Resource Type

A 1.8 Mev K+ injector for the high current beam transport experiment fusion (open access)

A 1.8 Mev K+ injector for the high current beam transport experiment fusion

For the High Current Beam Transport Experiment (HCX) at LBNL, an injector is required to deliver up to 1.8 MV of 0.6 A K{sup +} beam with an emittance of {approx}1 p-mm-mrad. We have successfully operated a 10-cm diameter surface ionization source together with an electrostatic quadrupole (ESQ) accelerator to meet these requirements. The pulse length is {approx}4 {micro}s, firing at once every 10-15 seconds. By optimizing the extraction diode and the ESQ voltages, we have obtained an output beam with good current density uniformity, except for a small increase near the beam edge. Characterization of the beam emerging from the injector included measurements of the intensity profile, beam imaging, and transverse phase space. These data along with comparison to computer simulations provide the knowledge base for designing and understanding future HCX experiments.
Date: May 20, 2002
Creator: Kwan, J. W.; Bieniosek, F. M.; Henestroza, E.; Prost, L. & Seidl, P.
System: The UNT Digital Library
1-MeV-Electron Irradiation of GaInAsN Cells: Preprint (open access)

1-MeV-Electron Irradiation of GaInAsN Cells: Preprint

This conference paper describes the GaInAsN cells that are measured to retain 933% and 894% of their original efficiency after exposure to 5 X 1014 and 1 X 1015 cm-2 1-MeV electrons, respectively. The rate of degradation is not correlated with the performance at beginning of life (BOL). The depletion width remains essentially unchanged, increasing by< 1%. Temperature-coefficient data for GaInAsN cells are also presented. These numbers are used to project the efficiency of GaInAsN-containing multijunction cells. The GaInAsN junction is not currently predicted to increase the efficiencies of the multijunction cells. Nevertheless, GaInAsN-containing multijunction cell efficiencies are predicted to be comparable to those of the conventional structures, and even small improvements in the GaInAsN cell may lead to higher multijunction cell efficiencies, especially for high-radiation applications and when cell operating temperature is low.
Date: May 1, 2002
Creator: Kurtz, Sarah; King, R. R.; Edmondson, K. M.; Friedman, D. J. & Karam, N. H.
System: The UNT Digital Library
2-D and 3-D Elastic Modeling with Shared Seismic Models (open access)

2-D and 3-D Elastic Modeling with Shared Seismic Models

Several elastic models, both 2-D and 3-D, are being built for use in calculating synthetic elastic seismic data. The models will be made available to the research community, along with the synthetic data that are being calculated from them. These shared models have been proposed or contributed by participants in a collaborative industry, national laboratory, and university research project. The purpose of the modeling is to provide synthetic data to better understand elastic wave propagation and the effects of structural and stratigraphic complexities. The 2-D models are easier to design and change and synthetic calculations can be run relatively quickly in them. It will be possible to alter their layer properties and calculate time-lapse data sets from them. Field data will be available to accompany many of the 2-D models. 3-D models are more realistic, but more difficult to design and change. They also require considerably more computing resources to calculate synthetic data from them. A new 3-D model is being designed, and will be used for computing synthetic elastic data.
Date: April 30, 2002
Creator: House, L.; Marfurt, K. J.; Larsen, S. & Martin, G. S.
System: The UNT Digital Library
A 2-Liter, 2000 MPa Air Source for the Radiatively Driven Hypersonic Wind Tunnel (open access)

A 2-Liter, 2000 MPa Air Source for the Radiatively Driven Hypersonic Wind Tunnel

The A2 LITE is a 2 liter, 2000 MPa, 750 K ultra-high pressure (UHP) vessel used to demonstrate UHP technology and to provide an air flow for wind tunnel nozzle development. It is the largest volume UHP vessel in the world. The design is based on a 100:1 pressure intensification using a hydraulic ram as a low pressure driver and a three-layer compound cylinder UHP section. Active control of the 900 mm piston stroke in the 63.5 mm bore permits pressure-time profiles ranging from static to constant pressure during flow through a 1 mm throat diameter nozzle for 1 second.
Date: May 30, 2002
Creator: Costantino, M & Lofftus, D
System: The UNT Digital Library
3-D elastic wave scattering by a layer containing vertical periodic fractures (open access)

