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Measuring Cluster Relaxedness

Description: When is a dark matter halo 'relaxed'? In our efforts to understand the structure of the universe, dark matter simulations have provided essential grounds for theoretical predictions. These simulations provide a wealth of ways of parameterizing and measuring the features of astronomical objects. It is these measurements on which we base comparisons of our world and our attempts to re-create it. One of the essential questions dark matter simulations help address is how dark matter halos evolve. H… more
Date: August 24, 2012
Creator: Moreland, Blythe & /SLAC, /Michigan U.
Partner: UNT Libraries Government Documents Department
open access

Using Dynamic Quantum Clustering to Analyze Hierarchically Heterogeneous Samples on the Nanoscale

Description: Dynamic Quantum Clustering (DQC) is an unsupervised, high visual data mining technique. DQC was tested as an analysis method for X-ray Absorption Near Edge Structure (XANES) data from the Transmission X-ray Microscopy (TXM) group. The TXM group images hierarchically heterogeneous materials with nanoscale resolution and large field of view. XANES data consists of energy spectra for each pixel of an image. It was determined that DQC successfully identifies structure in data of this type without p… more
Date: September 7, 2012
Creator: Hume, Allison & /SLAC, /Princeton U.
Partner: UNT Libraries Government Documents Department
open access

Research and Design of a Sample Heater for Beam Line 6-2c Transmission X-ray Microscope

Description: There exists a need for environmental control of samples to be imaged by the Transmission X-Ray Microscope (TXM) at the SSRLs Beam Line 6-2c. In order to observe heat-driven chemical or morphological changes that normally occur in situ, microscopes require an additional component that effectively heats a given sample without heating any of the microscope elements. The confinement of the heat and other concerns about the heaters integrity limit which type of heater is appropriate for the TXM. Th… more
Date: August 27, 2012
Creator: Policht, Veronica & /Loyola U., Chicago /SLAC
Partner: UNT Libraries Government Documents Department
open access

Magnet Lattice Design for the Transmission of Power Using Particle Beams

Description: As the amount of electricity generated by renewable energy sources continues to increase, the current method of power transmission will not serve as an adequate method for transmitting power over very long distances. A new method for transmitting power is proposed using particle beams in a storage ring. Particle beams offer an incredibly energy efficient alternative to transmission lines in transmitting power over very long distances. A thorough investigation of the magnet lattice design for th… more
Date: August 24, 2012
Creator: Marley, Daniel & /SLAC, /North Carolina State U.
Partner: UNT Libraries Government Documents Department
open access

Investigating the Magnetorotational Instability with Dedalus, and Open-Souce Hydrodynamics Code

Description: The magnetorotational instability is a fluid instability that causes the onset of turbulence in discs with poloidal magnetic fields. It is believed to be an important mechanism in the physics of accretion discs, namely in its ability to transport angular momentum outward. A similar instability arising in systems with a helical magnetic field may be easier to produce in laboratory experiments using liquid sodium, but the applicability of this phenomenon to astrophysical discs is unclear. To expl… more
Date: August 31, 2012
Creator: Burns, Keaton J & /UC, Berkeley, aff SLAC
Partner: UNT Libraries Government Documents Department
open access

Design & Fabrication of a High-Voltage Photovoltaic Cell

Description: Silicon photovoltaic (PV) cells are alternative energy sources that are important in sustainable power generation. Currently, applications of PV cells are limited by the low output voltage and somewhat low efficiency of such devices. In light of this fact, this project investigates the possibility of fabricating high-voltage PV cells on float-zone silicon wafers having output voltages ranging from 50 V to 2000 V. Three designs with different geometries of diffusion layers were simulated and com… more
Date: September 5, 2012
Creator: Felder, Jennifer & /SLAC, /North Carolina State U.
Partner: UNT Libraries Government Documents Department
open access

An Improved Technique for Increasing the Accuracy of Photometrically Determined Redshifts for ___Blended___ Galaxies

Description: The redshift of a galaxy can be determined by one of two methods; photometric or spectroscopic. Photometric is a term for any redshift determination made using the magnitudes of light in different filters. Spectroscopic redshifts are determined by measuring the absorption spectra of the object then determining the difference in wavelength between the 'standard' absorption lines and the measured ones, making it the most accurate of the two methods. The data for this research was collected from S… more
Date: August 24, 2012
Creator: Parker, Ashley Marie & /SLAC, /Marietta Coll.
Partner: UNT Libraries Government Documents Department
open access

A Comparison of Image Quality Evaluation Techniques for Transmission X-Ray Microscopy

Description: Beamline 6-2c at Stanford Synchrotron Radiation Lightsource (SSRL) is capable of Transmission X-ray Microscopy (TXM) at 30 nm resolution. Raw images from the microscope must undergo extensive image processing before publication. Since typical data sets normally contain thousands of images, it is necessary to automate the image processing workflow as much as possible, particularly for the aligning and averaging of similar images. Currently we align images using the 'phase correlation' algorithm,… more
Date: August 31, 2012
Creator: Bolgert, Peter J & /SLAC, /Marquette U.
Partner: UNT Libraries Government Documents Department
open access

