InnoCentive Challenge Name: Radioactive Material Detection Method
Doc. Number: (internal use only)
My Solution:
Detailed Description of the Solution
The Solver's proposed rapid and reliable detection method for radioactive material within a closed space or container is "T-ray Beam System for Radioactive Material Detection".
Terahertz radiation (T-ray) is in the terahertz band of the electromagnetic spectrum, between microwave and near infrared. T-ray photon beam is directional and stable with temporal and spatial energy uniformity. T-ray beam is harmless to animals including human beings.
T-ray sensor/detector can not only see hidden objects but also tell what those objects are made of. Atoms/Molecules reflect and transmit a characteristic combination of T-ray waves. T-ray system will check to see which wavelengths of T-ray have been absorbed and reflected by the object, and pick up the characteristic spectral signatures of atoms/molecules.
T-ray spectroscopy can distinguish atoms/molecules which appear as different colours to the T-ray sensor/detector. Such a T-ray system will be able to identify radioactive plumes from radioactive decay isotopes (Cs-137, Co-60, etc.), and to characterise radioactive materials from a dirty bomb, for example, from a safe distance.
Timing the T-ray pulse's echo gives the range to the object. T-ray pulses enables spectroscopy to identify a substance by the wavelengths of the T-ray that it reflects because a single pulse actually comprises a broad swath of T-ray frequencies. Analysing the shape of the pulse's echo enables the system to calculate which frequencies were absorbed and then look up what substances produce that absorption pattern.
One T-ray system generates terahertz radiation by shining pulses from a powerful infrared laser on to a crystal of gallium arsenide semiconductor. Another T-ray system generates terahertz radiation by zapping semiconductors with femtosecond-long laser pulses or mix together a pair of infrared laser beams. A quantum cascade laser device is under development as a completely solid-state T-ray laser, using 3 layers of quantum wells, each nanometres thick.
T-ray scanners can see a few metres away. It is expected that within the next few years, the machine could do T-ray spectroscopy at 50 metres or more.
T-ray beam systems available today do not meet all of the Seeker's Technical Requirements because they lack the combination of compactness, cheapness and sensitivity. However, T-ray is a rapidly developing field, so miniaturisation is taking place as we speak.
Companies actively developing T-ray systems include Picometrix, TeraView, ThruVision, Spire, and Advanced Energy Systems.
The diagram below describes one example of T-ray imaging system in which the transmitter and the receiver are combined in an integrated housing. This particular example detects the spatial frequencies of an image and reconstructs the picture from them in a computer.
References and Notes
There is no patent art preventing the use of specific material for their commercial application.
Conclusion
The Solver believes that the novel T-ray Beam System for Radioactive Material Detection will eventually meet all of the Seeker's Technical Requirements and Desirable Properties.
