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| In the flying laboratory: a new method makes it possible to analyse radioactive sources more accurately from the air. Photo Credit: © Paul Scherrer Institute PSI/Markus Fischer |
Scientific Frontline: Extended "At a Glance" Summary: Aerial Radioactivity Detection
The Core Concept: A new computational method developed by the Paul Scherrer Institute (PSI) that enables rapid, highly accurate identification, quantification, and localization of radioactive materials from airborne detectors.
Key Distinction/Mechanism: Unlike traditional simulations that take hours or days to calculate how gamma-ray energy spectra (a radioactive material's "fingerprint") are distorted by air scattering and helicopter metallic surfaces, this new mathematical tool uses a highly efficient Bayesian inference algorithm to calibrate the detector and analyze data in seconds.
Major Frameworks/Components:
- Gamma-ray Spectrometry: Measuring the energy spectrum of emitted gamma photons to identify specific radionuclides.
- Spectral Distortion Modeling: Accounting for the scattering of gamma photons by the atmosphere and the structural materials of the measuring aircraft.
- Bayesian Inference: Utilizing a sophisticated statistical algorithm to rapidly process complex, distorted signal data.
Branch of Science: Nuclear Physics, Data Science, Environmental Science
Future Application: Real-time disaster response monitoring following nuclear reactor accidents or terrorist incidents, routine environmental radiological surveys, and geophysics research.
Why It Matters: Time is critical during radioactive emergencies; reducing the analysis time from days to seconds allows authorities to make immediate, life-saving decisions regarding evacuations and the distribution of protective measures like iodine tablets.
How do you measure radioactivity from the air? With a high-tech detector, a Super Puma helicopter, and a clever algorithm.
Extreme situations demand speed: researchers at the Paul Scherrer Institute (PSI) have developed a new computational method that makes it possible to identify radioactive material from the air more accurately within seconds and to determine its quantity and location more precisely. This significantly improves on the usual method of detection from helicopters. The method can also be applied in geophysics or the monitoring of nuclear material.
There are emergencies one hopes will never occur, but for which society and government nevertheless want to be prepared. These include the potential release of radioactivity after a reactor accident or a terrorist attack using radioactive material. For authorities to react rapidly and effectively in such cases—that is, to initiate evacuations and distribute appropriate protective equipment or iodine tablets—the extent of the danger to people and the environment must first be assessed. Among the things that would come into play in a situation like that are flying laboratories—helicopter-borne detectors with which the position, type, and quantity of radioactive material can be determined.
In research for his doctoral thesis, carried out in the Calibration Laboratory of the Radiation Safety and Security Division at the Paul Scherrer Institute, David Breitenmoser developed mathematical tools that significantly improve data analysis in flying laboratories: radioactive material can be identified more accurately and in a matter of seconds. The results of this research have now been published in the journal Nature Communications. The new analysis method is not only relevant for disaster situations but can also be used, for example, in the monitoring of nuclear facilities.
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David Breitenmoser, Alberto Stabilini, and Malgorzata Kasprzak (from left to right) are working to make the rapid identification of radioactive from the air even better.
Photo Credit: © Paul Scherrer Institute PSI/Markus Fischer
The Blurred Fingerprint
“Every radioactive material has a characteristic fingerprint created by the gamma rays it emits during radioactive decay,” Breitenmoser says. This fingerprint consists of the energy spectrum of the gamma rays, which can be measured with a special detector. In principle, the distribution of gamma-ray energies can reveal both the type and quantity of the material.
However, there is a difficulty: the gamma photons emitted by the material—high-energy light particles that make up gamma rays—are scattered on the way, both by the air and by the helicopter carrying the detector. This alters the energy spectrum. In other words, the fingerprint is blurred and therefore no longer directly recognizable.
To find out how a specific radionuclide fingerprint is distorted and to calibrate the detector accordingly, researchers simulate these effects on a computer. However, such calculations are very complex and can take several hours or even days. They therefore would not come into play for time-critical applications such as a reactor accident.
“The simulations are also very slow because, up to now, they have been somewhat inefficient,” Breitenmoser says. For example, of around 10,000 gamma photons emitted by a radioactive source on the ground, only one reaches the helicopter—and even that is scattered by the many metallic surfaces in the helicopter.
Published in journal: Nature Communications
Title: Quantitative mobile gamma-ray spectrometry through Bayesian inference
Authors: David Breitenmoser, Alberto Stabilini, Malgorzata Magdalena Kasprzak, and Sabine Mayer
Source/Credit: Paul Scherrer Institute | Oliver Morsch
Edited by: Scientific Frontline
Reference Number: phy102626_02
