An imaging spectrometer based on high resolution microscopy of fluorescent aluminum oxide crystal detectors

Fluorescent Nuclear Track Detector (FNTD) technology was tested as an imaging, spectroscopic tool for radionuclide analysis. This investigation intended to distinguish between characteristic alpha-particles of Pu-239 (5.2 MeV), U-234 (4.8 MeV) and U-238 (4.2 MeV). FNTDs are Al2O3:C,Mg single crystals with color centers that undergo radiochromic transformation. FNTD readout is non-destructive and is performed with fluorescence laser scanning confocal microscopy. Ionization events register in the detector as bright fluorescent features on a weak fluorescent background. Images were acquired at several incrementing depths in the detector to produce 3D datasets. Spectroscopic information was obtained by measuring alpha-particle range in the detector after 3D image reconstruction. The resolution of this technique is fundamentally limited by particle range straggling (about 3.8% (k = 1) at these alpha-particle energies). The spectroscopic line-width as full width at half maximum (FWHM) was determined to be 0.4 MeV enabling discrimination between the isotopes of interest. (c) 2013 Elsevier Ltd. All rights reserved.