A 10-Hz Terawatt Class Ti:Sapphire Laser System: Development and Applications (open access)

A 10-Hz Terawatt Class Ti:Sapphire Laser System: Development and Applications

We developed a two stage Ti:Sapphire laser system to generate 16 mJ/80fs laser pulses at the pulse repetition rate of 10 Hz. The key deriver for the present design is implementing a highly efficient symmetric confocal pre-amplifier and employing a simple, inexpensive synchronization scheme relying only on a commercial digital delay-generator. We characterized the amplified pulses in spatial-, spectral-, and temporal-domains. The laser system was used to investigate various nonlinear optical processes, and to modify the optical properties of metal- and semiconductor-surfaces. We are currently building a third amplifier to boost the laser power to the multi-terawatt range.
Date: January 12, 2010
Creator: Sharma, A. K.; Smedley, J.; Tsang, T. & Rao, T.
Object Type: Article
System: The UNT Digital Library
500 MW X-BAND RF SYSTEM OF A 0.25 GEV ELECTRON LINAC FOR ADVANCED COMPTON SCATTERING SOURCE APPLICATION (open access)

500 MW X-BAND RF SYSTEM OF A 0.25 GEV ELECTRON LINAC FOR ADVANCED COMPTON SCATTERING SOURCE APPLICATION

A Mono-Energetic Gamma-Ray (MEGa-Ray) Compton scattering light source is being developed at LLNL in collaboration with SLAC National Accelerator Laboratory. The electron beam for the Compton scattering interaction will be generated by a X-band RF gun and a X-band LINAC at the frequency of 11.424 GHz. High power RF in excess of 500 MW is needed to accelerate the electrons to energy of 250 MeV or greater for the interaction. Two high power klystron amplifiers, each capable of generating 50 MW, 1.5 msec pulses, will be the main high power RF sources for the system. These klystrons will be powered by state of the art solid-state high voltage modulators. A RF pulse compressor, similar to the SLED II pulse compressor, will compress the klystron output pulse with a power gain factor of five. For compactness consideration, we are looking at a folded waveguide setup. This will give us 500 MW at output of the compressor. The compressed pulse will then be distributed to the RF gun and to six traveling wave accelerator sections. Phase and amplitude control are located at the RF gun input and additional control points along the LINAC to allow for parameter control during operation. This high …
Date: May 12, 2010
Creator: Chu, T S; Anderson, S G; Gibson, D J; Hartemann, F V; Marsh, R A; Siders, C et al.
Object Type: Article
System: The UNT Digital Library
2009 Release of the Evaluated Nuclear Data Library (ENDL2009) (open access)

2009 Release of the Evaluated Nuclear Data Library (ENDL2009)

None
Date: August 12, 2010
Creator: Beck, B.; Brown, D. A.; Descalle, M. A.; Hagmann, C.; Hoffman, R.; Ormand, E. et al.
Object Type: Report
System: The UNT Digital Library
Actinic imaging of native and programmed defects on a full-field mask (open access)

Actinic imaging of native and programmed defects on a full-field mask

We describe the imaging and characterization of native defects on a full field extreme ultraviolet (EUV) mask, using several reticle and wafer inspection modes. Mask defect images recorded with the SEMA TECH Berkeley Actinic Inspection Tool (AIT), an EUV-wavelength (13.4 nm) actinic microscope, are compared with mask and printed-wafer images collected with scanning electron microscopy (SEM) and deep ultraviolet (DUV) inspection tools. We observed that defects that appear to be opaque in the SEM can be highly transparent to EUV light, and inversely, defects that are mostly transparent to the SEM can be highly opaque to EUV. The nature and composition of these defects, whether they appear on the top surface, within the multilayer coating, or on the substrate as buried bumps or pits, influences both their significance when printed, and their detectability with the available techniques. Actinic inspection quantitatively predicts the characteristics of printed defect images in ways that may not be possible with non-EUV techniques. As a quantitative example, we investigate the main structural characteristics of a buried pit defect based on EUV through-focus imaging.
Date: March 12, 2010
Creator: Mochi, I.; Goldberg, K. A.; Fontaine, B. La; Tchikoulaeva, A. & Holfeld, C.
Object Type: Article
System: The UNT Digital Library
ADVANCED X-BAND TEST ACCELERATOR FOR HIGH BRIGHTNESS ELECTRON AND GAMMA RAY BEAMS (open access)

