113 Matching Results

Search Results

Results: 1 - 24 next
open access

Synthesis of silicon and germanium nanowires.

Description: The vapor-liquid-solid growth process for synthesis of group-IV semiconducting nanowires using silane, germane, disilane and digermane precursor gases has been investigated. The nanowire growth process combines in situ gold seed formation by vapor deposition on atomically clean silicon (111) surfaces, in situ growth from the gaseous precursor(s), and real-time monitoring of nanowire growth as a function of temperature and pressure by a novel optical reflectometry technique. A significant depend… more
Date: November 1, 2007
Creator: Clement, Teresa J. (Arizona State University) & Hsu, Julia W. P.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Germanium: From Its Discovery to SiGe Devices

Description: Germanium, element No.32, was discovered in 1886 by Clemens Winkler. Its first broad application was in the form of point contact Schottky diodes for radar reception during WWII. The addition of a closely spaced second contact led to the first all-solid-state electronic amplifier device, the transistor. The relatively low bandgap, the lack of a stable oxide and large surface state densities relegated germanium to the number 2 position behind silicon. The discovery of the lithium drift process, … more
Date: June 14, 2006
Creator: Haller, E.E.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

A search for particle dark matter using cryogenic germanium and silicon detectors in the one- and two- tower runs of CDMS-II at Soudan

Description: Images of the Bullet Cluster of galaxies in visible light, X-rays, and through gravitational lensing confirm that most of the matter in the universe is not composed of any known form of matter. The combined evidence from the dynamics of galaxies and clusters of galaxies, the cosmic microwave background, big bang nucleosynthesis, and other observations indicates that 80% of the universe's matter is dark, nearly collisionless, and cold. The identify of the dar, matter remains unknown, but weakly … more
Date: April 1, 2008
Creator: Ogburn, Reuben Walter, IV
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries Government Documents Department
open access

The Ability of the United States Federal Radiological Monitoring and Assessment Center to Collect and Disseminate Environmental Measurements during Radiological Emergencies

Description: The Federal Radiological Monitoring and Assessment Center (FRMAC) is the United States’ response organization for radiological emergencies. The FRMAC is structured as an operations center and employs the combined resources of several federal agencies to respond to any disaster resulting in the release of radioactivity. The mission of the FRMAC is to support state and local authorities in the gathering of environmental data using an array of survey equipment ranging from alpha probes, beta/gamma… more
Date: April 30, 2007
Creator: Essex, Craig Marianno and James
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Recent Developments in Neutrino Science: A Whole Lot About Almost Nothing

Description: Results from Super-K, SNO, and KamLAND provide strong evidence that neutrinos undergo flavor-changing oscillations and therefore have non-zero mass. The {nu}-disappearance observations by KamLAND, assuming CPT conservation, point to matter enhanced (MSW) oscillations with large mixing angles as the solution to the solar neutrino problem--a result consistent with the MSW parameters recently defined by these experiments. This requires that the observed neutrino flavors (e, {mu}, and tau) are not … more
Date: August 22, 2005
Creator: Norman, E B
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Resonant Ultrasound Studies of Complex Transition Metal Oxides

Description: Department of Energy EPSCoR The University of Mississippi Award: DE-FG02-04ER46121 Resonant Ultrasound Spectroscopy Studies of Complex Transition Metal Oxides The central thrust of this DOE funded research program has been to apply resonant ultrasound spectroscopy (RUS), an elegant and efficient method for determining the elastic stiffness constants of a crystal, to the complex and poorly understood class of materials known as transition metal oxides (TMOs). Perhaps the most interesting and cha… more
Date: August 18, 2008
Creator: Bass, Henry & Gladden, J. R.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Fission Product Monitoring of TRISO Coated Fuel For The Advanced Gas Reactor -1 Experiment

