A material was developed for nuclear radiation detection that could provide a significantly less expensive alternative to the detectors now in commercial use. Specifically, the high-performance material is used in a device that can detect gamma rays — weak signals given off by nuclear materials — and easily identify individual radioactive isotopes. The device could be used in applications in homeland security such as detecting dirty bombs and the proliferation of nuclear materials.
In 2013, Argonne National Laboratory reported on the promise of cesium lead bromide in the form of perovskite crystals for high-energy radiation detection. Since then, researchers at Argonne and Northwestern have worked to purify and improve the material, which was used to reconfigure the semiconductor device. Instead of using the same electrode on either side of the crystal, two different electrodes were used. With this asymmetrical design, the device only conducts electricity when gamma rays are present.
The performance of the new cesium lead bromide detector was compared to the conventional cadmium zinc telluride (CZT) detector. The new detector performed just as well in detecting gamma rays with high resolution from cobalt-57. It is important to know what the gamma-ray emitting material is because some materials are legal and some are illegal. Each radioactive isotope possesses its own “fingerprint” — a different decay behavior and a unique characteristic gamma-ray emission spectrum. The new cesium lead bromide detector can detect these fingerprints.
The researchers found the detector successfully identified radioactive isotopes americium-241, cobalt-57, cesium-137, and sodium-22. They also produced larger crystal samples to demonstrate the material can be scaled up.