Silicon Strip Cosmic Muon Detectors for Homeland Security

Organization: NNSS Mission Support and Test Services, LLC
Co-Developer(s): Fermi National Accelerator Laboratory Los Alamos National Laboratory
Year: 2018

High energy cosmic particles called muons rain down from the atmosphere. Silicon Strip Cosmic Muon Detectors for Homeland Security can identify where and when a cosmic muon particle contacts a material and communicate that information to a signal processing system. A muon tracker uses planes of muon detectors to identify the path of a muon prior to entering the region to be evaluated and as the muon exits the region. High-energy muons pass relatively unimpeded through most obstacles, including humans, but scatter significantly when they interact with materials having a high atomic number. Each material penetrated changes the muons’ trajectory in a predictable manner. For instance, materials having a high atomic number, such as uranium and plutonium, produce a signature that is different from lead, steel, or concrete. The signature trajectory distribution for the material of interest is programmed into the tracking system so that the system alarms when that particular signature is observed. Using these signatures, muon detectors can be employed in nonintrusive, passive systems watching for a variety of materials. At ports of entry, a system can be used to monitor for concealed items such as gold, weapons, ammunition, or nuclear materials. A detector system could also be used to identify an improvised device being left on the side of a road. The system’s software can be programmed to alarm when a detector communicates the signature for any items of interest. On a larger scale, muon tomography has been used for geologic imaging and the evaluation of archaeological sites. The slim profile of silicon strip muon detectors provides versatility and can be an improvement to any application of muon imaging. Silicon strip detectors can be stealthily employed—they can be embedded into walls, ceilings, and portable devices.

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