Thick beryllium coatings by magnetron sputtering (open access)

Thick beryllium coatings by magnetron sputtering

Thick (>150 {micro}m) beryllium coatings are studied as an ablator material of interest for fusion fuel capsules for the National Ignition Facility (NIF). As an added complication, the coatings are deposited on mm-scale spherical substrates, as opposed to flats. DC magnetron sputtering is used because of the relative controllability of the processing temperature and energy of the deposits. We used ultra small angle x-ray spectroscopy (USAXS) to characterize the void fraction and distribution along the spherical surface. We investigated the void structure using a combination focused ion beam (FIB) and scanning electron microscope (SEM), along with transmission electron microscopy (TEM). Our results show a few volume percent of voids and a typical void diameter of less than two hundred nanometers. Understanding how the stresses in the deposited material develop with thickness is important so that we can minimize film cracking and delamination. To that end, an in-situ multiple optical beam stress sensor (MOSS) was used to measure the stress behavior of thick Beryllium coatings on flat substrates as the material was being deposited. We will show how the film stress saturates with thickness and changes with pressure.
Date: April 14, 2011
Creator: Wu, H.; Nikroo, A.; Youngblood, K.; Moreno, K.; Wu, D.; Fuller, T. et al.
System: The UNT Digital Library
Search for the Rare Decay B -> K nu nubar (open access)

Search for the Rare Decay B -> K nu nubar

We present a search for the rare decays B{sup +} {yields} K{sup +}{nu}{bar {nu}} and B{sup 0} {yields} K{sup 0}{nu}{bar {nu}} using 459 million B{bar B} pairs collected with the BABAR detector at the SLAC National Accelerator Laboratory. Flavor-changing neutral-current decays such as these are forbidden at tree level but can occur through one-loop diagrams in the Standard Model (SM), with possible contributions from new physics at the same order. The presence of two neutrinos in the final state makes identification of signal events challenging, so reconstruction in the semileptonic decay channels B {yields} D{sup (*)}l{nu} of the B meson recoiling from the signal B is used to suppress backgrounds. We set an upper limit at the 90% confidence level of 1.3 x 10{sup -5} on the total branching fraction for B{sup +} {yields} K{sup +}{nu}{bar {nu}}, and 5.6 x 10{sup -5} for B{sup 0} {yields} K{sup 0}{nu}{bar {nu}}. We additionally report partial branching fractions in two ranges of di-neutrino mass squared for B{sup +} {yields} K{sup +}{nu}{bar {nu}}.
Date: September 14, 2010
Creator: del Amo Sanchez, P.; Lees, J.P.; Poireau, V.; Prencipe, E.; Tisserand, V.; Garra Tico, J. et al.
System: The UNT Digital Library
Performace of Multi-Probe Corrosion Monitoring Systems at the Hanford Site (open access)

Performace of Multi-Probe Corrosion Monitoring Systems at the Hanford Site

Between 2007 and 2009, several different multi-probe corrosion monitoring systems were designed and installed in high-level nuclear waste tanks at the U.S. Department of Energy's Hanford Site in WaShington State. The probe systems are being monitored to ensure waste tanks operate in regions that minimize localized corrosion (i.e., pitting) and stress corrosion cracking. The corrosion monitoring systems have been installed in wastes with different chemistry types. An ongoing effort during the same time period has generated non-radioactive simulants that are tested in the laboratory to establish baseline corrosion monitoring system performance and characterize data to allow interpretation of readings from the multiple corrosion monitoring systems. Data collection from these monitoring systems has reached the point where the results allow comparison with the laboratory testing. This paper presents analytical results from the corrosion monitoring system development program.
Date: January 14, 2010
Creator: Carothers, K. D.; Boomer, K. D.; Anda, V. S.; Dahl, M. M. & Edgemon, G. L.
System: The UNT Digital Library
Development of Readout Interconnections for the Si-W Calorimeter of SiD (open access)

