The hassle of going through airport security and taking off shoes, watches, belts, and other items could be alleviated with a safe form of electro- magnetic radiation called T-rays, or terahertz radiation. Scientists at the U.S. Department of Energy's Argonne National Laboratory, along with collaborators in Turkey and Japan, have created a compact device that could lead to portable, battery-operated sources of T-rays.

Unlike far more energetic X-rays, T-rays do not have sufficient energy to "ionize" an atom by loosening one of its electrons. This ionization causes the cellular damage that can lead to radiation sickness or cancer. Since T-rays are non-ionizing - 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 penetrates common materials, such as leather, fabric, cardboard, and paper.

These qualities make terahertz devices one of the most promising 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 identify a wider range of hazardous or illegal substances. T-rays can also penetrate the human body by almost half a centimeter, showing promise for medical applications such as treating skin and breast cancer.

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