3-D elastic wave scattering by a layer containing vertical periodic fractures

None
Date: April 30, 2002
Creator: Nakagawa, Seiji; Nihei, Kurt T.; Myer, Larry R. & Majer, Ernest L.
System: The UNT Digital Library
A 3-D ray-trace model for an AMR code on distributed processors (open access)

A 3-D ray-trace model for an AMR code on distributed processors

Distributed memory AMR codes provide a special challenge for laser ray-trace modeling. For RAGE we follow the energy-carrying rays through each cell, checking for crossings which require collection a new cell index (1 of 9 in 2D). Density gradients for ray deflections can be calculated 'on the fly.' Substantial excursions must be made from the legacy PIC particle area-weighting approach, but this serves as a useful 1st step. Similarly, IDL now offers a quick graphical rendering, while ENSIGHT graphics beautifully captures the 3D light refraction and deposition.
Date: January 1, 2002
Creator: Mason, R. J. (Rodney J.)
System: The UNT Digital Library
3-D surface profile measurements of large x-ray synchrotron radiation mirrors using stitching interferometry. (open access)

3-D surface profile measurements of large x-ray synchrotron radiation mirrors using stitching interferometry.

Stitching interferometry, using small-aperture, high-resolution, phase-measuring interferometry, has been proposed for quite some time now as a metrology technique to obtain 3-dimensional profiles of surfaces of oversized optical components and substrates. The aim of this work is to apply this method to the specific case of long grazing-incidence x-ray mirrors, such as those used in beamlines at synchrotron radiation facilities around the world. Both fabrication and characterization of these mirrors would greatly benefit from this technique because it offers the potential for providing measurements with accuracy and resolution better than those obtained using existing noncontact laser profilers, such as the long trace profiler (LTP). Measurement data can be used as feedback for computer-controlled fabrication processes to correct for possible topography errors. The data can also be used for simulating and predicting mirror performance under realistic conditions. A semiautomated stitching system was built and tested at the X-ray Optics Metrology Laboratory of the Advanced Photon Source at Argonne National Laboratory. The initial objective was to achieve a measurement sensitivity on the order of 1 {micro}rad rms. Preliminary tests on a 1 m-long x-ray mirror showed system repeatability of less than 0.6 {micro}rad rms. This value is comparable to that of a …
Date: September 12, 2002
Creator: Assoufid, L.; Bray, M.; Qian, J. & Shu, D.
System: The UNT Digital Library
8-(Hydroxymethyl)-3,N4-etheno-C, a potential carcinogenic glycidaldehyde product, miscodes in vitro using mammalian DNA polymerases (open access)

8-(Hydroxymethyl)-3,N4-etheno-C, a potential carcinogenic glycidaldehyde product, miscodes in vitro using mammalian DNA polymerases

None
Date: January 28, 2002
Creator: Singer, B.; Medina, Michael; Zhang, Yanbin; Wang, Zhigang; Guliaev, Anton B. & Hang, Bo
System: The UNT Digital Library
20% Partial Siberian Snake in the AGS. (open access)

20% Partial Siberian Snake in the AGS.

An 11.4% partial Siberian snake was used to successfully accelerate polarized proton through a strong intrinsic depolarizing spin resonance in the AGS. No noticeable depolarization was observed. This opens up the possibility of using a 20% to 30% partial Siberian snake in the AGS to overcome all weak and strong depolarizing spin resonances. Some design and operation issues of the new partial Siberian snake are discussed.
Date: November 6, 2002
Creator: Huang, H.; Bai, M.; Brown, K. A.; Glenn, W.; Luccio, A. U.; MacKay, W. W. et al.
System: The UNT Digital Library
25 years of technical advances in RFQ accelerators (open access)

