Peering into metal with muons

When cosmic rays collide with molecules in the upper atmosphere, they produce particles called muons. About 10,000 of these strike every square metre of the earth’s surface each minute. These particles are able to penetrate several tens of metres through most materials, but are scattered to an unusual extent by atoms that include large numbers of protons in their nuclei. Since this includes uranium and plutonium, muons could have valuable security applications.

Muon tomography is a form of imaging that can be used to pick out fissile materials, even when they are embedded in dense masses. For instance, a tunnel sized scanner could examine entire semi trucks or shipping containers in a short time. Such tunnels would be lined with gas-filled tubes, each containing a thin wire capable of detecting muons on the basis of a characteristic ionization trail. It is estimated that scans would take 20-60 seconds, and less time for vehicles and objects of a known configuration.

Muons have also been used in more peaceful applications: such as looking for undiscovered chambers in the Pyramids of Giza and examining the interior of Mount Asama Yama, in Japan.

Author: Milan

In the spring of 2005, I graduated from the University of British Columbia with a degree in International Relations and a general focus in the area of environmental politics. In the fall of 2005, I began reading for an M.Phil in IR at Wadham College, Oxford. Outside school, I am very interested in photography, writing, and the outdoors. I am writing this blog to keep in touch with friends and family around the world, provide a more personal view of graduate student life in Oxford, and pass on some lessons I've learned here.

4 thoughts on “Peering into metal with muons”

  1. From the first of those:

    “This report describes investigations whether it is possible to use of scattering of cosmic muons for investigation of sealed canisters for spent nuclear fuel. The reason to scan such canisters is to verify the presence of uranium and plutonium inside it in general, and to investigate whether the content agrees with the declared content in particular. Another area of interest could be to check whether the transport vessel for transporting the canisters actually contains a canister or not. Simulations of a conceptual system for scanning of the canisters and the transport vessel are described, as well as the analysis procedures. These simulations have been validated using the same method to simulate the results of a recent test experiment, and the results of a simulation and experiment are in agreement concerning the image resolution. The simulations of a conceptual system for scanning canister demonstrate that is possible to detect if one bundle is missing in the canister. Moreover the simulations of the transport vessel demonstrate that it is possible to verify whether it is empty or not in less than 15 min. This can be accomplished both with attenuation and scattering techniques.”

  2. Muon based x-ray specs let you see through peoples clothing in 20-60 seconds, and less time for people with known configurations!

  3. There was another fantastic technical covert operation, called Project Absorb, underway at the time. By 1983, the CIA had identified the location of every permanent ground based nuclear missile in the Soviet Union, but it wasn’t certain how deadly these missiles were after the Soviets began developing MIRVs (multiple warheads on single launchers). CIA scientists knew that each warhead emitted a tiny amount of radiation, so they designed a souped-up Geiger counter to determine the number of warheads each missile contained. The Geiger counter was mounted on a cargo container that was shipped east along the Trans Siberian railroad from a Pacific port. En route, it passed a Soviet train carrying MIRV missiles, and in the seconds it took for the trains to pass, the Geiger counter counted the warheads.

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