ADVANCED X-BAND TEST ACCELERATOR FOR HIGH BRIGHTNESS ELECTRON AND GAMMA RAY BEAMS

In support of Compton scattering gamma-ray source efforts at LLNL, a multi-bunch test stand is being developed to investigate accelerator optimization for future upgrades. This test stand will enable work to explore the science and technology paths required to boost the current 10 Hz monoenergetic gamma-ray (MEGa-Ray) technology to an effective repetition rate exceeding 1 kHz, potentially increasing the average gamma-ray brightness by two orders of magnitude. Multiple bunches must be of exceedingly high quality to produce narrow-bandwidth gamma-rays. Modeling efforts will be presented, along with plans for a multi-bunch test stand at LLNL. The test stand will consist of a 5.5 cell X-band rf photoinjector, single accelerator section, and beam diagnostics. The photoinjector will be a high gradient standing wave structure, featuring a dual feed racetrack coupler. The accelerator will increase the electron energy so that the emittance can be measured using quadrupole scanning techniques. Multi-bunch diagnostics will be developed so that the beam quality can be measured and compared with theory. Design will be presented with modeling simulations, and layout plans.
Date: May 12, 2010
Creator: Marsh, R A; Anderson, S G; Barty, C P; Chu, T S; Ebbers, C A; Gibson, D J et al.
Object Type: Article
System: The UNT Digital Library
Aerosol indirect effects ? general circulation model intercomparison and evaluation with satellite data (open access)

Aerosol indirect effects ? general circulation model intercomparison and evaluation with satellite data

Aerosol indirect effects continue to constitute one of the most important uncertainties for anthropogenic climate perturbations. Within the international AEROCOM initiative, the representation of aerosol-cloud-radiation interactions in ten different general circulation models (GCMs) is evaluated using three satellite datasets. The focus is on stratiform liquid water clouds since most GCMs do not include ice nucleation effects, and none of the model explicitly parameterises aerosol effects on convective clouds. We compute statistical relationships between aerosol optical depth ({tau}{sub a}) and various cloud and radiation quantities in a manner that is consistent between the models and the satellite data. It is found that the model-simulated influence of aerosols on cloud droplet number concentration (N{sub d}) compares relatively well to the satellite data at least over the ocean. The relationship between {tau}{sub a} and liquid water path is simulated much too strongly by the models. This suggests that the implementation of the second aerosol indirect effect mainly in terms of an autoconversion parameterisation has to be revisited in the GCMs. A positive relationship between total cloud fraction (f{sub cld}) and {tau}{sub a} as found in the satellite data is simulated by the majority of the models, albeit less strongly than that in the …
Date: March 12, 2010
Creator: Quaas, Johannes; Ming, Yi; Menon, Surabi; Takemura, Toshihiko; Wang, Minghuai; Penner, Joyce E. et al.
Object Type: Article
System: The UNT Digital Library
Afghanistan Casualties: Military Forces and Civilians (open access)

Afghanistan Casualties: Military Forces and Civilians

This report collects statistics from a variety of sources on casualties sustained during Operation Enduring Freedom (OEF), which began on October 7, 2001. OEF actions took place primarily in Afghanistan; however, OEF casualties also includes American casualties in Pakistan, Uzbekistan, Guantanamo Bay (Cuba), Djibouti, Eritrea, Ethiopia, Jordan, Kenya, Kyrgyzstan, the Philippines, Seychelles, Sudan, Tajikistan, Turkey, and Yemen.
Date: April 12, 2010
Creator: Chesser, Susan G.
Object Type: Report
System: The UNT Digital Library
Afghanistan Casualties: Military Forces and Civilians (open access)

