National Nuclear Security Administration

Gamma Rays: They're small but mighty

October 19, 2018

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How NNSA uses gamma rays to complete its missions
Twin-engine Bell 412 helicopter operated by NNSA in Nevada. AMS teams fly “low and slow” to survey large areas and provide real-
An Aerial Measuring System helicopter

Gamma rays are a penetrating form of radiation that emerges from the radioactive decay of atomic nuclei. It’s the highest range of energy on the spectrum, found in neutron stars, supernova explosions, and near black holes. 

Researchers at Lawrence Livermore National Laboratory have used gamma rays to help law enforcement agencies determine rightful ownership or the origin of rare and valuable items, ranging from dinosaur bones to software. By printing microscopic, invisible amounts of radioisotopes onto an item, its unique digital fingerprint can be read and verified with gamma-ray spectroscopy.

Aerial Measuring System (AMS) aircraft use on-board computers to analyze large amounts of gamma ray radiation data to prepare for, respond to, and mitigate nuclear and radiological accidents and incidents globally. Aircraft are on-call 24/7.

The High Energy Radiation Megavolt Electron Source (Hermes-III) at Sandia National Laboratories
The High Energy Radiation Megavolt Electron Source (Hermes-III) at Sandia National Laboratories

AMS flew for more than 500 hours in response to the Fukushima disaster. Together with the U.S. Forces Japan, and the Government of Japan, radiation levels over 3,000 square miles surrounding the power plant were accurately mapped.

The High Energy Radiation Megavolt Electron Source (Hermes-III) at Sandia National Laboratories is the world’s most powerful gamma ray generator. HERMES-III produces a highly energetic beam that tests the capability of electronics to survive a burst of radiation that approximates the output of a nuclear weapon. The machine can accommodate targets that range in size from a single transistor to large vehicles.

The On-Line Enrichment Monitor (OLEM)
The On-Line Enrichment Monitor (OLEM)

The On-line Enrichment Monitor (OLEM) bolsters nuclear nonproliferation efforts by detecting gamma rays in real-time. Developed by our National Laboratories to verify compliance with nuclear safeguards agreements, OLEM technology has been transferred to the International Atomic Energy Agency.

Uranium-235 atoms emit a particular gamma ray signature that can be detected by OLEM and used to determine enrichment levels. The concentration of uranium-235 atoms passing through a pipe is matched with gas density, which is extrapolated from temperature and pressure. The resulting data helps inspectors instantly know agreements are being honored. Previously available sampling techniques took up to three weeks to yield results.

Research at NNSA spans the entire electromagnetic spectrum – take a look at findings at other frequencies and how they help further the missions of the Nuclear Security Enterprise.