Representing Range Compensators with Computational Geometry in TOPAS

Description: In a proton therapy beamline, the range compensator modulates the beam energy, which subsequently controls the depth at which protons deposit energy. In this paper, we introduce two computational representations of range compensator. One of our compensator representations, which we refer to as a subtraction solid-based range compensator, precisely represents the compensator. Our other representation, the 3D hexagon-based range compensator, closely approximates the compensator geometry. We have … more
Date: September 7, 2012
Creator: Iandola, Forrest N. & /Illinois U., Urbana /SLAC
Partner: UNT Libraries Government Documents Department
open access

Extracting bb Higgs Decay Signals using Multivariate Techniques

Description: For low-mass Higgs boson production at ATLAS at {radical}s = 7 TeV, the hard subprocess gg {yields} h{sup 0} {yields} b{bar b} dominates but is in turn drowned out by background. We seek to exploit the intrinsic few-MeV mass width of the Higgs boson to observe it above the background in b{bar b}-dijet mass plots. The mass resolution of existing mass-reconstruction algorithms is insufficient for this purpose due to jet combinatorics, that is, the algorithms cannot identify every jet that results… more
Date: August 28, 2012
Creator: Smith, W Clarke & /SLAC, /George Washington U.
Partner: UNT Libraries Government Documents Department
open access

X-Ray Emission Spectrometer Design with Single-Shot Pump-Probe and Resonant Excitation Capabilities

Description: Core-level spectroscopy in the soft X-ray regime is a powerful tool for the study of chemical bonding processes. The ultrafast, ultrabright X-ray pulses generated by the Linac Coherent Light Source (LCLS) allow these reactions to be studied in greater detail than ever before. In this study, we investigated a conceptual design of a spectrometer for the LCLS with imaging in the non-dispersive direction. This would allow single-shot collection of X-ray emission spectroscopy (XES) measurements with… more
Date: August 28, 2012
Creator: Spoth, Katherine & /SUNY, Buffalo /SLAC
Partner: UNT Libraries Government Documents Department
open access

Infrared Spectroscope for Electron Bunch-length Measurement: Heat Sensor Parameters Analysis

Description: The Linac Coherent Light Source (LCLS) is used for many experiments. Taking advantage of the free electron laser (FEL) process, scientists of various fields perform experiments of all kind. Some for example study protein folding; other experiments are more interested in the way electrons interact with the molecules before they are destroyed. These experiments among many others have very little information about the electrons x-ray produced by the FEL, except that the FEL is using bunches less t… more
Date: September 5, 2012
Creator: Domgmo-Momo, Gilles & /SLAC, /Towson U.
Partner: UNT Libraries Government Documents Department
open access

Characterizing the Nanoscale Layers of Tomorrow___s Electronics An Application of Fourier Analysis

Description: Thin film applications are of great interest to the semiconductor industry due to the important role they play in cutting edge technology such as thin film solar cells. X-Ray Reflectivity (XRR) characterizes thin films in a non-destructive and efficient manner yet complications exist in extracting these characteristics from raw XRR data. This study developed and tested two different algorithms to extract quantity of layers and thickness information on the nanometer scale from XRR data. It was c… more
Date: August 24, 2012
Creator: Payne, Christopher Bishop & /SLAC, /Princeton U.
Partner: UNT Libraries Government Documents Department
open access

Channeling through Bent Crystals

Description: Bent crystals have demonstrated potential for use in beam collimation. A process called channeling is when accelerated particle beams are trapped by the nuclear potentials in the atomic planes within a crystal lattice. If the crystal is bent then the particles can follow the bending angle of the crystal. There are several different effects that are observed when particles travel through a bent crystal including dechanneling, volume capture, volume reflection and channeling. With a crystal place… more
Date: September 7, 2012
Creator: Mack, Stephanie & /SLAC, /Ottawa U.
Partner: UNT Libraries Government Documents Department
open access

Dark Photon Search at BABAR

Description: Presented is the current progress of a search for the signature of a dark photon or new particle using the BaBar data set. We search for the processes e{sup +}e{sup -} {yields} {gamma}{sub ISR}A{prime},A{prime} {yields} e{sup +}e{sup -} and e{sup +}e{sup -} {yields} {gamma}{sub ISR}{gamma}, {gamma} {yields} A{prime},A{prime} {yields} e{sup +}e{sup -}, where {gamma}{sub ISR} is an initial state radiated photon of energy E{sub {gamma}} >= 1 GeV. Twenty-five sets of Monte Carlo, simulating e{su… more
Date: September 7, 2012
Creator: Greenwood, Ross N & /SLAC, /MIT
Partner: UNT Libraries Government Documents Department
open access

Bunch Profiling Using a Rotating Mask

Description: The current method for measuring profiles of proton bunches in accelerators is severely lacking. One must dedicate a great deal of time and expensive equipment to achieve meaningful results. A new method to complete this task uses a rotating mask with slots of three different orientations to collect this data. By scanning over the beam in three different directions, a complete profile for each bunch is built in just seconds, compared to the hours necessary for the previous method. This design w… more
Date: August 24, 2012
Creator: Miller, Mitchell & /SLAC /IIT, Chicago
Partner: UNT Libraries Government Documents Department
open access