Development of Readout Interconnections for the Si-W Calorimeter of SiD

The SiD collaboration is developing a Si-W sampling electromagnetic calorimeter, with anticipated application for the International Linear Collider. Assembling the modules for such a detector will involve special bonding technologies for the interconnections, especially for attaching a silicon detector wafer to a flex cable readout bus. We review the interconnect technologies involved, including oxidation removal processes, pad surface preparation, solder ball selection and placement, and bond quality assurance. Our results show that solder ball bonding is a promising technique for the Si-W ECAL, and unresolved issues are being addressed.
Date: September 14, 2012
Creator: Woods, M.; Fields, R. G.; Holbrook, B.; Lander, R. L.; Moskaleva, A.; Neher, C. et al.
System: The UNT Digital Library
Interferometric adaptive optics for the National Ignition Facility (open access)

Interferometric adaptive optics for the National Ignition Facility

None
Date: January 14, 2010
Creator: Baker, K.; Homoelle, D.; Stappaerts, E.; Siders, C. & Barty, C.
System: The UNT Digital Library
The E166 experiment: Development of an Undulator-Based Polarized Positron Source for the International Linear Collider (open access)

The E166 experiment: Development of an Undulator-Based Polarized Positron Source for the International Linear Collider

A longitudinal polarized positron beam is foreseen for the international linear collider (ILC). A proof-of-principle experiment has been performed in the final focus test beam at SLAC to demonstrate the production of polarized positrons for implementation at the ILC. The E166 experiment uses a 1 m long helical undulator in a 46.6 GeV electron beam to produce a few MeV photons with a high degree of circular polarization. These photons are then converted in a thin target to generate longitudinally polarized e{sup +} and e{sup -}. The positron polarization is measured using a Compton transmission polarimeter. The data analysis has shown asymmetries in the expected vicinity of 3.4% and {approx}1% for photons and positrons respectively and the expected positron longitudinal polarization is covering a range from 50% to 90%. The full exploitation of the physics potential of an international linear collider (ILC) will require the development of polarized positron beams. Having both e{sup +} and e{sup -} beams polarized will provide new insight into structures of couplings and thus give access to physics beyond the standard model [1]. The concept for a polarized positron source is based on circularly polarized photon sources. These photons are then converted to longitudinally polarized …
Date: November 14, 2011
Creator: Kovermann, J.; Stahl, A.; Mikhailichenko, A. A.; Scott, D.; Moortgat-Pick, G. A.; Gharibyan, V. et al.
System: The UNT Digital Library
PILOT-SCALE FIELD VALIDATION OF THE LONG ELECTRODE ELECTRICAL RESISTIVITY TOMOGRAPHY METHOD (open access)

PILOT-SCALE FIELD VALIDATION OF THE LONG ELECTRODE ELECTRICAL RESISTIVITY TOMOGRAPHY METHOD

Field validation for the long electrode electrical resistivity tomography (LE-ERT) method was attempted in order to demonstrate the performance of the technique in imaging a simple buried target. The experiment was an approximately 1/17 scale mock-up of a region encompassing a buried nuclear waste tank on the Hanford site. The target of focus was constructed by manually forming a simulated plume within the vadose zone using a tank waste simulant. The LE-ERT results were compared to ERT using conventional point electrodes on the surface and buried within the survey domain. Using a pole-pole array, both point and long electrode imaging techniques identified the lateral extents of the pre-formed plume with reasonable fidelity, but the LE-ERT was handicapped in reconstructing the vertical boundaries. The pole-dipole and dipole-dipole arrays were also tested with the LE-ERT method and were shown to have the least favorable target properties, including the position of the reconstructed plume relative to the known plume and the intensity of false positive targets. The poor performance of the pole-dipole and dipole-dipole arrays was attributed to an inexhaustive and non-optimal coverage of data at key electrodes, as well as an increased noise for electrode combinations with high geometric factors. However, when …
Date: July 14, 2011
Creator: Rucker, D. F.; Loke, M. H.; Crook, N. & Glaser, D. R.
System: The UNT Digital Library
Verification for Portability, Scalability, and Grokkability (open access)

Verification for Portability, Scalability, and Grokkability

None
Date: July 14, 2010
Creator: Humphrey, Alan; Derrick, Christopher; Tibbitts, Beth; Vo, Anh; Vakkalanka, Sarvani; Gopalakrishnan, Ganesh et al.
System: The UNT Digital Library
Molecular Dynamics Simulations of Classical Stopping Power (open access)

