An international research team from the Heinz Maier-Leibnitz Research Neutron Source (FRM II) of the Technical University of Munich (TUM) has developed new imaging technology. In the future, this technology could not only improve the resolution of neutron measurements by several times, but could also reduce radiation exposure during x-ray imaging.
Modern cameras are still based on the same principle as 200 years ago: instead of a piece of film, today an image sensor is exposed for a certain period of time in order to record an image. However, the process also records the noise from the sensor. This constitutes a considerable source of interference especially with longer exposure times.
Together with colleagues from Switzerland, France, the Netherlands and the United States, Dr Adrian Losko and his colleagues at TUM at Heinz Maier-Leibnitz Zentrum (MLZ) have now developed a new imaging method that measures individual photons on a time resolved and spatially resolved basis. This separates the photons from the noise, greatly reducing interference.
“Our new detector allows us to capture each individual photon and thus overcome many of the physical limitations of traditional cameras,” explains Losko, instrument scientist at the NECTAR neutron radiography facility at the Heinz Maier-Leibnitz Zentrum at the Technical University. from Munich.
Measure individual photons
Neutron radiography researchers typically use scintillators in their measurements to detect neutrons (such as when examining fossilized dinosaur eggs). When the scintillator material absorbs a neutron, photons are generated which can then be measured.
Until now, all of these cameras captured light during the entire exposure time, which resulted in a lack of definition, depending on the thickness of the scintillator. The new concept of the research team detects each individual photon generated by a neutron.
“The prerequisite was new chip technology as well as hardware and software supporting computational speeds allowing for real-time analysis. This allows us to compose a neutron image by neutron, ”explains Losko. Neutron research here offers an ideal field of testing and application.
Instead of longer exposure times: measure exactly what is happening
Since the absorption of a neutron into the detector generates multiple photons, the new system can use the coincidence measurement of multiple photons to determine individual neutrons. “It takes us away from the traditional model of exposure time and we only measure events that have occurred.”
Compared to all the technologies previously available on the market, the new concept is a considerable improvement since it allows three times the spatial resolution and reduces the amount of noise by more than seven times. “This greatly reduces the limitations resulting from the thickness of the scintillator, which means higher efficiency for high resolution measurements,” explains Losko. And the afterglow of the scintillator, which creates what are called ghost images, is also eliminated.
“Many research neutron source reactor instruments can benefit from our new concept,” observes Losko, citing the FaNGaS (Fast Neutron-induced Gamma-ray Spectrometry) instrument as an example: “since we know exactly when a neutron is arriving, the length of time we measure the gamma particle can be reduced to a millionth of a second. “That would reduce the background noise by a factor of a million, he adds.
Less radioactive exposure and more details in x-rays
The new detector can also be applied in medical fields. When making an X-ray image of a fractured bone for example, fine structures such as capillary fractures would be more easily detectable; at the same time, the patient’s exposure to radiation would be minimized.
“Our method will definitely change detectors in the scientific world,” says Losko. And maybe similar principles will be applied in everyday cameras for personal use as well. Images taken in the dark would be greatly improved, and photographers could adjust exposure time and resolution after exposure is complete. Noise could be virtually eliminated from cameras.
– This press release was originally published on the website of the Technical University of Munich