Cesium Lead Bromide Detectors Offer Precise Radioactive Isotope Identification

Security officials are tasked with preventing criminals from smuggling dangerous materials into a country; detecting nuclear substances has been difficult and costly. Researchers have developed new devices based on a low-cost material to aid in the detection and identification of radioactive isotopes.

Using cesium lead bromide in the form of perovskite crystals, the team created highly efficient detectors in both small, portable devices for field researchers and very large detectors.

In addition to being less costly than typical devices, the new method for detecting gamma rays is also highly capable at differentiating between rays of different energies. This method allows users to identify legal versus illegal gamma rays. Detectors like these are critical for national security, where they're used to detect illegal nuclear materials smuggled across borders and aid in nuclear forensics as well as in medical diagnostics imaging.

Using the perovskite material, the team achieved high resolution in energy detection for gamma rays using a pixelated detector design. In past research, the team compared performance of the new cesium lead bromide detector to the conventional cadmium zinc telluride (CZT) detector and found it performed as well in detecting gamma rays. New research that improved crystal sizes and leveraged pixels rather than planar electrodes has advanced the spectral resolution well beyond that of conventional designs, from around 3.8% to 1.4%, detecting energy even from very weak sources.

Radioactive isotopes emit gamma rays that differ slightly in energy, often differing by just a few percentage points. Using the new material, users can better identify the source of gamma rays by pinpointing differences down to a few percentage points. In addition, using even slightly impure materials typically makes detectors less efficient or nonfunctional and producers of devices must seek ultrapure CZT to produce effective readings. The researchers’ material could have five to ten times more impurities than CZT and still perform, making it easier and cheaper to produce. Resolution is also critical to medical imaging like SPECT scans.