Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Jefferson Lab experiment generates THz radiation 20,000 times brighter than anyone else

28.01.2003


An experiment conducted by the Department of Energy’s Jefferson Lab generates THz radiation 20,000 times brighter than anyone else; breakthrough lights way for application development

Experiment generates THz radiation 20,000 times brighter than anyone else; breakthrough lights way for application development

An experiment conducted with Jefferson Lab’s Free-Electron Laser has shown how to make a highly useful form of light -- called terahertz radiation -- 20,000 times brighter than ever before. Jefferson Lab is a Department of Energy laboratory located in Newport News, Virginia.



The name "terahertz radiation" derives from the frequency of the radiation -- of the order of one trillion oscillations per second. The corresponding wavelength is of the order of tenths of a millimeter. Terahertz radiation is thus located in the spectrum of electromagnetic radiation between the upper end of the microwave range (mm wavelength) and the far infrared (hundredths of mm).

Terahertz radiation is non-ionizing and shares with microwaves the capability to penetrate a wide variety of non-conducting materials.

Gwyn Williams, JLab’s Free-Electron Laser Basic Research Program manager, conceived and led the multi-laboratory team conducting the experiment, which took place during November 2001. The results were published in the Nov. 14, 2002, issue of the international science journal Nature.

Among the prospective benefits, the breakthrough lights the way toward better detection of concealed weapons, hidden explosives and land mines; improved medical imaging and more productive study of cell dynamics and genes; real-time "fingerprinting" of chemical and biological terror materials in envelopes, packages or air; better characterization of semiconductors; and widening the frequency bands available for wireless communication.

To produce for the first time ever, intense terahertz radiation, researchers from JLab and two other Department of Energy laboratories -- Brookhaven National Lab and Lawrence Berkeley National Lab -- made use of the fact that the driver linac of JLab’s Free-Electron Laser is made up of intense electron bunches that are a few tenths of a millimeter long, i.e. comparable to the wavelength of terahertz radiation. Sending any energetic electron beam through a magnetic field makes the beam emit radiation, so-called synchrotron radiation, a process that is greatly enhanced (coherent synchrotron radiation) when the length of the electron bunches is as short or shorter than the radiation wavelength of interest.

Researchers paving way for T-ray applications

For over a decade, scientists worldwide have been pressing the study of light in the terahertz region and looking for better ways to generate and use it. The light is also referred to occasionally as T-rays, T-light or T-lux. An August 16 Science magazine article, "Revealing the Invisible," reported that "much research is being directed toward the development of T-ray sources and detectors, particularly for applications in medical imaging and security scanning systems." Xi-Cheng Zhang, a T-ray expert at Rensselaer Polytechnic Institute, predicts that terahertz light will be "the future ’killer application’ ... in biomedicine."

Picometrix Tochigi Nikon Corporation and Teraview -- a Cambridge, England, start-up associated with Toshiba -- have begun commercializing low-power terahertz systems. A few hospitals are already testing comparatively dim sources of terahertz light for detecting skin cancer.

Overall, though, terahertz light still constitutes a gap in the science of light and energy. It inhabits a region of the electromagnetic spectrum not that well understood. Now that a way to generate it at high power has been demonstrated, terahertz light can potentially extend and add widely to the wave-based technologies that have defined the last 150 years: from the telegraph, radio and X-rays to computers, and cell phones.

Up to this point, no other method of generating terahertz waves had yielded more than two-thousandths of a watt in power. But Williams and his colleagues extracted nearly 20 watts -- some 20,000 times more. "Think of a candle and then think of a floodlight," says Williams.

But no matter how bright they are, terahertz light rays can’t penetrate metal or water. So they can’t be used to inspect cargo containers on arriving ships or to diagnose conditions deep inside the human body."Nevertheless," says Williams, "the growing awareness of terahertz light’s usefulness is like what happened a century ago with X-rays -- only terahertz light will have a much wider range of applications. The task now will be to develop those uses."