INSPIRE and SPIRES Log File Analysis

Description: SPIRES, an aging high-energy physics publication data base, is in the process of being replaced by INSPIRE. In order to ease the transition from SPIRES to INSPIRE it is important to understand user behavior and the drivers for adoption. The goal of this project was to address some questions in regards to the presumed two-thirds of the users still using SPIRES. These questions are answered through analysis of the log files from both websites. A series of scripts were developed to collect and int… more
Date: August 31, 2012
Creator: Adams, Cole & /SLAC, /Wheaton Coll.
Partner: UNT Libraries Government Documents Department
open access

Section on Supernova Remnants and Cosmic Rays of the White Paper on the Status and Future of Ground-Based Gamma-Ray Astronomy

Description: This is a report on the findings of the SNR/cosmic-ray working group for the white paper on the status and future of ground-based gamma-ray astronomy. The white paper is an APS commissioned document, and the overall version has also been released and can be found on astro-ph. This detailed section of the white paper discusses the status of past and current attempts to observe shell-type supernova remnants and diffuse emission from cosmic rays at GeV-TeV energies. We concentrate on the potential… more
Date: November 9, 2011
Creator: Pohl, M.; U., /Iowa State; Abdo, Aous A.; U., /Michigan State; Atoyan, A.; U., /McGill et al.
Partner: UNT Libraries Government Documents Department
open access

FRW Solutions and Holography from Uplifted AdS/CFT

Description: Starting from concrete AdS/CFT dual pairs, one can introduce ingredients which produce cosmological solutions, including metastable de Sitter and its decay to non-accelerating FRW. We present simple FRW solutions sourced by magnetic flavor branes and analyze correlation functions and particle and brane dynamics. To obtain a holographic description, we exhibit a time-dependent warped metric on the solution and interpret the resulting redshifted region as a Lorentzian low energy effective field t… more
Date: February 15, 2012
Creator: Dong, Xi; Horn, Bart; /Stanford U., ITP /Stanford U., Phys. Dept. /SLAC; Matsuura, Shunji; /Santa Barbara, KITP /Stanford U., ITP /Stanford U., Phys. Dept. /SLAC; Silverstein, Eva et al.
Partner: UNT Libraries Government Documents Department
open access

New Sources of Gravitational Waves During Inflation

Description: We point out that detectable inflationary tensor modes can be generated by particle or string sources produced during inflation, consistently with the requirements for inflation and constraints from scalar fluctuations. We show via examples that this effect can dominate over the contribution from quantum fluctuations of the metric, occurring even when the inflationary potential energy is too low to produce a comparable signal. Thus a detection of tensor modes from inflation does not automatical… more
Date: February 15, 2012
Creator: Senatore, Leonardo; Silverstein, Eva; /Stanford U., Phys. Dept. /SLAC; Zaldarriaga, Matias & /Princeton, Inst. Advanced Study
Partner: UNT Libraries Government Documents Department
open access

Resolving Lifshitz Horizons

Description: Via the AdS/CFT correspondence, ground states of field theories at finite charge density are mapped to extremal black brane solutions. Studies of simple gravity + matter systems in this context have uncovered wide new classes of extremal geometries. The Lifshitz metrics characterizing field theories with non-trivial dynamical critical exponent z {ne} 1 emerge as one common endpoint in doped holographic toy models. However, the Lifshitz horizon exhibits mildly singular behaviour - while curvatur… more
Date: April 24, 2012
Creator: Harrison, Sarah; Kachru, Shamit; Wang, Huajia & /Stanford U., ITP /Stanford U., Phys. Dept. /SLAC
Partner: UNT Libraries Government Documents Department
open access

Comparing the Calibration and Simulation Data of the Cryogenic Dark Matter Search

Description: The Cryogenic Dark Matter Search, or CDMS, collaboration is preparing a new experiment called SuperCDMS. CDMS uses Germanium detectors to attempt the direct detection of dark matter. To do this, they measure the ionization and heat produced during an event where a WIMP scatters off of germanium crystal lattice. To prepare for the experiment the detectors are calibrated with various radioactive sources. The response of the detectors is also modeled by a Monte Carlo simulation. These simulations … more
Date: June 22, 2011
Creator: DiFranzo, Anthony & /SLAC, /Rensselaer Poly.
Partner: UNT Libraries Government Documents Department
open access

A Simple Harmonic Universe

Description: We explore simple but novel bouncing solutions of general relativity that avoid singularities. These solutions require curvature k = +1, and are supported by a negative cosmological term and matter with -1 < w < -1 = 3. In the case of moderate bounces (where the ratio of the maximal scale factor a{sub +} to the minimal scale factor a{sub -} is {Omicron}(1)), the solutions are shown to be classically stable and cycle through an infinite set of bounces. For more extreme cases with large a{s… more
Date: December 14, 2011
Creator: Graham, Peter W.; /Stanford U., ITP; Horn, Bart; Kachru, Shamit; /Stanford U., ITP /SLAC; Rajendran, Surjeet et al.
Partner: UNT Libraries Government Documents Department
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