DSpace Collection: Nuclear Engineering and Radiological Sciences, Department of (NERS)

Dead Time, Pileup, and Accurate Gamma-Ray Spectrometry

Sat, 29 Oct 1994 22:58:59 GMT

Title: Dead Time, Pileup, and Accurate Gamma-Ray Spectrometry

Authors: Lindstrom, Richard M.; Fleming, Ronald F.

Deposition of ultrathin rare-earth doped Y2O3 phosphor films on alumina nanoparticles

Mon, 13 Mar 2006 22:58:59 GMT

Title: Deposition of ultrathin rare-earth doped Y2O3 phosphor films on alumina nanoparticles

Authors: Lian, Jie; Yang, L; Chen, X Y; Liu, G. K.; Wang, L. M.; Ewing, Rodney C,; Shi, Donglu

Abstract: Ultrathin films of Eu3+ doped Y2O3 were deposited onto alumina nanoparticles using a unique solution synthesis method. The surface structure, composition, and morphology of the thin films deposited were analysed using high resolution transmission electron microscopy (TEM) and high angle annular dark field scanning TEM imaging and energy dispersive x-ray measurements. The films deposited were extremely thin, on the order of 3–5 nm, and uniformly covered all the alumina nanoparticles. X-ray diffraction was used to investigate the phases and structures of the thin films deposited. At the heat treatment temperature of 600 °C, cubic Y2O3 nanocrystals were found in the film while as-coated layers exhibited mainly amorphous features. As the heat treatment temperature increased to 750 °C, the amorphous thin film became well crystallized. Optical properties of Eu3+ doped Y2O3 films were characterized by fluorescence spectroscopy. Strong photoluminescence was observed in the sample annealed at 750 °C, from the fluorescence of Eu3+ ions in a well-crystallized film, consistent with the x-ray diffraction and TEM observations.

Characterization of a laser-ablation-assisted-plasma-discharge-metallic ion source

Tue, 31 Oct 1995 22:58:59 GMT

Title: Characterization of a laser-ablation-assisted-plasma-discharge-metallic ion source

Authors: Lash, J S; Gilgenbach, R. M.; Spindler, H L

Abstract: Experiments have been carried out to characterize further the properties of a new laser-ablation-assisted-plasma-discharge source of metallic aluminium ions. Laser ablation is accomplished by focusing a KrF excimer laser (<1.2 J, 40 ns, 248 nm) onto a solid aluminium target with a fluence of approximately 10 J cm-2. Through gated optical emission spectroscopy, the laser ablation plume optical emission is observed to contain only aluminium neutral atom transitions after approximately 100 ns. With the application of a 3.6 kV, 760 A discharge, the neutral atom plume is transformed into a plasma with the emission dominated by Al+ and Al2+ ion transitions. Through time-resolved spectroscopy, emission intensity from the Al neutral species and the Al2+ ion species is observed to coincide with current peaks through the plasma. Spectroscopic measurements indicate an Al2+ electronic temperature of 3 eV (and an Al+ electronic temperature of 1 eV) which, since local thermodynamic equilibrium (LTE) is applicable for the observed emission, provide a free electron temperature of 1 to 3 eV. A simple LTE model suggests an electron temperature of 1.2 eV for equal Al+ and Al2+ ion fractions. A floating double Langmuir probe measurement 1 mm in front of the laser ablation spot indicates an electron temperature of roughly 1 eV and an ion density of approximately 5*1014 cm-3 during the second current lobe.

Extended frequency compensation of a diamagnetic loop

Sun, 31 Aug 1986 22:58:59 GMT

Title: Extended frequency compensation of a diamagnetic loop

Authors: Booske, J H; Getty, W. D.; Gilgenbach, R. M.

Abstract: A method of compensation for a diamagnetic loop that is magnetically coupled to a concentric stainless-steel vacuum vessel is presented. This compensation method accounts for imperfect magnetic coupling between the vessel eddy currents, the diamagnetic loop, and the plasma diamagnetic currents, and it also corrects for a finite loading resistance on the diamagnetic loop. A procedure for adjusting and calibrating the active-filter compensation circuit is presented. It can be applied to internal or external diamagnetic loops.