An 8-Element Fast-Neutron Double-Scatter Directional Detector. (open access)

An 8-Element Fast-Neutron Double-Scatter Directional Detector.

We have constructed a fast-neutron double-scatter spectrometer that efficiently measures the neutron spectrum and direction of a spontaneous fission source. The device consists of two planes of organic scintillators, each having an area of 125 cm{sup 2}, efficiently coupled to photomultipliers. The four scintillators in the front plane are 2 cm thick, giving almost 25% probability of detecting an incident fission-spectrum neutron at 2 MeV by proton recoil and subsequent ionization. The back plane contains four 5-cm-thick scintillators which give a 40% probability of detecting a scattered fast neutron. A recordable double-scatter event occurs when a neutron is detected in both a front plane detector and a back plane detector within an interval of 500 nanoseconds. Each double-scatter event is analyzed to determine the energy deposited in the front plane, the time of flight between detectors, and the energy deposited in the back plane. The scattering angle of each incident neutron is calculated from the ratio of the energy deposited in the first detector to the kinetic energy of the scattered neutron.
Date: July 31, 2005
Creator: Vanier, P. E. & Forman, L.
System: The UNT Digital Library
Multiple Functions Long Trace Profiler (LTP-MF) for National Synchrotron Radiation Laboratory of China. (open access)

Multiple Functions Long Trace Profiler (LTP-MF) for National Synchrotron Radiation Laboratory of China.

The Long Trace Profiler (LTP) is a useful optical metrology instrument for measuring the figure and slope error of cylindrical aspheres commonly used as synchrotron radiation (SR) optics. It is used extensively at a number of synchrotron radiation laboratories around the world. In order to improve SR beam line quality and resolution, the National Synchrotron Radiation Laboratory (NSRL) of China is developing a versatile LTP that can be used to measure both SR optics and more conventional ''normal'' optical surfaces. The optical metrology laboratories at Brookhaven National Laboratory (BNL) and NSRL are collaborating in developing a multiple functions LTP (LTP-MF). Characteristics of the LTP-MF are: a very compact and lightweight optical head, a large angular test range ({+-} 16 mad) and high accuracy. The LTP-MF can be used in various configurations: as a laboratory-based LTP, an in-situ LTP or penta-prism LTP, as an angle monitor, a portable LTP, and a small radius of curvature test instrument. The schematic design of the compact optical head and a new compact slide are introduced. Analysis of different measurements modes and systematic error correction methods are introduced.
Date: July 31, 2005
Creator: Qian, S.; Wang, Q.; Hong, Y. & Takacs, P.
System: The UNT Digital Library
New Results From Testing of Coplanar-Grid CdZnTe Detector. (open access)

New Results From Testing of Coplanar-Grid CdZnTe Detector.

New results from studies of coplanar-grid CdZnTe (CZT) detectors are presented. The coplanar-grid detectors, were investigated by using a highly collimated X-ray beam available at Brookhaven's National Synchrotron Light Source and by applying a pulse-shape analysis. The coplanar-grid detector operates as a single-carrier device. Despite the fact that its operational principle is well known and has been investigated by many groups in the past, we found some new details that may explain the performance limits of these types of devices. The experimental results have been confirmed by extensive computer modeling.
Date: July 31, 2005
Creator: Carini, G. A. & AL., ET
System: The UNT Digital Library
The Normal State Gap in Electron Doped Cuprates. (open access)

The Normal State Gap in Electron Doped Cuprates.

None
Date: July 31, 2005
Creator: Lobo, R. P. S. M.; Bontemps, N.; Zimmers, A.; Dagan, Y.; Greene, R. L.; Fournier, P. et al.
System: The UNT Digital Library
Performance Studies of CdZnTe Detector by Using a Pulse Shape Analysis. (open access)

Performance Studies of CdZnTe Detector by Using a Pulse Shape Analysis.

Pulse shape analysis is proved to be a powerful tool to characterize the performance of CdZnTe devices and understand their operating principles. It allows one to investigate the device configurations, electron transport properties, effects governing charge collection, electric-field distributions, signal charge formation, etc. This work describes an application of different techniques based on the pulse shape measurements to characterize pixel, coplanar-grid, and virtual Frisch-grid devices and understand the electronic properties of CZT material provided by different vendors. We report new results that may explain the performance limits of these devices.
Date: July 31, 2005
Creator: Bolotnikov, A.
System: The UNT Digital Library
Real-Time Stability and Profile Comparison Measurements Between Two Different LTPs. (open access)

Real-Time Stability and Profile Comparison Measurements Between Two Different LTPs.