25 years of technical advances in RFQ accelerators

The radio frequency quadrupole (RFQ) accelerator began as 'The ion linear accelerator with space-uniform strong focusing' conceived by I. M. Kapchinskii and V. A. Teplyakove. In 1979, R. H. Stokes, K. R. Crandall, J. E. Stovall and D. A. Swenson gave this concept the name RFQ. And by 1983, at least 15 laboratories throughout the world were working on various FWQ designs. In the early years, there were many types of geometry considered for the RFQ, but only a few types have survived. The two cavity geometries now used in almost all RFQs are the 4-vane and 4-rod structures. The 4-vane structure is the most popular because its operating frequency range (80 to -500 MHz) is suitable for light ions. Heavy ions require low frequencies (below 200 MHz). Because the 4-rod structure has smaller transverse dimensions than a 4-vane RFQ at the same frequency, the 4-rod RFQ is often preferred for these applications. This paper will describe how the RFQ accelerates and focuses the beam. The paper also discusses some of the important technical advances in designing and building RFQs.
Date: January 1, 2002
Creator: Young, L. M. (Lloyd M.)
System: The UNT Digital Library
100-Picometer Interferometry for EUVL (open access)

100-Picometer Interferometry for EUVL

Future extreme ultraviolet lithography (EWL) steppers will, in all likelihood, have six-mirror projection cameras. To operate at the diffraction limit over an acceptable depth of focus each aspheric mirror will have to be fabricated with an absolute figure accuracy approaching 100 pm rms. We are currently developing visible light interferometry to meet this need based on modifications of our present phase shifting diffraction interferometry (PSDI) methodology where we achieved an absolute accuracy of 250pm. The basic PSDI approach has been further simplified, using lensless imaging based on computational diffractive back-propagation, to eliminate auxiliary optics that typically limit measurement accuracy. Small remaining error sources, related to geometric positioning, CCD camera pixel spacing and laser wavelength, have been modeled and measured. Using these results we have estimated the total system error for measuring off-axis aspheric EUVL mirrors with this new approach to interferometry.
Date: March 18, 2002
Creator: Sommargren, G. E.; Phillion, D. W.; Johnson, M. A.; Nguyen, N. O.; Barty, A.; Snell, F. J. et al.
System: The UNT Digital Library
148-Gd cross section measurements for accelerator target facilities (open access)

148-Gd cross section measurements for accelerator target facilities

In a series of experiments at LANSCE's WNR facility, 148Gdp roduction was measured for 600- and 800-MeV protons on tungsten, tantalum, and gold. These experiments used 3 pm thin W, Ta, and Au foils and 10 pm thin A1 activation foils, Spallation yields were determined for many short-lived and long-lived spallation products with these foils using gamma and alpha spectroscopy.
Date: January 1, 2002
Creator: Corzine, R. K. (R. Karen); Pitcher, E. J. (Eric J.); Devlin, M. J. (Matthew J.) & Hertel, N. E. (Nolan E.)
System: The UNT Digital Library
205 kA pulse power supply for neutrino focusing horns (open access)

205 kA pulse power supply for neutrino focusing horns

A new underground beamline is being constructed at Fermilab to generate and focus a beam of neutrinos on a detector 450 miles away in Soudan, Minnesota. A compact modulator utilizing capacitive energy storage and SCRs as the switching element has been built and tested at Fermilab. The 0.9 F capacitor bank operates at less than 1 kV. It delivers its output of up to 240 kA directly to the two series connected focusing horns via a multi-layer radiation hard stripline [1]. Dual pulse width capability allows for ready selection of 5.2 ms, for slow beam spills, or 2.6 ms operation for reduced thermal stresses on the focusing horns during fast spill. Intended for installation in an underground equipment room, the design incorporates several novel features to facilitate transport, installation, and maintenance. Various designs were examined to arrive at the most economical approach for providing the high pulse currents to the horns located in the very high radiation field, up to 3 x 10{sup 7} kRads/yr absorbed dose of the beamline. These included charge recovery and electronic polarity reversal systems. The direct coupling approach was selected for its overall economy and compactness. The system has been operational for several months and …
Date: June 21, 2002
Creator: Kenneth R. Bourkland, Kevin Roon and David Tinsley
System: The UNT Digital Library
360 Degree Photography to Decrease Exposure, Increase Safety & Minimize Waste (open access)