Afghanistan Casualties: Military Forces and Civilians

This report collects statistics from a variety of sources on casualties sustained during Operation Enduring Freedom (OEF), which began on October 7, 2001. OEF actions took place primarily in Afghanistan; however, OEF casualties also includes American casualties in Pakistan, Uzbekistan, Guantanamo Bay (Cuba), Djibouti, Eritrea, Ethiopia, Jordan, Kenya, Kyrgyzstan, the Philippines, Seychelles, Sudan, Tajikistan, Turkey, and Yemen.
Date: July 12, 2010
Creator: Chesser, Susan G.
Object Type: Report
System: The UNT Digital Library
Afghanistan: Politics, Elections, and Government Performance (open access)

Afghanistan: Politics, Elections, and Government Performance

This report discusses the current political state of Afghanistan, as well as the Afghan government. This report also discusses Afghanistan's relationship with the United States, particularly U.S. efforts to urge President Hamid Karzai, to address corruption within the Afghan government. The report also includes discussion of election fraud and corruption in Afghanistan.
Date: November 12, 2010
Creator: Katzman, Kenneth
Object Type: Report
System: The UNT Digital Library
Afghanistan: U.S. Foreign Assistance (open access)

Afghanistan: U.S. Foreign Assistance

The U.S. program of assistance to Afghanistan is intended to stabilize and strengthen the Afghan economic, social, political, and security environment so as to blunt popular support for extremist forces in the region. Since 2001, nearly $52 billion has been appropriated toward this effort. This report provides a "big picture" overview of the U.S. aid program and congressional action. It describes what various aid agencies report they are doing in Afghanistan. It does not address the effectiveness of their programs.
Date: August 12, 2010
Creator: Tarnoff, Curt
Object Type: Report
System: The UNT Digital Library
Air Force KC-X Tanker Aircraft Program: Background and Issues for Congress (open access)

Air Force KC-X Tanker Aircraft Program: Background and Issues for Congress

This report discusses issues for Congress in FY2011, which are whether to approve, reject, or modify DOD's new KC-X competition strategy, and whether to approve, reject, or modify the Air Force's request for FY2011 research and development funding for the new KC-X program.
Date: March 12, 2010
Creator: Gertler, Jeremiah
Object Type: Report
System: The UNT Digital Library
ALLOYING-DRIVEN PHASE STABILITY IN GROUP VB TRANSITION METALS UNDER COMPRESSION (open access)

ALLOYING-DRIVEN PHASE STABILITY IN GROUP VB TRANSITION METALS UNDER COMPRESSION

None
Date: July 12, 2010
Creator: Landa, A.; Soderlind, P.; Velikokhatnyi, O. I.; Naumov, I. I.; Ruban, A. V.; Peil, O. E. et al.
Object Type: Article
System: The UNT Digital Library
Alphabet Soup - An Overview of Diagnostic Techniques (open access)

Alphabet Soup - An Overview of Diagnostic Techniques

This report gives an overview of diagnostic techniques of "Alphabet Soup".
Date: October 12, 2010
Creator: Smedley, J.
Object Type: Article
System: The UNT Digital Library
Applications of Laser and Synchrotron Based ARPES to Photocathode Research (open access)

Applications of Laser and Synchrotron Based ARPES to Photocathode Research

Laser angle resolved photoelectron spectroscopy (ARPES) provides unique information about angle and energy distribution of photoelectrons. Laser ARPES gives unique insight into how NEA materials work. ARPES combined with some ancillary measurements gives a very complete picture of system electronic physics. For H:C[100] there is now a clear program for engineering as well as development analogous systems. ARPES well suited for identifying 'ideal' photocathodes with intrinsically low emittance and high QE.
Date: October 12, 2010
Creator: Rameau, J.; Smedley. J.; Muller, E.; Kidd, T.; Johnson, P.; Allen, P. et al.
Object Type: Article
System: The UNT Digital Library
The April 2010 Coup in Kyrgyzstan: Context and Implications for U.S. Interests (open access)