The Long Trace Profiler (LTP) is a precise angle measurement instrument, with a sensitivity and accuracy that can be in the sub-micron radian range. LTP characteristics depend on the particular LTP system schematic design, and the quality of components and assembly. The conditions of temperature, alignment, and mirror support during the measurement process vary between different laboratories, which influences significantly the test repeatability and accuracy. In this paper we introduce a direct comparison method to test the same object at the same point in the same environment at the same time by using two LTPs, which significantly increases the reliability of the comparison. A compact, portable LTP (PTLTP), which can be carried to different laboratories around the world, is used for comparison testing. Stability Comparison experiments between the LTP II at the National Synchrotron Radiation Research Center (NSRRC), and the PTLTP of Brookhaven National Laboratory (BNL) reveal significant differences in performance between the instruments. The experiment is set up so that each optical head simultaneously records both its own sample probe beam and also the probe beam from the other optical head. The two probe beams are reflected from same point on the mirror. Tests show that the stability of …
Date: July 31, 2005
Creator: Qian, S. & Wang, D. J.
System: The UNT Digital Library
Rolling circle amplification of metazoan mitochondrialgenomes (open access)

Rolling circle amplification of metazoan mitochondrialgenomes

Here we report the successful use of rolling circle amplification (RCA) for the amplification of complete metazoan mt genomes to make a product that is amenable to high-throughput genome sequencing techniques. The benefits of RCA over PCR are many and with further development and refinement of RCA, the sequencing of organellar genomics will require far less time and effort than current long PCR approaches.
Date: July 31, 2005
Creator: Simison, W. Brian; Lindberg, D. R. & Boore, J. L.
System: The UNT Digital Library
Scaling of the Superfluid Density in High-Temperature Superconductors. (open access)

Scaling of the Superfluid Density in High-Temperature Superconductors.

None
Date: July 31, 2005
Creator: Homes, C.
System: The UNT Digital Library
Soft X-Ray Resonant Diffraction in Transition Metal Oxides. (open access)

Soft X-Ray Resonant Diffraction in Transition Metal Oxides.

None
Date: July 31, 2005
Creator: Thomas, K. J.; Grenier, S.; Hill, J. P.; Chou, F. C.; Tomioka, Y,; Tokura, Y. et al.
System: The UNT Digital Library
Einstein: His Impact on Accelerators; His Impact on theWorld (open access)

Einstein: His Impact on Accelerators; His Impact on theWorld

The impact of the work of Albert Einstein on accelerator physics is described. Because of the limit of time, and also because the audience knows the details, the impact is described in broad strokes. Nevertheless, it is seen how his work has affected many different aspects of accelerator physics. In the second half of the talk, Albert Einstein's impact on the world will be discussed; namely his work on world peace (including his role as a pacifist, in the atomic bomb, and in arms control) and his efforts as a humanitarian (including his efforts on social justice, anti-racism, and civil rights).
Date: July 30, 2005
Creator: Sessler, A.
System: The UNT Digital Library
Soft-x-ray spectroscopy study of nanoscale materials (open access)

Soft-x-ray spectroscopy study of nanoscale materials

The ability to control the particle size and morphology of nanoparticles is of crucial importance nowadays both from a fundamental and industrial point of view considering the tremendous amount of high-tech applications. Controlling the crystallographic structure and the arrangement of atoms along the surface of nanostructured material will determine most of its physical properties. In general, electronic structure ultimately determines the properties of matter. Soft X-ray spectroscopy has some basic features that are important to consider. X-ray is originating from an electronic transition between a localized core state and a valence state. As a core state is involved, elemental selectivity is obtained because the core levels of different elements are well separated in energy, meaning that the involvement of the inner level makes this probe localized to one specific atomic site around which the electronic structure is reflected as a partial density-of-states contribution. The participation of valence electrons gives the method chemical state sensitivity and further, the dipole nature of the transitions gives particular symmetry information. The new generation synchrotron radiation sources producing intensive tunable monochromatized soft X-ray beams have opened up new possibilities for soft X-ray spectroscopy. The introduction of selectively excited soft X-ray emission has opened a new …
Date: July 30, 2005
Creator: Guo, J.-H.
System: The UNT Digital Library
Challenges of Investigating Fluid-Elastic Lock-In of a Shallow Cavity and a Cantilevered Beam at Low Mach Numbers (open access)