Description: The US Department of Energy has embarked on a series of tests of TRISO-coated particle reactor fuel intended for use in the Very High Temperature Reactor (VHTR) as part of the Advanced Gas Reactor (AGR) program. The AGR-1 TRISO fuel experiment, currently underway, is the first in a series of eight fuel tests planned for irradiation in the Advanced Test Reactor (ATR) located at the Idaho National Laboratory (INL). The AGR-1 experiment reached a peak compact averaged burn up of 9% FIMA with no kn… more
Date: September 1, 2008
Creator: Scates, Dawn M.; Hartwell, John (Jack) K & Walter, John B.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Measurment of Depositing and Bombarding Species Involved in the Plasma Production of Amorphous Silicon and Silicon/Germanium Solar Cells: Annual Technical Report, 1 June 2002 - 31 May 2005

Description: The objective of this study is to measure the molecular species that lead to the growth of hydrogenated amorphous silicon (a-Si:H) and microcrystalline silicon (..mu..c-Si) photovoltaic (PV) devices from RF discharges. Neutral radicals produce most of the film growth during this PV-device production, and, by implication, radicals primarily determine the device structure and electrical characteristics. The most important feature of the present experiment is thus the measurement of neutral-radica… more
Date: June 1, 2006
Creator: Gallagher, A.; Rozsa, K.; Horvath, P. & Kujundcik, D.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Gamma Ray Multiplicity of 252Cf Spontaneous Fission using LiBerACE

Description: We are studying the gamma ray and neutron multiplicity of various fission processes, beginning with the spontaneous fission of {sup 252}Cf, for a variety of basic and applied science purposes. The Livermore-Berkeley Array for Collaborative Experiments (LiBerACE) consists of six high-purity germanium Clover detectors (HPGe) each enclosed by an array of 16 bismuth-germanate (BGO) detectors. These detectors were arranged in a cubic pattern around a 1 {micro}Ci {sup 252}Cf source to attempt to cove… more
Date: January 15, 2008
Creator: Bleuel, D L; Bernstein, L A; Burke, J T; Heffner, M D; Norman, E B; Scielzo, N D et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Thermoelasticity of SSP Materials: An Integrated Ultrasonic and X-radiation Study

Description: It has been a very productive year for accomplishing the tasks outlined in the original proposal. Quite a few crystalline materials [tantalum (Ta), molybdenum (Mo), cerium (Ce) beryllium (Be)] and amorphous materials [zirconium tungstate (ZrW2O8), SiO2, and germanium diselenide (GeSe2) glasses] have been assessed at high pressures up to 12 GPa and acoustic velocities and densities have been obtained simultaneously using our unique technique. Major activities include sample preparation, high pre… more
Date: July 29, 2008
Creator: Li, Baosheng
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Gamma-Ray Imaging With Coaxial HPGe Detector

Description: We report on the first experimental demonstration of Compton imaging of gamma rays with a single coaxial high-purity germanium (HPGe) detector. This imaging capability is realized by two-dimensional segmentation of the outside contact in combination with digital pulse-shape analysis, which enables to image gamma rays in 4{pi} without employing a collimator. We are able to demonstrate the ability to image the 662keV gamma ray from a {sup 137}Cs source with preliminary event selection with an ang… more
Date: April 12, 2005
Creator: Niedermayr, T.; Vetter, K.; Mihailescu, L.; Schmid, G. J.; Beckedahl, D.; Kammeraad, J. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Chemical Bonding, Interfaces and Defects in Hafnium Oxide/Germanium Oxynitride Gate Stacks on Ge (100)

Description: Correlations among interface properties and chemical bonding characteristics in HfO{sub 2}/GeO{sub x}N{sub y}/Ge MIS stacks were investigated using in-situ remote nitridation of the Ge (100) surface prior to HfO{sub 2} atomic layer deposition (ALD). Ultra thin ({approx}1.1 nm), thermally stable and aqueous etch-resistant GeO{sub x}N{sub y} interfaces layers that exhibited Ge core level photoelectron spectra (PES) similar to stoichiometric Ge{sub 3}N{sub 4} were synthesized. To evaluate GeO{sub … more
Date: October 31, 2008
Creator: Oshima, Yasuhiro; /Stanford U., Materials Sci. Dept.; Sun, Yun; /SLAC, SSRL; Kuzum, Duygu; U., /Stanford et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