The April 2010 Coup in Kyrgyzstan: Context and Implications for U.S. Interests

This report discusses the coup and its aftermath in Kyrgyzstan, and its implications for Kyrgyzstan, U.S. interests, Russia and other Euroasian states.
Date: April 12, 2010
Creator: Nichol, Jim
Object Type: Report
System: The UNT Digital Library
Assessing Potential Impacts of Stannous Chloride Based Mercury Treatment on a Receiving Stream Using Real-World Data From Tims Branch, Savannah River Site (open access)

Assessing Potential Impacts of Stannous Chloride Based Mercury Treatment on a Receiving Stream Using Real-World Data From Tims Branch, Savannah River Site

As part of the efforts to develop and implement a comprehensive mercury mitigation strategy for Oak Ridge, the Department of Energy (DOE) is considering deployment of a stannous chloride based treatment technology to decrease the releases of mercury to East Fork Poplar Creek.
Date: July 12, 2010
Creator: Looney, B.; Jackson, D.; Peterson, M.; Mathews, T.; Southworth, G.; Paller, M. et al.
Object Type: Report
System: The UNT Digital Library
Atmospheric Effects on the Performance of Cdznte Single Crystal Detectors (open access)

Atmospheric Effects on the Performance of Cdznte Single Crystal Detectors

The production of high-quality ternary single-crystal materials for radiation detectors has progressed over the past 15 years. One of the more common materials being studied is CdZnTe (CZT), which can be grown using several methods to produce detector-grade materials. The work presented herein examines the effects of environmental conditions including temperature and humidity on detector performance [full-width at half-maximum (FWHM)] using the single pixel with guard detector configuration. The effects of electrical probe placement, reproducibility, and aging are also presented.
Date: May 12, 2010
Creator: Washington, A.; Duff, M. & Teague, L.
Object Type: Article
System: The UNT Digital Library
Atmospheric Radiation Measurement Program Climate Research Facility Operations Quarterly Report. October 1 - December 31, 2009. (open access)

Atmospheric Radiation Measurement Program Climate Research Facility Operations Quarterly Report. October 1 - December 31, 2009.

Individual raw data streams from instrumentation at the Atmospheric Radiation Measurement (ARM) Program Climate Research Facility (ACRF) fixed and mobile sites are collected and sent to the Data Management Facility (DMF) at Pacific Northwest National Laboratory (PNNL) for processing in near real-time. Raw and processed data are then sent approximately daily to the ACRF Archive, where they are made available to users. For each instrument, we calculate the ratio of the actual number of data records received daily at the Archive to the expected number of data records. The results are tabulated by (1) individual data stream, site, and month for the current year and (2) site and fiscal year (FY) dating back to 1998. The U.S. Department of Energy (DOE) requires national user facilities to report time-based operating data. The requirements concern the actual hours of operation (ACTUAL); the estimated maximum operation or uptime goal (OPSMAX), which accounts for planned downtime; and the VARIANCE [1 - (ACTUAL/OPSMAX)], which accounts for unplanned downtime. The OPSMAX time for the first quarter of FY 2010 for the North Slope Alaska (NSA) locale is 1,987.20 hours (0.90 x 2,208); for the Southern Great Plains (SGP) site is 2,097.60 hours (0.95 x 2,208); and …
Date: January 12, 2010
Creator: Sisterson, D. L.
Object Type: Report
System: The UNT Digital Library
Batteries: Overview of Battery Cathodes (open access)

Batteries: Overview of Battery Cathodes

The very high theoretical capacity of lithium (3829 mAh/g) provided a compelling rationale from the 1970's onward for development of rechargeable batteries employing the elemental metal as an anode. The realization that some transition metal compounds undergo reductive lithium intercalation reactions reversibly allowed use of these materials as cathodes in these devices, most notably, TiS{sub 2}. Another intercalation compound, LiCoO{sub 2}, was described shortly thereafter but, because it was produced in the discharged state, was not considered to be of interest by battery companies at the time. Due to difficulties with the rechargeability of lithium and related safety concerns, however, alternative anodes were sought. The graphite intercalation compound (GIC) LiC{sub 6} was considered an attractive candidate but the high reactivity with commonly used electrolytic solutions containing organic solvents was recognized as a significant impediment to its use. The development of electrolytes that allowed the formation of a solid electrolyte interface (SEI) on surfaces of the carbon particles was a breakthrough that enabled commercialization of Li-ion batteries. In 1990, Sony announced the first commercial batteries based on a dual Li ion intercalation system. These devices are assembled in the discharged state, so that it is convenient to employ a prelithiated cathode …
Date: July 12, 2010
Creator: Doeff, Marca M
Object Type: Book
System: The UNT Digital Library
Beam commissioning results for the RFQ and MEBT of the EBIS based preinjector for RHIC (open access)

