rate 10 times higher than conventional technology in a nanostructured glass chip smaller than a grain of rice.

The achievement was reported today in the journal Nature by a team including scientists from the U.S. Department of Energy's SLAC National Accelerator Laboratory and Stanford University.

"We still have a number of challenges before this technology becomes practical for real-world use, but eventually it would substantially reduce the size and cost of future high-energy particle colliders for exploring the world of fundamental particles and forces," said Joel England, the SLAC physicist who led the experiments.

"It could also help enable compact accelerators and X-ray devices for security scanning, medical therapy and imaging, and research in biology and materials science."

Because it employs commercial lasers and low-cost, mass-production techniques, the researchers believe it will set the stage for new generations of "tabletop" accelerators.

At its full potential, the new "accelerator on a chip" could match the accelerating power of SLAC's 2-mile-long linear accelerator in just 100 feet, and deliver a million more electron pulses per second.

This initial demonstration achieved an acceleration gradient, or amount of energy gained per length of the accelerator, of 300 million electronvolts per meter. That's roughly 10 times the acceleration provided by the current SLAC linear accelerator.

"Our ultimate goal for this structure is one billion electronvolts per meter, and we're already one-third of the way in our first experiment," said Stanford applied physics Professor Robert Byer, the principal investigator for this research.

Today's accelerators use microwaves to boost the energy of electrons. Researchers have been looking for more economical alternatives, and this new technique, which uses ultrafast lasers to drive the accelerator, is a leading candidate.

Particles are generally accelerated in two stages. 

• First they are boosted to nearly the speed of light. 
• Then any additional acceleration increases their energy, but not their speed; this is the challenging part.

In the accelerator-on-a-chip experiments, electrons are first accelerated to near light-speed in a conventional accelerator. Then they are focused into a tiny, half-micron-high channel within a glass chip just half a millimeter long. The channel had earlier been patterned with precisely spaced nanoscale ridges. Infrared laser light shining on the pattern generates electrical fields that interact with the electrons in the channel to boost their energy. (View animation for more detail.)

Turning the accelerator on a chip into a full-fledged tabletop accelerator will require a more compact way to get the electrons up to speed before they enter the device.

A collaborating research group in Germany, led by Peter Hommelhoff at Friedrich Alexander University and the Max Planck Institute of Quantum Optics, has been looking for such a solution. It simultaneously reports in Physical Review Letters its success in using a laser to accelerate lower-energy electrons.

Applications for these new particle accelerators would go well beyond particle physics research. Byer said laser accelerators could drive compact X-ray free-electron lasers, comparable to SLAC's Linac Coherent Light Source, that are all-purpose tools for a wide range of research.

Another possible application is small, portable X-ray sources to improve medical care for people injured in combat, as well as to provide more affordable medical imaging for hospitals and laboratories. That's one of the goals of the Defense Advanced Research Projects Agency's Advanced X-Ray Integrated Sources program, which partially funded this research. Primary funding for this research is from the U.S. Department of Energy Office of Science.

The study's lead authors were Stanford graduate students Edgar Peralta and Ken Soong. Peralta created the patterned fused silica chips in the Stanford Nanofabrication Facility. Soong implemented the high-precision laser optics for the experiment at SLAC's Next Linear Collider Test Accelerator. Additional contributors included researchers from the University of California-Los Angeles and Tech-X Corp. in Boulder, Colo.

SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. SLAC is operated by Stanford University for the U.S. Department of Energy Office of Science.

Mike Ross is a science writer at the SLAC National Accelerator Laboratory.
Media Contact

• Robert Byer, Applied Physics, Stanford: rlbyer@stanford.edu, (650) 723-0226
• Joel England, SLAC: england@slac.stanford.edu, (650) 926-3706
• Andy Freeberg, SLAC media relations manager: (650) 926-4359, afreeberg@slac.stanford.edu
• Dan Stober, Stanford News Service: (650) 721-6965, dstober@stanford.edu

ORIGINAL: Stanford
By Mike Ross

September 27, 2013

World’s thinnest glass is just two atoms thick

ORIGINAL: EarthSky

Sep 12, 2013


At just a molecule thick, it’s a new record: The world’s thinnest sheet of glass, a serendipitous discovery by scientists at Cornell and Germany’s University of Ulm, is recorded for posterity in the Guinness Book of World Records.