Challenges of Investigating Fluid-Elastic Lock-In of a Shallow Cavity and a Cantilevered Beam at Low Mach Numbers

This report was prepared to talk about Challenges of Investigating Fluid-Elastic Lock-In of a Shallow Cavity and a Cantilevered Beam at Low Mach Numbers
Date: July 29, 2005
Creator: Cody, K Lai-Fook; Hambric, SA & Pollack, ML
System: The UNT Digital Library
Distributed Generation with Heat Recovery and Storage (open access)

Distributed Generation with Heat Recovery and Storage

Electricity generated by distributed energy resources (DER) located close to end-use loads has the potential to meet consumer requirements more efficiently than the existing centralized grid. Installation of DER allows consumers to circumvent the costs associated with transmission congestion and other non-energy costs of electricity delivery and potentially to take advantage of market opportunities to purchase energy when attractive. On-site thermal power generation is typically less efficient than central station generation, but by avoiding non-fuel costs of grid power and utilizing combined heat and power (CHP) applications, i.e., recovering heat from small-scale on-site generation to displace fuel purchases, then DER can become attractive to a strictly cost-minimizing consumer. In previous efforts, the decisions facing typical commercial consumers have been addressed using a mixed-integer linear programme, the DER Customer Adoption Model(DER-CAM). Given the site s energy loads, utility tariff structure, and information (both technical and financial) on candidate DER technologies, DER-CAM minimizes the overall energy cost for a test year by selecting the units to install and determining their hourly operating schedules. In this paper, the capabilities of DER-CAM are enhanced by the inclusion of the option to store recovered low-grade heat. By being able to keep an inventory of heat …
Date: July 29, 2005
Creator: Siddiqui, Afzal; Marnay, Chris; Firestone, Ryan M. & Zhou, Nan
System: The UNT Digital Library
Energetics of the N-O Bonds in 2-Hydroxyphenazine-di-N-oxide (open access)

Energetics of the N-O Bonds in 2-Hydroxyphenazine-di-N-oxide

Article on energetics of the N-O bonds in 2-hydroxyphenazine-di-N-oxide.
Date: July 29, 2005
Creator: Gomes, José R. B.; Sousa, Emanuel A.; Gonçalves, Jorge M.; Monte, Manuel J. S.; Gomes, Paula; Pandey, Siddharth et al.
System: The UNT Digital Library
Energy Technologies for the 21st Century-The Roles of Renewable Energy (open access)

Energy Technologies for the 21st Century-The Roles of Renewable Energy

Renewable energy sources, originating for the most part from the sun's radiant energy, are ubiquitous, long-lived, essentially free of carbon emissions, and have the potential to contribute significantly to mounting energy needs of the globe. In terms of percentage increase in installed capacity, renewable energy collectively is the fastest growing energy source. Even assuming that the developing world raises its standard of living considerably, the technical potential of renewable energies is more than enough to meet annual global needs several times over a century from now. Realizing even some of this potential involves overcoming obstacles in generation costs, proximity to markets, and in many cases intermittency, as well as others. From the perspective of work on a wide range of energy technologies by both the World Energy Council and the Intergovernmental Panel on Climate Change, the potential, timing, and investment costs for renewable energy technologies in the 21st century have become clearer. The marketplace, based on cost and performance, will determine which technologies are commercialized along with government policies that at a minimum do not hinder their introduction, and--at a maximum--may encourage more rapid and successful introduction. A wide range of possible scenarios (34) based on factors that include energy …
Date: July 29, 2005
Creator: Schock, R N
System: The UNT Digital Library
Experimental Investigation of the Structural Scattering Due to Impedance Discontinuities on a Cylindrical Shell (open access)

Experimental Investigation of the Structural Scattering Due to Impedance Discontinuities on a Cylindrical Shell

