Soft X-Ray and Vacuum Ultraviolet Based Spectroscopy of the Actinides (open access)

Soft X-Ray and Vacuum Ultraviolet Based Spectroscopy of the Actinides

The subjects of discussion included: VUV photoelectron spectroscopy, X-ray photoelectron spectroscopy, Synchrotron-radiation-based photoelectron spectroscopy, Soft x-ray absorption spectroscopy, Soft x-ray emission spectroscopy, Inverse photoelectron spectroscopy, Bremstrahlung Isochromat Spectroscopy, Low energy IPES, Resonant inverse photoelectron spectroscopy.
Date: March 17, 2011
Creator: Tobin, J. G.
System: The UNT Digital Library
The Dawn of Nuclear Photonics with Laser-based Gamma-rays (open access)

The Dawn of Nuclear Photonics with Laser-based Gamma-rays

A renaissance in nuclear physics is occurring around the world because of a new kind of incredibly bright, gamma-ray light source that can be created with short pulse lasers and energetic electron beams. These highly Mono-Energetic Gamma-ray (MEGa-ray) sources produce narrow, laser-like beams of incoherent, tunable gamma-rays and are enabling access and manipulation of the nucleus of the atom with photons or so called 'Nuclear Photonics'. Just as in the early days of the laser when photon manipulation of the valence electron structure of the atom became possible and enabling to new applications and science, nuclear photonics with laser-based gamma-ray sources promises both to open up wide areas of practical isotope-related, materials applications and to enable new discovery-class nuclear science. In the United States, the development of high brightness and high flux MEGa-ray sources is being actively pursued at the Lawrence Livermore National Laboratory in Livermore (LLNL), California near San Francisco. The LLNL work aims to create by 2013 a machine that will advance the state of the art with respect to source the peak brightness by 6 orders of magnitude. This machine will create beams of 1 to 2.3 MeV photons with color purity matching that of common lasers. …
Date: March 17, 2011
Creator: Barty, C J
System: The UNT Digital Library
Application of the Software as a Service Model to the Control of Complex Building Systems (open access)

Application of the Software as a Service Model to the Control of Complex Building Systems

In an effort to create broad access to its optimization software, Lawrence Berkeley National Laboratory (LBNL), in collaboration with the University of California at Davis (UC Davis) and OSISoft, has recently developed a Software as a Service (SaaS) Model for reducing energy costs, cutting peak power demand, and reducing carbon emissions for multipurpose buildings. UC Davis currently collects and stores energy usage data from buildings on its campus. Researchers at LBNL sought to demonstrate that a SaaS application architecture could be built on top of this data system to optimize the scheduling of electricity and heat delivery in the building. The SaaS interface, known as WebOpt, consists of two major parts: a) the investment& planning and b) the operations module, which builds on the investment& planning module. The operational scheduling and load shifting optimization models within the operations module use data from load prediction and electrical grid emissions models to create an optimal operating schedule for the next week, reducing peak electricity consumption while maintaining quality of energy services. LBNL's application also provides facility managers with suggested energy infrastructure investments for achieving their energy cost and emission goals based on historical data collected with OSISoft's system. This paper describes these …
Date: March 17, 2011
Creator: Stadler, Michael; Donadee, Jonathan; Marnay, Chris; Mendes, Goncalo; Appen, Jan von; Megel, Oliver et al.
System: The UNT Digital Library
A Comparison of Three Voting Methods for Bagging with the MLEM2 Algorithm (open access)

A Comparison of Three Voting Methods for Bagging with the MLEM2 Algorithm

This paper presents results of experiments on some data sets using bagging on the MLEM2 rule induction algorithm. Three different methods of ensemble voting, based on support (a non-democratic voting in which ensembles vote with their strengths), strength only (an ensemble with the largest strength decides to which concept a case belongs) and democratic voting (each ensemble has at most one vote) were used. Our conclusions are that though in most cases democratic voting was the best, it is not significantly better than voting based on support. The strength voting was the worst voting method.
Date: March 17, 2010
Creator: Cohagan, Clinton; Grzymala-Busse, Jerzy W. & Hippe, Zdzislaw S.
System: The UNT Digital Library
Investigation of the Unoccupied Electronic Structure of UO2 with Bermstrahlung Isochromat Spectroscopy and X-Ray Absorption Spectroscopy (open access)

Investigation of the Unoccupied Electronic Structure of UO2 with Bermstrahlung Isochromat Spectroscopy and X-Ray Absorption Spectroscopy

UO{sub 2} is an important nuclear fuel for electrical power generation. Global goal : Actinides (5f electron systems) exhibit fascinating physical and chemical properties, due to 5f electron correlation, including the highly radioactive systems such as Pu. Onsite Instrumentation: A spectroscopic system containing spin resolved photoelectron spectroscopy (SRPES) and bremsstrahlung isochromat spectroscopy (BIS) has been built and commissioned at LLNL. ALS Instrumentation: The XAS was done on Beamline 8. Both Total Electron Yield (TEY) and Total Fluorescence Yield (TFY) were used. TFY is less surface sensitive than TEY. A combined experimental and theoretical study of Uranium Dioxide has been performed, including XAS, BIS, XPS and spectral simulations. The Conduction Bands or Unoccupied Density of States (UDOS) of UO{sub 2} are shown to be divided into two parts, the lower region being U5f-O2p and the upper region U6d-O2p. This means that UO{sub 2} is an f-f Mott Insulator, electron-correlated system. The keys to success with the XAS were the (1) the utilization of both TEY and TFY and (2) the accurate co-location of the uranium and oxygen states, which in turn hinged upon a proper calibration of the gratings of the beamline monochromator. The calibration of the gratings was greatly aided …
Date: March 17, 2011
Creator: Tobin, J. G.; Yu, S. W.; Crowhurst, J. C.; Sharma, S.; Dewhurst, J. K.; Olalde-Velasco, P. et al.
System: The UNT Digital Library
Confinement of antiprotons in the electrostatic space charge of positrons in a model of the ALPHA antihydrogen trap (open access)

Confinement of antiprotons in the electrostatic space charge of positrons in a model of the ALPHA antihydrogen trap

This article details the equilibrium of a positron plasma in a model of the ALPHA apparatus that is computed using a finite-difference method. The positron plasma in the model extends to axial magnetic mirrors in absence of an octupole field. Formation of a three-dimensional electrostatic potential well is found to occur self-consistently. Well depths under various conditions are evaluated. Also, the equilibrium with an antiproton plasma confined in the potential well is computed.
Date: March 17, 2016
Creator: Lane, Ryan A. & Ordonez, Carlos A.
System: The UNT Digital Library