Molecular Dynamics Simulations of Classical Stopping Power

None
Date: August 14, 2013
Creator: Grabowski, Paul E.; Surh, Michael P.; Richards, David F.; Langdon, A. Bruce; Graziani, Frank R. & Murillo, Michael S.
System: The UNT Digital Library
Investigating Chemical and Molecular Changes in Uranium Oxyfluoride Particles using NanoSIMS and Micro-Raman Spectroscopy (open access)

Investigating Chemical and Molecular Changes in Uranium Oxyfluoride Particles using NanoSIMS and Micro-Raman Spectroscopy

None
Date: September 14, 2010
Creator: Kips, R.; Kristo, M. J.; Crowhurst, J.; Hutcheon, I. D.; Stefaniak, E. A. & Aregbe, Y.
System: The UNT Digital Library
MANAGING ENGINEERING ACTIVITIES FOR THE PLATEAU REMEDIATION CONTRACT - HANFORD (open access)

MANAGING ENGINEERING ACTIVITIES FOR THE PLATEAU REMEDIATION CONTRACT - HANFORD

In 2008, the primary Hanford clean-up contract transitioned to the CH2MHill Plateau Remediation Company (CHPRC). Prior to transition, Engineering resources assigned to remediation/Decontamination and Decommissioning (D&D) activities were a part of a centralized engineering organization and matrixed to the performing projects. Following transition, these resources were reassigned directly to the performing project, with a loose matrix through a smaller Central Engineering (CE) organization. The smaller (10 FTE) central organization has retained responsibility for the overall technical quality of engineering for the CHPRC, but no longer performs staffing and personnel functions. As the organization has matured, there are lessons learned that can be shared with other organizations going through or contemplating performing a similar change. Benefits that have been seen from the CHPRC CE organization structure include the following: (1) Staff are closely aligned with the 'Project/facility' that they are assigned to support; (2) Engineering priorities are managed to be consistent with the 'Project/facility' priorities; (3) Individual Engineering managers are accountable for identifying staffing needs and the filling of staffing positions; (4) Budget priorities are managed within the local organization structure; (5) Rather than being considered a 'functional' organization, engineering is considered a part of a line, direct funded organization; (6) …
Date: January 14, 2011
Creator: Kronvall, C. M.
System: The UNT Digital Library
Quantitative Analysis of Clustered DNA Damages Induced by Silicon Beams of Different Kinetic Energy (open access)

Quantitative Analysis of Clustered DNA Damages Induced by Silicon Beams of Different Kinetic Energy

Humans may b exposed to highly energetic charged particle radiation as a result of medical treatments, occupational activitie or accidental events. In recent years, our increasing presence and burgeoning interest in space exploration beyond low Earth orbit has led to a large increase in the research of the biological effects ofcharged particle radiation typical of that encountered in the space radiation environment. The study of the effects of these types of radiation qualities in terms ofDNA damage induction and repair is fundamental to understand mechanisms both underlying their greater biological effectiveness as we)) as the short and long term risks of health effects such as carcinogenesis, degen rative diseases and premature aging. Charged particle radiation induces a variety of DNA alterations, notably bistranded clustered damages, defined as two or more closely-opposed strand break , oxidized bases or abasic sites within a few helical turns. The induction of such highly complex DNA damage enhances the probability of incorrect or incomplete repair and thus constitutes greater potential for genomic instability, cell death and transformation.
Date: May 14, 2013
Creator: Keszenman, D. J.; Bennett, P. V.; Sutherland, B. M. & Wilson, P. F.
System: The UNT Digital Library
Characteristics of Undoped and Europium-doped SrI2 Scintillator Detectors (open access)

Characteristics of Undoped and Europium-doped SrI2 Scintillator Detectors

None
Date: November 14, 2011
Creator: Sturm, Benjamin W.; Cherepy, Nerine J.; Drury, Owen B.; Thelin, Peter A.; Fisher, Scott E.; Payne, Stephen A. et al.
System: The UNT Digital Library