X-ray Measurements of a Thermo Scientific P385 DD Neutron Generator

Description: Idaho National Laboratory is experimenting with electrical neutron generators, as potential replacements for californium-252 radioisotopic neutron sources in its PINS prompt gamma-ray neutron activation analysis (PGNAA) system for the identification of military chemical warfare agents and explosives. In addition to neutron output, we have recently measured the x-ray output of the Thermo Scientific P385 deuterium-deuterium neutron generator. X-rays are a normal byproduct from a neutron generator… more
Date: August 1, 2001
Creator: Seabury, E. H.; Chichester, D. L.; Caffrey, A. J.; Simpson, J.; Lemchak, M. & Wharton, C. J.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

A Germanium-Based, Coded Aperture Imager

Description: We describe a coded-aperture based, gamma-ray imager that uses a unique hybrid germanium detector system. A planar, germanium strip detector, eleven millimeters thick is followed by a coaxial detector. The 19 x 19 strip detector (2 mm pitch) is used to determine the location and energy of low energy events. The location of high energy events are determined from the location of the Compton scatter in the planar detector and the energy is determined from the sum of the coaxial and planar energies… more
Date: October 31, 2001
Creator: Ziock, K P; Madden, N; Hull, E; William, C; Lavietes, T & Cork, C
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Demonstration of an Electronic Gamma-Rau Spectrum Synthesizer

Description: The goal of this demonstration was to show that it is possible to generate electronic signals that can accurately mimic the signals that are produced by a high-purity germanium (HPGe) gamma-ray detector. As an example of this fidelity, we decided to show that it was possible to perform a complex, multiplet-resolution analysis of a portion of the spectrum acquired from the gamma-ray spectrum synthesizer. We further showed that the results of this analysis were consistent with what would be obtai… more
Date: April 3, 2002
Creator: Luke, S J
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

a-SiGe:H Materials and Devices Deposited by Hot Wire CVD Using a Tantalum Filament Operated at Low Temperature

Description: We report the deposition of improved hydrogenated amorphous silicon germanium (a-SiGe:H) films by the hot wire CVD (HWCVD) technique using a tantalum filament operating at a low temperature. We gauge the material quality of the a-SiGe:H films by comparing infrared, small angle X-ray scattering (SAXS), photocapacitance, and conductivity measurements to earlier results, and fabricate single-junction n-i-p solar cell devices using these i-layers.
Date: February 1, 2005
Creator: Mahan, A. H.; Xu, Y.; Gedvilas, L. M.; Reedy, R. C.; Williamson, D. L.; Datta, S. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Structural and Electronic Properties of Isolated Nanodiamonds: A Theoretical Perspective

Description: Nanometer sized diamond has been found in meteorites, proto-planetary nebulae and interstellar dusts, as well as in residues of detonation and in diamond films. Remarkably, the size distribution of diamond nanoparticles appears to be peaked around 2-5 nm, and to be largely independent of preparation conditions. Using ab-initio calculations, we have shown that in this size range nanodiamond has a fullerene-like surface and, unlike silicon and germanium, exhibit very weak quantum confinement effe… more
Date: September 9, 2004
Creator: Raty, J & Galli, G
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Development of an "Isotopic" Pulser

Description: We have developed a pulser that is able to generate a simulated signal from a high-purity germanium (HPGe) detector for various plutonium isotopes. In this paper we describe the development of an ''isotopics'' pulser for the simulation of signals that are produced by an HPGe detector. The present pulser generates the waveforms that are produced by an HPGe detector both before and after the preamplifier. These signals have been input into a normal MCA and the result closely simulates a genuine p… more
Date: June 4, 2002
Creator: Luke, S. J.; Schmid, G.; Beckedahl, D.; Pohl, B. & White, G.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

