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Previous work has demonstrated that fluorophosphate (FP) glasses doped with trivalent samarium (Sm3+) can be used as a dosimetric detector in microbeam radiation therapy (MRT) to measure high radiation doses and large dose variations with a resolution in the micrometer range. The present work addresses the use of intense optical radiation at 405nm to erase the recorded dose information in Sm3+-doped FP glass plates and examines the underlying physics. We have evaluated both the conversion and optical erasure of Sm3+-doped FP glasses using synchrotron-generated high-dose x-rays at the Canadian Light Source. The Sm-ion valency conversion is accompanied by the appearance of x-ray induced optical absorbance due to the trapping of holes and electrons into phosphorus-oxygen hole (POHC) and electron (POEC) capture centers. Nearly complete Sm2+ to Sm3+ reconversion (erasure) may be achieved by intense optical illumination. Combined analysis of absorbance and electron spin resonance measurements indicates that the optical illumination causes partial disappearance of the POHC and the appearance of new POEC. The suggested model for the observed phenomena is based on the release of electrons during the Sm2+ to Sm3+ reconversion process, the capture of these electrons by POHC (and hence their disappearance), or by PO groups, with the appearance of new and/or additional POEC. Optical erasure may be used as a practical means to erase the recorded data and permits the reuse of these Sm-doped FP glasses in monitoring dose in MRT. [ABSTRACT FROM AUTHOR]

We report the photoluminescence and x-ray luminescence of lanthanum-stabilized cubic barium chloride with europium (Eu2+) doping, of general composition Ba1-x-yEuyLaxCl2+x. X-ray diffraction patterns confirm that the material adopts a cubic fluorite structure for x=0.125 and 0

Abstract: In this paper we discuss two novel methods of measuring afterglow in scintillators. One method is designed for X-ray detection and the other for neutron detection applications. In the first method a commercial fan-beam scanner of basic design similar to those seen at airports is used to deliver a typically 12ms long X-ray pulse to a scintillator by passing the test equipment through the scanner on the conveyor belt. In the second method the thermal neutron beam from a research reactor is incident on the scintillator. The beam is cut-off in about 1ms using a 10B impregnated aluminum pneumatic shutter, and the afterglow is recorded on a dual range storage oscilloscope to capture both the steady state intensity and the weak decay. We describe these measurement methods and the results obtained for a range of developmental ceramic and glass scintillators, as well as some standard scintillators such as NaI(Tl), LiI(Eu) and the plastic scintillator NE102A. Preliminary modeling of the afterglow is presented. [Copyright &y& Elsevier]

Abstract: We report the results of optical, photo-luminescence and spatial resolution measurements on glass-ceramic and epoxy-composite X-ray storage phosphors. We find that the optical extinction coefficient at the stimulation and emission wavelengths is dominated by scattering for all the samples studied. However, the extinction coefficient is at least an order of magnitude lower in glass-ceramics when compared with the composites. Significantly reduced scattering is found in a composite due to the better match between the refractive indices of the epoxy and crystallite. We show that the spatial resolution using a confocal microscope readout in a glass-ceramic is below and hence this glass-ceramic has potential applications in high resolution radiation imaging. [Copyright &y& Elsevier]

The nanoporous surfaces that can be produced by ion implantation of helium into metals have considerable potential for applications. The structures are characterised by random nanoscale cavities of uniform size, a high degree of swelling and very thin metal "walls" separating the neighbouring cavities. These structures are "seeded" by an earlier stage - a gas-bubble superlattice -- comprising small helium bubbles again of uniform size (∼ 2 nm diameter) ordered on a space lattice having the same symmetry as the host. For the fcc metals the bubble superlattice always contains structural variants -- that is, regions where the ordered bubble array has an orientation that is rational with, but different from, that of the crystal lattice of the host metal. In contrast for bcc metals previous work has suggested that the bubble lattice aligns solely parallel with the host crystal. Here we report the first clear demonstration of the presence of structural variant bubble lattices in a bcc metal. A combination of techniques including helium depth-profiling using HERDA is enabling the helium dose requirements for producing ordered bubble structures to be investigated more closely. These techniques are reviewed. [ABSTRACT FROM AUTHOR]