Understanding Radiation Detection

Arktis Radiation Detectors develops novel detectors for ionizing radiation. While sensitive to a wider range of particles, for most applications the detection of highly penetrating radiation is of interest. Such radiation consists essentially of high energy gamma-rays as well as high energy neutrons.

Brief Explanation of Some Relevant Terms:

Radiation Emitting Materials

High energy gamma and neutron radiation is emitted by radioactive materials. Such materials occur in nature (NORM, naturally occuring radioactive material), others are used in industry (TENORM, technically enhanced naturally occuring radioactive material). Highly radioactive materials (radiation sources) are also commonly used in industry, medicine, and research. Radiation can be harmful to humans if the dose exceeds certain levels. For this reason it is of interest to know whether potentially harmful radiological material is being shipped in freight containers.

Radiological Dispersal Devices

Contraptions for the misuse of radiological material for terrorist purposes are called RDDs (radiological dispersal devices), commonly also referred to as "dirty bombs". The construction and deployment of an RDD does not require significant expertise. For this reason, RDDs are considered a major terrorist threat. Such devices are weapons of mass disruption rather than weapons of mass destruction. While the impact on human health and lives would probably not be superior to that of a conventional explosion, the economic consequences of such an attack may threaten the existence of global container trade.

Nuclear Materials and Nuclear Weapons

Nuclear materials - essentially mixtures of Uranium and/or Plutonium - are prerequisits for the production of nuclear weapons. Nuclear materials emit radiation in the form of gamma rays as well as neutrons. These materials are difficult to obtain, and their manufacturing requires infrastructure only few countries can supply. Furthermore, the actual production of nuclear warheads given the nuclear material of sufficient enrichment poses further technical challenges. Despite the improbability of such a scenario, it is of great interest to ensure that the global maritime container network may not be misused for the intercontinental deployment of such arms.

Radiation Portal Monitors

Radiation Portal Monitors (RPMs) are passive radiation detectors set up at sea ports, border crossings and other points of entry of a country. Containers, trucks, and trains are passed through such portals. They measure the radiation emitted by possible radiological material concealed in freight containers. A common problem of todays RPMs is their susceptibility to false positives, brought forth mainly by NORM and TENORM goods as well as medical isotopes.

Active Interrogation Devices

Radiation can be used to actively search containers of concealed threats. X-ray devices are examples for active interrogation systems: A radiation source (in the example an X-ray tube) emits radiation that traverses the volume being analyzed. The radiation exiting the volume is then measured to give clues about the contents of the volume. Given the dimensions of maritime containers, more penetrating radiation than X-rays is desirable, typically gamma-rays and/or neutrons. While gamma-rays are essentially sensitive to the density of the analyzed materials, neutron systems allow further analysis of the elemental composition.