A new method for neutron detection has been discovered at Johns Hopkins University. Physicists, lead by Christopher Lavelle, made use of a phenomenon called noble gas scintillation.
Their detector contains carbon foam coated in a layer of boron carbide, in a chamber filled with xenon gas.
One new innovation – the low density foam base – disperses the boron evenly throughout the chamber. One form of boron, 10B, absorbs neutrons well. In the experiment, a beam of neutrons is aimed at the chamber, and a fraction of these neutrons are absorbed by boron. When 10B absorbs a neutron, a nuclear reaction takes place. This process releases two high energy particles, which pass some energy to the xenon gas. Finally, the xenon scintillates, emitting light, which is measured.
The ability to detect radiation is extremely important, particularly in matters of security. A cheap, easy way to detect neutron emissions from cargo, for instance, is essential for modern counterterrorist operations. The nuclear industry also creates huge demand for neutron detectors.
If commercialised, this technology would be a massive improvement on current methods. The key component of most neutron detectors, 3He, is already scarce; demand has increased rapidly over the last 10 years, making 3He-based detectors increasingly expensive. Alternatives using boron trifluoride are hampered by the toxicity of this gas. Boron carbide, by contrast, is relatively cheap, safe and sensitive to neutrons.
The next stage will focus on making a commercially viable prototype, by boosting the intensity of the detection signal.