Direct Imaging of a Two-Dimensional Silica Glass on Graphene. Credit: P.Y. Huang, S. Kurasch et al.

The “pane” of glass, so impossibly thin that its individual silicon and oxygen atoms are clearly visible via electron microscopy, was identified in the lab of David A. Muller, professor of applied and engineering physics and director of the Kavli Institute at Cornell for Nanoscale Science.

The work that describes direct imaging of this thin glass was first published in January 2012 in Nano Letters, and the Guinness records officials took note. The record will now be published in the Guinness World Records 2014 Edition.

Just two atoms in thickness, the glass was an accidental discovery, Muller said. The scientists had been making graphene, a two-dimensional sheet of carbon atoms in a chicken wire crystal formation, on copper foils in a quartz furnace. They noticed some “muck” on the graphene, and upon further inspection, found it to be composed of the elements of everyday glass, silicon and oxygen.

They concluded that an air leak had caused the copper to react with the quartz, also made of silicon and oxygen. This produced the glass layer on the would-be pure graphene.

Besides its sheer novelty, Muller said, the work answers an 80-year-old question about the fundamental structure of glass. Scientists, with no way to directly see it, had struggled to understand it: it behaves like a solid, but was thought to look more like a liquid. Now, the Cornell scientists have produced a picture of individual atoms of glass, and they found that it strikingly resembles a diagram drawn in 1932 by W. H. Zachariasen – a longstanding theoretical representation of the arrangement of atoms in glass.

“This is the work that, when I look back at my career, I will be most proud of,” Muller said. “It’s the first time that anyone has been able to see the arrangement of atoms in a glass.”

What’s more, two-dimensional glass could someday find a use in transistors, by providing a defect-free, ultra-thin material that could improve the performance of processors in computers and smartphones.

The work at Cornell was funded by the National Science Foundation through the Cornell Center for Materials Research.

Via Cornell University

Light completely stopped for a record-breaking minute

ORIGINAL: New Scientist

by Jacob Aron

25 July 2013

Not so fast (Image: Dougal Waters/Getty)

The fastest thing in the universe has come to a complete stop for a record-breaking minute. At full pelt, light would travel about 18 million kilometres in that time – that's more than 20 round trips to the moon.

"One minute is extremely, extremely long," says Thomas Krauss at the University of St Andrews, UK. "This is indeed a major milestone."

The feat could allow secure quantum communications to work over long distances.

While light normally travels at just under 300 million metres per second in a vacuum, physicists managed to slow it down to just 17 metres per second in 1999 and then halt it completely two years later, though only for a fraction of a second. Earlier this year, researchers kept it still for 16 seconds using cold atoms.

Stripy light To break the minute barrier, George Heinze and colleagues at the University of Darmstadt, Germany, fired a control laser at an opaque crystal, sending its atoms into a quantum superposition of two states. This made it transparent to a narrow range of frequencies. Heinze's team then halted a second beam that entered the crystal by switching off the first laser and hence the transparency.

The storage time depends on the crystal's superposition. A magnetic field extends it but complicates the control laser configuration. Heinze's team used an algorithm to "breed" combinations of magnet and laser, leading them to one that trapped light for a minute.

They also used the trap to store and then retrieve an image consisting of three stripes. "We showed you can imprint complex information on your light beam," says Heinze.

Tens of seconds of light storage are needed for a device called a quantum repeater, which would stop and then re-emit photons used in secure communications, to preserve their quantum state over long distances.

It should even be possible to achieve longer light storage times with other crystals, says Heinze, as they have pushed their current material close to its physical limit.

Journal reference: Physical Review Letters, doi.org/m86

Glass microbiology

ORIGINAL: http://www.sciencedump.com/content/glass-microbiology

09/27/2012

This body of glass work has been developed since 2004. Made to contemplate the global impact of each disease, the artworks were created as alternative representations of viruses to the artificially coloured imagery we receive through the media. In fact, viruses have no colour as they are smaller than the wavelength of light. By extracting the colour from the imagery and creating jewel like beautiful sculptures in glass, a complex tension has arisen between the artworks’ beauty and what they represent.

source: http://www.lukejerram.com/glass

Viruses

Swineflu

Smallpox

SARS

Ecoli

HIV