The Novel Synthesis of Silicon and Germanium Nanocrystallites

Description: Interest in the synthesis of semiconductor nanoparticles has been generated by their unusual optical and electronic properties arising from quantum confinement effects. We have synthesized silicon and germanium nanoclusters by reacting Zintl phase precursors with either silicon or germanium tetrachloride in various solvents. Strategies have been investigated to stabilize the surface, including reactions with RLi and MgBrR (R = alkyl). This synthetic method produces group IV nanocrystals with pa… more
Date: April 3, 2001
Creator: Kauzlarich, S. M.; Liu, Q.; Yin, S. C.; Lee, W. H. & Taylor, B.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

NSLS 2009 Activity Report

Description: 2009 was an incredibly exciting year for light sources at Brookhaven. The National Synchrotron Light Source (NSLS) hosted more than 2,200 visiting researchers, who, along with the about 50 members of our scientific staff, produced a total of 957 publications - about 20 percent of which appeared in premier journals. Covering topics ranging from Alzheimer's disease detection to ethanol-powered fuel cells, a sampling of these findings can be found in this Activity Report. We've also seen the resur… more
Date: May 1, 2009
Creator: K., Nasta & R., Mona
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Gamma-ray multiplicity measurement of the spontaneous fission decay of 252Cf in a segmented HPGe/BGO detector array

Description: Coincident {gamma} rays from a {sup 252}Cf source were measured using an array of six segmented high-purity germanium (HPGe) Clover detectors each enclosed by 16 bismuth-germanate (BGO) detectors. The detectors were arranged in a cubic pattern around a 1 {micro}Ci {sup 252}Cf source to cover a large solid angle for {gamma}-ray measurement with a reasonable reconstruction of the multiplicity. Neutron multiplicity was determined in certain cases by identifying the prompt {gamma} rays from individ… more
Date: April 23, 2008
Creator: Bleuel, D L; Bernstein, L A; Burke, J T; Gibelin, J; Heffner, M D; Mintz, J et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

CryoFree Final Report

Description: CryoFree, a gamma-ray spectrometer, has been built and successfully tested. This instrument is based on a planar germanium semiconductor detector and is optimized for high-resolution spectroscopy in the range of a 30 keV to a few hundred keV to detect U and Pu. The spectrometer is cooled with a mechanical cryocooler that obviates the need for liquid cryogen. Furthermore, the instrument is battery powered. The combination of mechanical cooling and battery operation allows high-resolution spectro… more
Date: November 7, 2006
Creator: Burks, M
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Final Report for Monitoring of Reactor Antineutrinos with Compact Germanium Detectors

Description: This 2008 NCMR project has pursued measurement of the antineutrino-nucleus coherent scattering interaction using a low-energy threshold germanium gamma-ray spectrometer of roughly one-half kilogram total mass. These efforts support development of a compact system for monitoring the antineutrino emission from nuclear reactor cores. Such a monitoring system is relevant to nuclear safeguards and nuclear non-proliferation in general by adding a strong method for assuring quantitative material balan… more
Date: July 1, 2009
Creator: Orrell, John L. & Collar, J. I.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

MOLECULAR DESIGN OF COLLOIDS IN SUPERCRITICAL FLUIDS

Description: The environmentally benign, non-toxic, non-flammable fluids water and carbon dioxide (CO2) are the two most abundant and inexpensive solvents on earth. Emulsions of these fluids are of interest in many industrial processes, as well as CO2 sequestration and enhanced oil recovery. Until recently, formation of these emulsions required stabilization with fluorinated surfactants, which are expensive and often not environmentally friendly. In this work we overcame this severe limitation by developing… more
Date: April 6, 2009
Creator: Johnston, Keith P.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
Back to Top of Screen