When is a brick a gamma ray spectrometer? When researchers from North Carolina State University harness residual gamma radiation signatures from the common building material to detect the presence or removal of Source: North Carolina State UniversitySource: North Carolina State Universitynuclear materials from a given location.

The quartz and other silicate minerals contained in bricks react to gamma rays by trapping electrons in their crystalline matrix. When subjected to optically stimulated luminescence dosimetry, the electrons release light that can be measured on a photomultiplier, enabling researchers to retrospectively determine if a strong radioactive source might have been present.

The method was tested with 4.5 kg of weapons-grade plutonium and optically stimulated luminescence dosimetry techniques for passive imaging. The location and radius of the target were accurately defined by the passive dosimetry approach.

The results demonstrate the ability to retrospectively measure the source energy with an overall energy resolution of approximately 6 keV and indicate potential to track nuclear materials or expedite dose reconstructions in the wake of nuclear accidents.

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