None
Date: July 29, 2005
Creator: Glotzbecker, RJ; Hambric, SA & Pollack, ML
System: The UNT Digital Library
Femtoscopy in Relativistic Heavy Ion Collisions (open access)

Femtoscopy in Relativistic Heavy Ion Collisions

Analyses of two-particle correlations have provided the chief means for determining spatio-temporal characteristics of relativistic heavy ion collisions. We discuss the theoretical formalism behind these studies and the experimental methods used in carrying them out. Recent results from RHIC are put into context in a systematic review of correlation measurements performed over the past two decades. The current understanding of these results are discussed in terms of model comparisons and overall trends.
Date: July 29, 2005
Creator: Lisa, M; Pratt, S; Soltz, R A & Wiedemann, U
System: The UNT Digital Library
Hybrid Bridgman Anvil Design: An Optical Window for in-Situ Spectroscopy in Large Volume Presses (open access)

Hybrid Bridgman Anvil Design: An Optical Window for in-Situ Spectroscopy in Large Volume Presses

The absence of in-situ optical probes for large volume presses often limits their application to high-pressure materials research. In this paper, we present a unique anvil/optical window-design for use in large volume presses, which consists of an inverted diamond anvil seated in a Bridgman type anvil. A small cylindrical aperture through the Bridgman anvil ending at the back of diamond anvil allows optical access to the sample chamber and permits direct optical spectroscopy measurements, such as ruby fluorescence (in-situ pressure) or Raman spectroscopy. This performance of this anvil-design has been demonstrated by loading KBr to a pressure of 14.5 GPa.
Date: July 29, 2005
Creator: Lipp, M. J.; Evans, W. J. & Yoo, C. S.
System: The UNT Digital Library
Measurements of Eavesdropping in a Wavelength/Time Optical CDMA (O-CDMA) System, with Data Confidentiality Implications (open access)

Measurements of Eavesdropping in a Wavelength/Time Optical CDMA (O-CDMA) System, with Data Confidentiality Implications

We report measurements on what an eavesdropper ''sees'' when tapping into a wavelength/time O-CDMA system in which 16 of 32 codes are ''lit''. Severe multi-access interference (MAI) provides some data confidentiality.
Date: July 29, 2005
Creator: Mendez, A. J.; Hernandez, V. J.; Bennett, C. V.; Gagliardi, R. M. & Lennon, W. J.
System: The UNT Digital Library
Advancements in time-resolved x-ray laser induced time-of-flight photoelectron spectroscopy (open access)

Advancements in time-resolved x-ray laser induced time-of-flight photoelectron spectroscopy

Time-resolved soft x-ray photoelectron spectroscopy is used to probe the non-steady-state evolution of the valence band electronic structure of laser heated ultra-thin (50 nm) metal foils and bulk semiconductors. Single-shot soft x-ray laser induced time-of-flight photoelectron spectroscopy with picosecond time resolution was used in combination with optical measurements of the disassembly dynamics that have shown the existence of a metastable liquid phase in fs-laser heated metal foils persisting 4-5 ps. This metastable phase is studied using a 527 nm wavelength 400 fs laser pulse containing 0.3-2.5 mJ laser energy focused in a large 500 x 700 {micro}m{sup 2} spot to create heated conditions of 0.2-1.8 x 10{sup 12} W cm{sup -2} intensity. The unique LLNL COMET compact tabletop soft x-ray laser source provided the necessary high photon flux, highly monoenergetic, picosecond pulse duration, and coherence for observing the evolution of changes in the valence band electronic structure of laser heated metals and semiconductors with picosecond time resolution. This work demonstrates the continuing development of a powerful new technique for probing reaction dynamics and changes of local order on surfaces on their fundamental timescales including phenomena such as non-thermal melting, chemical bond formation, intermediate reaction steps, and the existence of transient …
Date: July 28, 2005
Creator: Nelson, A J; Dunn, J; Widmann, K; Ao, T; Ping, Y; Hunter, J et al.
System: The UNT Digital Library
Diffraction grating eigenvector for translational and rotational motion (open access)