360 Degree Photography to Decrease Exposure, Increase Safety & Minimize Waste

High-resolution digital cameras, in conjunction with software techniques. make possible 360{sup o} photos that allow a person to look all around, up and dawn, and zoom in or out. The software provides the opportunity to attach other information to a 360{sup o} photo such as sound tiles, flat photos (providing additional detail about what is behind a panel or around a corner) and text (Information which can be used to show radiological conditions or identify other hazards not readily visible). The software also allows other 360{sup o} photos to be attached creating a virtual tour where the user can move from area to area, and stop, study and zoom in on areas of interest. A virtual tour of a building or room can be used for facility documentation, informing management and others, work planning and orientation, and training, thus minimizing the need to re-enter hazardous radioactive areas. Reducing entries decreases exposure, increases safety and minimizes waste.
Date: January 31, 2002
Creator: LeBaron, G. J.
System: The UNT Digital Library
805 MHz and 201 MHz RF cavity development for MUCOOL (open access)

805 MHz and 201 MHz RF cavity development for MUCOOL

A muon cooling channel calls for very high acceleratinggradient RF structures to restore the energy lost by muons in theabsorbers. The RF structures have to be operated in a strong magneticfield and thus the use of superconducting RF cavities is excluded. Toachieve a high shunt impedance while maintaining a large enough apertureto accommodate a large transverse emittance muon beam, the cavity designadopted is a pillbox-like geometry with thin Be foils to terminate theelectromagnetic field at the cavity iris. The possibility of using gridsof thin-walled metallic tubes for the termination is also being explored.Many of the RF-related issues for muon cooling channels are being studiedboth theoretically and experimentally using an 805 MHz cavity that has apillbox-like geometry with thin Be windows to terminate the cavityaperture. The design and performance of this cavity are reported here.High-power RF tests of the 805 MHz cavity are in progress at Lab G inFermilab. The cavity has exceeded its design gradient of 30 MV/m,reaching 34 MV/m without external magnetic field. No surface damage wasobserved at this gradient. The cavity is currently under conditioning atLab G with an external magnetic field of 2.5 T. We also present here a201 MHz cavity design for muoncooling channels. The proposed …
Date: October 10, 2002
Creator: DLi@lbl.gov
System: The UNT Digital Library
938 nm Nd-Doped High Power Cladding Pumped Fiber Amplifier (open access)

938 nm Nd-Doped High Power Cladding Pumped Fiber Amplifier

2.1W of 938nm light has been produced in an Nd{sup 3+} doped fiber amplifier. Wavelength dependent bend losses can be employed to minimize 1088nm amplified spontaneous emission giving the optical fiber a distinct advantage over bulk media.
Date: September 19, 2002
Creator: Dawson, J; Beach, R; Drobshoff, A; Liao, Z; Pennington, D; Payne, S et al.
System: The UNT Digital Library
16th National Conference of Black Physics Students - Physics: Science That Unlocks the Secrets of Nature (open access)

16th National Conference of Black Physics Students - Physics: Science That Unlocks the Secrets of Nature

16th National Conference of Black Physics Students - The agenda and its report.
Date: March 13, 2002
Creator: unknown
System: The UNT Digital Library
2002 Gordon Research Conference on CATALYSIS. Final Progress Report (open access)

2002 Gordon Research Conference on CATALYSIS. Final Progress Report

The Gordon Research Conference (GRC) on CATALYSIS was held at Colby-Sawyer College from 6/23/02 thru 6/28/02. The Conference was well-attended with 118 participants. The attendees represented the spectrum of endeavor in this field coming from academia, industry, and government laboratories, both U.S. and foreign scientists, senior researchers, young investigators, and students.
Date: June 28, 2002
Creator: unknown
System: The UNT Digital Library
2002 Gordon Research Conference on Molecular Evolution (open access)

2002 Gordon Research Conference on Molecular Evolution

Emphasis was placed on current unpublished research and discussion of the future target areas in this field.
Date: January 18, 2002
Creator: unknown
System: The UNT Digital Library
2002 Gordon Research Conference on Mutagenesis. Final Progress Report (open access)

