Electron Liquids in Semiconductor Quantum Structures (open access)

Electron Liquids in Semiconductor Quantum Structures

The groups led by Stormer and Pinczuk have focused this project on goals that seek the elucidation of novel many-particle effects that emerge in two-dimensional electron systems (2DES) as the result from fundamental quantum interactions. This experimental research is conducted under extreme conditions of temperature and magnetic field. From the materials point of view, the ultra-high mobility systems in GaAs/AlGaAs quantum structures continue to be at the forefront of this research. The newcomer materials are based on graphene, a single atomic layer of graphite. The graphene research is attracting enormous attention from many communities involved in condensed matter research. The investigated many-particle phenomena include the integer and fractional quantum Hall effect, composite fermions, and Dirac fermions, and a diverse group of electron solid and liquid crystal phases. The Stormer group performed magneto-transport experiments and far-infrared spectroscopy, while the Pinczuk group explores manifestations of such phases in optical spectra.
Date: May 25, 2009
Creator: Pinczuk, Aron
Object Type: Report
System: The UNT Digital Library
Photodiode-Based X-Ray Beam-Position Monitor With High Spatial-Resolution for the NSLS-II Beamlines (open access)

Photodiode-Based X-Ray Beam-Position Monitor With High Spatial-Resolution for the NSLS-II Beamlines

We developed a photodiode-based monochromatic X-ray beam-position monitor (X-BPM) with high spatial resolution for the project beamlines of the NSLS-II. A ring array of 32 Si PIN-junction photodiodes were designed for use as a position sensor, and a low-noise HERMES4 ASIC chip was integrated into the electronic readout system. A series of precision measurements to characterize electrically the Si-photodiode sensor and the ASIC chip demonstrated that the inherent noise is sufficiently below tolerance levels. Following up modeling of detector's performance, including geometrical optimization using a Gaussian beam, we fabricated and assembled a first prototype. In this paper, we describe the development of this new state-of-the-art X-ray BPM along the beamline, in particular, downstream from the monochromator.
Date: May 25, 2009
Creator: Yoon, P.S. & Siddons, D. P.
Object Type: Article
System: The UNT Digital Library
Correlation method for the measure of mask-induced line-edge roughness in extreme ultraviolet lithography (open access)

Correlation method for the measure of mask-induced line-edge roughness in extreme ultraviolet lithography

As critical dimensions for leading-edge semiconductor devices shrink, line-edge roughness (LER) requirements are pushing well into the single digit nanometer regime. At these scales many new sources of LER must be considered. In the case of extreme ultraviolet (EUV) lithography, modeling has shown the lithographic mask to be a source of significant concern. Here we present a correlation-based methodology for experimentally measuring the magnitude of mask contributors to printed LER. The method is applied to recent printing results from a 0.3 numerical aperture EUV microfield exposure tool. The measurements demonstrate that such effects are indeed present and of significant magnitude. The method is also used to explore the effects of illumination coherence and defocus and has been used to verify model-based predictions of mask-induced LER.
Date: May 25, 2009
Creator: Naulleau, Patrick
Object Type: Article
System: The UNT Digital Library
IMG ER: A System for Microbial Genome Annotation Expert Review and Curation (open access)

IMG ER: A System for Microbial Genome Annotation Expert Review and Curation

A rapidly increasing number of microbial genomes are sequenced by organizations worldwide and are eventually included into various public genome data resources. The quality of the annotations depends largely on the original dataset providers, with erroneous or incomplete annotations often carried over into the public resources and difficult to correct. We have developed an Expert Review (ER) version of the Integrated Microbial Genomes (IMG) system, with the goal of supporting systematic and efficient revision of microbial genome annotations. IMG ER provides tools for the review and curation of annotations of both new and publicly available microbial genomes within IMG's rich integrated genome framework. New genome datasets are included into IMG ER prior to their public release either with their native annotations or with annotations generated by IMG ER's annotation pipeline. IMG ER tools allow addressing annotation problems detected with IMG's comparative analysis tools, such as genes missed by gene prediction pipelines or genes without an associated function. Over the past year, IMG ER was used for improving the annotations of about 150 microbial genomes.
Date: May 25, 2009
Creator: Markowitz, Victor M.; Mavromatis, Konstantinos; Ivanova, Natalia N.; Chen, I-Min A.; Chu, Ken & Kyrpides, Nikos C.
Object Type: Report
System: The UNT Digital Library
EVENT TREE ANALYSIS AT THE SAVANNAH RIVER SITE: A CASE HISTORY (open access)

EVENT TREE ANALYSIS AT THE SAVANNAH RIVER SITE: A CASE HISTORY

At the Savannah River Site (SRS), a Department of Energy (DOE) installation in west-central South Carolina there is a unique geologic stratum that exists at depth that has the potential to cause surface settlement resulting from a seismic event. In the past the particular stratum in question has been remediated via pressure grouting, however the benefits of remediation have always been debatable. Recently the SRS has attempted to frame the issue in terms of risk via an event tree or logic tree analysis. This paper describes that analysis, including the input data required.
Date: May 25, 2009
Creator: Williams, R
Object Type: Article
System: The UNT Digital Library
Collins Mechanism Contributions to Single Spin Asymmetry (open access)

Collins Mechanism Contributions to Single Spin Asymmetry

We present recent developments on the single transverse spin physics, in particular, the Collins mechanism contributions in various hadronic reactions, such as semi-inclusive hadron production in DIS process, azimuthal distribution of hadron in high energy jet in pp collisions. We will demonstrate that the transverse momentum dependent and collinear factorization approaches are consistent with each other in the description of the Collins effects in the semi-inclusive hadron production in DIS process.
Date: May 25, 2009
Creator: Yuan,F.
Object Type: Article
System: The UNT Digital Library
Performance of exponential coupler in the SPS with LHC type beam for transverse broadband instability analysis (open access)

Performance of exponential coupler in the SPS with LHC type beam for transverse broadband instability analysis

We present the performance and limitations of the SPS exponential coupler [1] for transverse instability measurements with LHC type beam. Data were acquired in 2008 in the SPS in the time domain with a bandwidth of up to 2.5 GHz. The data were filtered to extract the time evolution of transverse oscillations within the less than 5 ns long LHC type bunches. We describe the data filtering techniques and show the limitations of the pick-up due to propagating modes.
Date: May 25, 2009
Creator: De Maria, R.; Fox, J. D.; Hofle, W.; Kotzian, G.; Rumolo, G.; Salvant, B. et al.
Object Type: Article
System: The UNT Digital Library