Diffraction grating eigenvector for translational and rotational motion

Future energy scaling of high-energy chirped-pulse amplification systems will benefit from the capability to coherently tile diffraction gratings into larger apertures. Design and operation of a novel, accurate alignment diagnostics for coherently tiled diffraction gratings is required for successful implementation of this technique. An invariant diffraction direction and phase for special moves of a diffraction grating is discussed, allowing simplification in the design of the coherently tiled grating diagnostics. An analytical proof of the existence of a unique diffraction grating eigenvector for translational and rotational motion which conserves the diffraction direction and diffracted wave phase is presented.
Date: July 28, 2005
Creator: Rushford, M C; Molander, W A; Nissen, J D; Jovanovic, I; Britten, J A & Barty, C J
System: The UNT Digital Library
ISENTROPIC COMPRESSION DATA ON LX-04 EXPLOSIVE AT 150?C USING THE Z ACCELERATOR (open access)

ISENTROPIC COMPRESSION DATA ON LX-04 EXPLOSIVE AT 150?C USING THE Z ACCELERATOR

Isentropic compression data was collected on LX-04 explosive (85% HMX and 15% Viton by weight) at 150 C using the Sandia National Laboratories Z accelerator facility. A ramp compression wave was applied to the explosive samples mounted on aluminum panels with VISAR interferometry measuring the sample and backing window interface velocity. Heating was obtained by wrapping band heaters around a thermal mass attached to each panel and temperatures were recorded by thermocouples at several locations on the panel. This work will outline the methods used, discuss the VISAR interface velocities, and present the preliminary data obtained on heated LX-04. These results demonstrate the ability to perform experiments on preheated samples to obtain isentrope data.
Date: July 28, 2005
Creator: Hare, D E; Vandersall, K S; Garcia, F; Davis, J; Hall, C & Forbes, J W
System: The UNT Digital Library
Photon Collider Technology Overview (open access)

Photon Collider Technology Overview

The photon collider option requires the generation of large amounts of laser power to drive the Compton scattering. The selection of the superconducting RF for the baseline of the ILC makes a recirculating solution attractive. A baseline for a recirculating cavity for the photon collider has been developed by a team [1, 2] at DESY/Zeuthen and the Max Born Institute. Similar cavities at much lower scale are being developed for laser wire and Compton polarimeter applications. The current status of the laser technology and a proposal for future development are reviewed. The impact of the {gamma}{gamma} experiment on the accelerator and detector is also discussed.
Date: July 28, 2005
Creator: Gronberg, J
System: The UNT Digital Library
Physical Characterization of RX-55-AE-5 a Formulation of 97.5 % 2,6-Diamino-3,5-Dinitropyrazine-1-Oxide (LLM-105) and 2.5% Viton A (open access)

Physical Characterization of RX-55-AE-5 a Formulation of 97.5 % 2,6-Diamino-3,5-Dinitropyrazine-1-Oxide (LLM-105) and 2.5% Viton A

With the use of modern tools such as molecular modeling on increasingly powerful computers, new materials can be evaluated by their structural activity relationships, SAR, and their approximate physical and chemical properties can be calculated in some cases with surprising accuracy. These new capabilities enable streamlined synthetic routes based on safety, performance and processing requirements, to name a few [1]. Current work includes both understanding properties of old explosives and measuring properties of new ones. The necessity to know and understand the properties of energetic materials is driven by the need to improve performance and enhance stability to various stimuli, such as thermal, friction and impact insult. This review will concentrate on the physical properties of RX-55-AE-5, which is formulated from heterocyclic explosive, 2,6-diamino-3,5-dinitropyrazine-1-oxide, LLM-105, and 2.5% Viton A. Differential scanning calorimetry, DSC, was used to measure a specific heat capacity, C{sub p}, of {approx} 0.950 J/g {center_dot} C, and a thermal conductivity, {kappa}, of {approx} 0.160 W/m {center_dot} C. The Lawrence Livermore National Laboratory (LLNL) code Kinetics05 and the Advanced Kinetics and Technology Solutions (AKTS) code Thermokinetics were both used to calculate Arrhenius kinetics for decomposition of LLM-105. Both obtained an activation energy barrier E {approx} 180 kJ mol{sup …
Date: July 28, 2005
Creator: Weese, R K; Burnham, A K; Turner, H C & Tran, T D
System: The UNT Digital Library