2002 Gordon Research Conference on Mutagenesis. Final Progress Report

The Gordon Research Conference (GRC) on MUTAGENESIS was held at Bates College from 7/28/02 thru 8/2/02. The Conference was well-attended with 157 participants. The attendees represented the spectrum of endeavor in this field coming from academia, industry, and government laboratories, both U.S. and foreign scientists, senior researchers, young investigators, and students.
Date: August 2, 2002
Creator: unknown
System: The UNT Digital Library
2002 Gordon Research Conference on Reversible Associations in Structural & Molecular Biology (open access)

2002 Gordon Research Conference on Reversible Associations in Structural & Molecular Biology

Emphasis was placed on current unpublished research and discussion of the future target areas in this field.
Date: February 15, 2002
Creator: unknown
System: The UNT Digital Library
2002 Review of Neutron and Non Neutron Nuclear Data (open access)

2002 Review of Neutron and Non Neutron Nuclear Data

Review articles are in preparation for the 2003 edition of the CRC's Handbook of Chemistry and Physics dealing with both non-neutron and neutron nuclear data. Highlights include: withdrawal of the claim for discovery of element 118; new measurements of isotopic abundances have led to changes for many elements; a new set of recommended standards for calibration of {gamma}-ray energies have been published for many nuclides; new half-life measurements reported for very short lived isotopes, many long-lived nuclides and {beta}{beta} decay measurements for quasi-stable nuclides; a new reassessment of spontaneous fission (sf) half-lives for ground state nuclides, distinguishing half-lives from sf decay and cluster decay half-lives and the new cluster-fission decay; charged particle cross sections, (n,p) and (n,{alpha}) measurements for thermal neutrons incident on light nuclides; new thermal (n,{gamma}) cross sections and neutron resonance integrals measured. Details are presented.
Date: August 18, 2002
Creator: Holden, N. E.
System: The UNT Digital Library
2D/3D quench simulation using ANSYS for epoxy impregnated Nb3Sn high field magnets (open access)

2D/3D quench simulation using ANSYS for epoxy impregnated Nb3Sn high field magnets

A quench program using ANSYS is developed for the high field collider magnet for three-dimensional analysis. Its computational procedure is explained. The quench program is applied to a one meter Nb{sub 3}Sn high field model magnet, which is epoxy impregnated. The quench simulation program is used to estimate the temperature and mechanical stress inside the coil as well as over the whole magnet. It is concluded that for the one meter magnet with the presented cross section and configuration, the thermal effects due to the quench is tolerable. But we need much more quench study and improvements in the design for longer magnets.
Date: September 19, 2002
Creator: al., Ryuji Yamada et
System: The UNT Digital Library
2nd Annual Los Alamos Plutonium Metal Standard Exchange Workshop : "preliminary" results (open access)

2nd Annual Los Alamos Plutonium Metal Standard Exchange Workshop : "preliminary" results

The Rocky Flats Plutonium (Pu) Metal Sample Exchange program was conducted to insure the quality and intercomparability of measurements such as Pu assay, Pu isotopics, and impurity analyses. This program was discontinued in 1989 after more than 30 years. Los Alamos National Laboratory (LANL) has reestablished the Pu metal exchange program. During the first year, five DOE facilities, Argonne East, Argonne West, Livermore, Los Alamos, and New Brunswick Laboratory, Savannah River and the Atomic Weapons Establishment (AWE)' at Aldermaston are participating in the program. Plutonium metal samples are being prepared and distributed to the various sites primarily for destructive measurements for elemental concentration, isotopic abundance, and both metallic and nonmetallic impurity levels. The program is intended to provide independent verification of analytical measurement capability for each participating facility and to allow problems to be identified. Significants achievements in FY02 will be described. Results from category 1 elements and comparisons with Rocky Flats standards exchange metal historical data will also be presented. The roles and responsibilities of LANL and the external laboratories have been defined.
Date: January 1, 2002
Creator: Tandon, L. (Lav) & Slemmons, A. K. (Alice K.)
System: The UNT Digital Library