By Will Soutter
Researchers at Sandia National Laboratories have created a new technique called spectral shape discrimination (SSD) that employs a nanoporous material called metal organic framework (MOF) for radiation detection.
The technique is based on the researcher’s discovery involving MOFs where it was found that doping an MOF causes emission of blue and red light on interaction of the MOF with high-energy particles from nuclear radiation. This method allows for a more effective and economical detection of neutrons as current techniques are hindered by high cost and inability to completely differentiate between neutrons and background gamma rays.
The research is important from nuclear security perspective. Though the initial research on MOF was funded by Sandia's Laboratory Directed Research and Development (LDRD), the remaining work has been backed by funds from the National Nuclear Security Administration's (NNSA) Defense Nuclear Nonproliferation research office. The new technology employs plastic scintillators which fluoresce on collision with high-energy particles. MOFs are porous in nature. This facilitates the addition of dopants to enhance the inherent scintillation properties.
The research team employed the heavy metal compound of iridium added in organic light-emitting diodes (OLEDs) as dopant to MOFs in order to increase the light output. The team discovered that the dopants not only increased the brightness of the emitted light by scavenging the high-energy electrons that were not converted to light but also resulted in emission of light of different color. SSD thus overcomes the challenges of current radiation detection methods in distinguishing neutrons from other particles by aiding detection on the basis of emitted light color.