Bringing 10-year-old idea to fruition

About 10 years ago Williams wrote a paper proposing a method for generating large amounts of terahertz light. In the mid-90s he started following the development of JLab’s Free-Electron Laser. Williams came to Jefferson Lab from Brookhaven National Lab in the spring of 2000; he actively began pursuing his experiment last June, when he drove a van to Brookhaven to bring back a spectrometer on loan from his old laboratory. Kevin Jordan and George Neil, both JLab staff, soon had it installed and proof-of-principle experiments took place. The final run, with a better spectrometer and detector, took place in early November 2001 and included Larry Carr from Brookhaven, and Michael Martin and Wayne McKinney from Lawrence Berkeley National Lab.

"We didn’t create something new," Williams explains. "The terahertz light had always been there inside of the FEL’s vacuum-sealed beam pipe. We just figured out how to open the pipe, put in a window to let the light out, and how to measure it. Williams is looking forward to performing proof-of-principle experiments of the capabilities of THz light with the upgraded FEL and a newly designed section of FEL beam pipe that should allow even more of the light out.

Williams and his collaborators presented their results at the First International Conference on terahertz Radiation in December of 2001, and shortly thereafter he wrote the experiment up and submitted it to Nature. Due to the novel arena, it took some time before the paper was accepted, but it finally was.

While the U.S. Navy funded the FEL’s construction to investigate the science and technology of high-power laser beams whose precise wavelength can be selected, the funding to run Williams’ and his colleagues’ experiment was from the Commonwealth of Virginia.

Linda Ware | EurekAlert!

More articles from Power and Electrical Engineering:

nachricht High-speed surveillance in solar cells catches recombination red-handed
14.02.2019 | Osaka University

nachricht Sodium is the new lithium: Researchers find a way to boost sodium-ion battery performance
04.02.2019 | Nagoya Institute of Technology

All articles from Power and Electrical Engineering >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Regensburg physicists watch electron transfer in a single molecule

For the first time, an international team of scientists based in Regensburg, Germany, has recorded the orbitals of single molecules in different charge states in a novel type of microscopy. The research findings are published under the title “Mapping orbital changes upon electron transfer with tunneling microscopy on insulators” in the prestigious journal “Nature”.

The building blocks of matter surrounding us are atoms and molecules. The properties of that matter, however, are often not set by these building blocks...

Im Focus: University of Konstanz gains new insights into the recent development of the human immune system

Scientists at the University of Konstanz identify fierce competition between the human immune system and bacterial pathogens

Cell biologists from the University of Konstanz shed light on a recent evolutionary process in the human immune system and publish their findings in the...

Im Focus: Transformation through Light

Laser physicists have taken snapshots of carbon molecules C₆₀ showing how they transform in intense infrared light

When carbon molecules C₆₀ are exposed to an intense infrared light, they change their ball-like structure to a more elongated version. This has now been...

Im Focus: Famous “sandpile model” shown to move like a traveling sand dune

Researchers at IST Austria find new property of important physical model. Results published in PNAS

The so-called Abelian sandpile model has been studied by scientists for more than 30 years to better understand a physical phenomenon called self-organized...

Im Focus: Cryo-force spectroscopy reveals the mechanical properties of DNA components

Physicists from the University of Basel have developed a new method to examine the elasticity and binding properties of DNA molecules on a surface at extremely low temperatures. With a combination of cryo-force spectroscopy and computer simulations, they were able to show that DNA molecules behave like a chain of small coil springs. The researchers reported their findings in Nature Communications.

DNA is not only a popular research topic because it contains the blueprint for life – it can also be used to produce tiny components for technical applications.

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Global Legal Hackathon at HAW Hamburg

11.02.2019 | Event News

The world of quantum chemistry meets in Heidelberg

30.01.2019 | Event News

Our digital society in 2040

16.01.2019 | Event News

 
Latest News

Gravitational waves will settle cosmic conundrum

15.02.2019 | Physics and Astronomy

Spintronics by 'straintronics'

15.02.2019 | Physics and Astronomy

Platinum nanoparticles for selective treatment of liver cancer cells

15.02.2019 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>