New T-ray source would improve airport security, cancer detection

Going through airport security is a hassle. Shoes, laptops, toothpastes, watches, and belts, liquids, and what not all get taken off, taken out, scanned, examined, handled, and repacked. The end of this hassle just may be in sight: T-rays, a completely safe form of electromagnetic radiation, may reshape not only airport screening procedures but also medical imaging practices. Photonics Online reports that scientists at the U.S. Department of Energy’s Argonne National Laboratory, together with collaborators in Turkey and Japan, have created a compact device which could lead to portable, battery-operated sources of T-rays, or terahertz radiation. By doing so, the researchers, led by Ulrich Welp of Argonne’s Materials Science Division, have successfully bridged the “terahertz gap,” that is, the range of frequencies between microwaves (on the lower side) and infrared (on the higher side) of the electromagnetic spectrum. Scientists and engineers have produced microwave radiation using conventional electric circuits for more than fifty years, Welp said, but terahertz radiation could not be generated that way because of the physical limitations of the semiconducting circuit components. “Right around 1 terahertz, you have a range of frequencies where there have never been any good solid-state sources,” he added. “You can make those frequencies if you are willing to put together a whole table full of expensive equipment, but now we’ve been able to make a simple, compact solid-state source.”

Unlike far more energetic X-rays, T-rays do not have sufficient energy to “ionize” an atom by knocking loose one of its electrons. This is good news, because this ionization causes the cellular damage that can lead to radiation sickness or cancer. Since T-rays are non-ionizing radiation, like radio waves or visible light, people exposed to terahertz radiation will suffer no ill effects. Furthermore, although terahertz radiation does not penetrate through metals and water, it does penetrate through many common materials such as leather, fabric, cardboard, and paper. These qualities make terahertz devices one of the most promising new technologies for airport and national security. Unlike today’s metal or X-ray detectors, which can identify only a few obviously dangerous materials, checkpoints that look instead at T-ray absorption patterns could not only detect but also identify a much wider variety of hazardous or illegal substances.T-rays can also penetrate the human body by almost half a centimeter, and they have already begun to allow doctors better to detect and treat certain types of cancers,