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Solid State NMR Investigations of Chain Dynamics and Network Order in Model Poly(dimethylsiloxane) Elastomers (open access)

Solid State NMR Investigations of Chain Dynamics and Network Order in Model Poly(dimethylsiloxane) Elastomers

This work is at a relatively early stage, however it has been demonstrated that we can reliably probe basic network architectures using the MQ-NMR technique. The initial results are in good agreement with what is known from standard network theory and will serve as a basis for the study of progressively increasing structural complexity in Siloxane network systems.
Date: December 9, 2010
Creator: Lewicki, J P; Mayer, B P; Wilson, T S; Chinn, S C & Maxwell, R S
System: The UNT Digital Library
Main Injector Particle Production Experiment (MIPP) at Fermilab (open access)

Main Injector Particle Production Experiment (MIPP) at Fermilab

The Main Injector Particle Production Experiment at Fermilab uses particle beams of charged pions, kaons, proton and anti-proton with beam momenta of 5 to 90 GeV/c and thin targets spanning the periodic table from (liquid) hydrogen to uranium to measure particle production cross sections in a full acceptance spectrometer with charged particle identification for particles from 0.1 to 120 GeV/c using Time Projection Chamber, Time of Flight, multicell Cherenkov, and Ring Imaging Cherenkov detectors and Calorimeter for neutrons. Particle production using 120 GeV/c protons from Main Injector on the MINOS target was also measured. We describe the physics motivation to perform such cross section measurements and highlight the impact of hadronic interaction data on neutrino physics. Recent results on forward neutron cross sections and analysis of MINOS target data are also presented.
Date: December 9, 2010
Creator: Mahajan, Sonam
System: The UNT Digital Library
MiniBooNE "Windows on the Universe" (open access)

MiniBooNE "Windows on the Universe"

Progress in the last few decades has left neutrino physics with several vexing issues. Among them are the following questions: (1) Why are lepton mixing angles so different from those in the quark sector? (2) What is the most probable range of the reactor mixing angle? (3) Is the atmospheric mixing angle maximal? (4) What is the number of fermion generations? These are some of the issues that neutrino science hopes to study; this article will explore these questions as part of a more general scientific landscape, and will discuss the part MiniBooNE might play in this exploration. We discuss the current state of measurements taken by MiniBooNE, and emphasize the uniqueness of neutrino oscillations as an important probe into the 'Windows on the Universe.'
Date: December 9, 2010
Creator: Stefanski, Ray
System: The UNT Digital Library
Electrospun a-Si using Liquid Silane/Polymer Inks (open access)

Electrospun a-Si using Liquid Silane/Polymer Inks

Amorphous silicon nanowires (a-SiNWs) were prepared by electrospinning cyclohexasilane (Si{sub 6}H{sub 12}) admixed with polymethylmethacrylate (PMMA) in toluene. Raman spectroscopy characterization of these wires (d {approx} 50-2000 nm) shows 350 C treatment yields a-SiNWs. Porous a-SiNWs are obtained using a volatile polymer.
Date: December 9, 2010
Creator: Schulz, Doug
System: The UNT Digital Library
Laboratory Calibration of Density-Dependent Lines in the EUV and Soft X-Ray Regions (open access)

Laboratory Calibration of Density-Dependent Lines in the EUV and Soft X-Ray Regions

We analyzed spectral data of Fe XXII and Ar XIV from laboratory sources in which the electron density varies by several orders of magnitude to help benchmark density-sensitive emission lines useful for astrophysics and to test the atomic models underlying the diagnostic line ratios. We found excellent agreement for Fe XXII, but poorer agreement for Ar XIV. A number of astrophysically important emission lines are sensitive to electron density in the EUV and soft X-ray regions. Lines from Fe XXII, for example, have been used in recent years as diagnostics of stellar coronae, such as the active variable AB Dor, Capella, and EX Hya (Sanz-Forcada et al. 2003, Mewe et al. 2001, Mauche et al. 2003). Here we report spectral data of Fe XXII and Ar XIV from laboratory sources in which the electron density is known from either K-shell density diagnostics (for electron beam ion traps) or from non-spectroscopic means (tokamaks), ranging from 5 x 10{sup 10} cm{sup -3} to 5 x 10{sup 14} cm{sup -3}. These measurements were used to test the atomic data underlying the density diagnostic line ratios, complementing earlier work (Chen et al. 2004).
Date: December 9, 2010
Creator: Lepson, J K; Beiersdorfer, P; Gu, M F & Desai, P
System: The UNT Digital Library
Improved Characterization of Transmitted Wavefront Error on CADB Epoxy-Free Bonded Solid State Laser Materials (open access)

Improved Characterization of Transmitted Wavefront Error on CADB Epoxy-Free Bonded Solid State Laser Materials

Current state-of-the-art and next generation laser systems - such as those used in the NIF and LIFE experiments at LLNL - depend on ever larger optical elements. The need for wide aperture optics that are tolerant of high power has placed many demands on material growers for such diverse materials as crystalline sapphire, quartz, and laser host materials. For such materials, it is either prohibitively expensive or even physically impossible to fabricate monolithic pieces with the required size. In these cases, it is preferable to optically bond two or more elements together with a technique such as Chemically Activated Direct Bonding (CADB{copyright}). CADB is an epoxy-free bonding method that produces bulk-strength bonded samples with negligible optical loss and excellent environmental robustness. The authors have demonstrated CADB for a variety of different laser glasses and crystals. For this project, they will bond quartz samples together to determine the suitability of the resulting assemblies for large aperture high power laser optics. The assemblies will be evaluated in terms of their transmitted wavefront error, and other optical properties.
Date: December 9, 2010
Creator: Bayramian, A.
System: The UNT Digital Library
Time-Integrated Searches for Point-like Sources of Neutrinos with the 40-String IceCube Detector (open access)

Time-Integrated Searches for Point-like Sources of Neutrinos with the 40-String IceCube Detector

None
Date: December 9, 2010
Creator: IceCube & etal, Abbasi, R,
System: The UNT Digital Library
Deciphering the Electron Transport Pathway for Graphene Oxide Reduction by Shewanella oneidensis MR-1 (open access)

Deciphering the Electron Transport Pathway for Graphene Oxide Reduction by Shewanella oneidensis MR-1

None
Date: December 9, 2010
Creator: Jiao, Y.; Qian, F.; Li, Y.; Wang, G. M.; Saltikov, C. & Granick, J.
System: The UNT Digital Library