Nanocrystals could be key to low-cost radiation detectors

A team of industrial and university researchers has shown that nanoparticles smaller than 10 nanometres can be incorporated into scintillation devices capable of detecting and measuring X-rays and gamma rays emitted by nuclear materials.

The proof-of-concept study, described in the Journal of Applied Physics, suggests that nanocrystals – nanoparticles clustered together to mimic the densely-packed crystals traditionally used in scintillation devices – may one day yield radiation detectors that are easy and inexpensive to manufacture, can be produced quickly in large quantities, are less fragile, and capture most of the X-ray and gamma ray energies needed to identify radioactive isotopes.

Earlier studies have shown that when X-rays or gamma rays strike these miniature, non-crystalline scintillators, some atoms within them are raised to a higher energy level.

These atoms de-excite and give off their energy as optical photons in the visible and near-visible regions of the electromagnetic spectrum.

The photons can be converted to electrical pulses, which, in turn, can be measured to quantify the X-ray and gamma radiation detected and help locate its source.

In the latest experiment, the researchers suspended nanoparticles of lanthanum halide and cerium tribromide (loaded in 5 per cent and 25 per cent concentrations) in oleic acid to create nanocomposite scintillators with sizes between 2-5 nanometres.

When compared to computer models and data from prior studies, the nanocomposite detectors matched up well in their ability to discern X-rays and gamma radiation.

When compared to an existing radiation detection system of similar size that uses plastic, the 25 per cent loaded nanocomposite fared better than the 5 per cent loaded, but still was only about half as efficient.

According to a statement the researchers conclude that more work is needed to refine and optimise their nanocrystal system.

An article entitled Lanthanum Halide Nanoparticle Scintillators for Nuclear Radiation Detection is published in the Journal of Applied Physics.

The team was made up of researchers from Remote Sensing Laboratory, Las Vegas; National Security Technologies, New Mexico; Remote Sensing Laboratory, Andrews Air Force Base, Maryland; University of Nevada; Georgia Tech Research Institute; and RMD, Massachusetts.