Keywords: dysprosium, holmium, neutron capture, potassium bromide, mid–infrared, nanocrystals, neutron detection, nuclear forensics, nanotechnology, thermal neutrons, optical properties, colloidal synthesis, nanocomposites
Characterisation of potassium bromide loaded with dysprosium fluoride nanocrystals for neutron detection
We explore a novel concept of passive optically–enabled detection of thermal neutrons that exploits transmutation of 164Dy into 165Ho. The concept relies on significant differences in optical properties of Dy and Ho and on our ability to find the most sensitive optical method of differentiating between Dy and Ho. While the concept applies equally well to bulk materials and to nanocrystals (NCs), the nanocrystalline approach is much more attractive due to its significantly lower cost, relative ease of colloidal synthesis of high quality NCs with controlled composition, and superior optical and mechanical properties of NCs compared to their bulk counterparts. One particular advantage of NCs for neutron detection is that in principle they can be integrated into a transparent host without causing optical scattering. Since Ho is known to have strong emission lines in mid–infrared, we considered potassium bromide (KBr), transparent in mid–IR spectral range, to be a suitable host for Dy–containing NCs. Here, we report on synthesis and characterisation of DyF3:10%Ce, HoF3:10%Ce, and DyF3:10%Ho,10%Ce NCs, their insertion into KBr matrix, and optical characterisation of the obtained nanocomposites, both non–irradiated and subjected to neutron irradiation.