Beam commissioning results for the RFQ and MEBT of the EBIS based preinjector for RHIC

The EBIS based preinjector for both the Relativistic Heavy Ion Collider (RHIC) and NASA Space Radiation Laboratory (NSRL) is now being commissioned at Brookhaven National Laboratory (BNL). In 2008, the RFQ for the project was delivered and commissioned using Test EBIS, which was built to demonstrate the high current EBIS's performance. A dedicated beamline after the RFQ was assembled to confirm the RFQ's performance, and the beam energy was measured by a bending dipole magnet. In November 2009, the RFQ was moved to the final location and the vanes were realigned. The beam commissioning with the RHIC-EBIS was started again during March 2010. The RFQ accelerates ions from 17 keV/u to 300 keV/u and operates at 100.625 MHz. It is followed by a short Medium Energy Beam Transport (MEBT), which consists of four quadrupoles and one buncher cavity. Some temporary diagnostics for this commissioning include an emittance probe, TOF system, fast Faraday cup, and beam current measurement units. As of September 2010, the RFQ and the MEBT show expected performance with He{sup +}, Au{sup 32+} and Fe{sup 20+} beams. Further commissioning for higher intensity beams is in progress.
Date: September 12, 2010
Creator: Okamura, M.; Alessi, J.; Beebe, E.; Kondo, K.; Lambiase, R.; Lockey, R. et al.
Object Type: Article
System: The UNT Digital Library
Birthright Citizenship Under the 14th Amendment of Persons Born in the United States to Alien Parents (open access)

Birthright Citizenship Under the 14th Amendment of Persons Born in the United States to Alien Parents

This report provides background information on birthright citizenship to alien parents in the U.S. The report ends with a detail of amendments in the 112th Congress that would amend the Constitution to exclude from citizenship at birth persons born in the United States whose parents are unlawfully present in the United States or are non-immigrant aliens.
Date: August 12, 2010
Creator: Lee, Margaret Mikyung
Object Type: Report
System: The UNT Digital Library
Bosnia: Current Issues and U.S. Policy (open access)

Bosnia: Current Issues and U.S. Policy

This report presents an overview of the economic and political situation in Bosnia. It starts out by describing the current situation, the negotiations on forming a new central government, the international role in Bosnia, and the last part discusses the implications of U.S. policy.
Date: April 12, 2010
Creator: Woehrel, Steven
Object Type: Report
System: The UNT Digital Library
Broadband Internet Access and the Digital Divide: Federal Assistance Programs (open access)

Broadband Internet Access and the Digital Divide: Federal Assistance Programs

This report provides information about the Broadband Internet Access and the Digital Divide through Federal Assistance Programs.
Date: January 12, 2010
Creator: Kruger, Lennard G. & Gilroy, Angele A.
Object Type: Report
System: The UNT Digital Library
Budget Enforcement Procedures: Senate Pay- As-You-Go (PAYGO) Rule (open access)

Budget Enforcement Procedures: Senate Pay- As-You-Go (PAYGO) Rule

This report discusses the Senate pay-as-you-go, or PAYGO, rule which generally requires that any legislation projected to increase direct spending or reduce revenues must also include equivalent amounts of direct spending cuts, revenue increases, or a combination of the two, so that the legislation does not increase the on-budget deficit over a six-year period and an 11-year period.
Date: January 12, 2010
Creator: Heniff, Bill, Jr.
Object Type: Report
System: The UNT Digital Library