Simulations of RF capture with barrier bucket in booster at injection (open access)

Simulations of RF capture with barrier bucket in booster at injection

As part of the effort to increase the number of ions per bunch in RHIC, a new scheme for RF capture of EBIS ions in Booster at injection has been developed. The scheme was proposed by M. Blaskiewicz and J.M. Brennan. It employs a barrier bucket to hold a half turn of beam in place during capture into two adjacent harmonic 4 buckets. After acceleration, this allows for 8 transfers of 2 bunches from Booster into 16 buckets on the AGS injection porch. During the Fall of 2011 the necessary hardware was developed and implemented by the RF and Controls groups. The scheme is presently being commissioned by K.L. Zeno with Au32+ ions from EBIS. In this note we carry out simulations of the RF capture. These are meant to serve as benchmarks for what can be achieved in practice. They also allow for an estimate of the longitudinal emittance of the bunches on the AGS injection porch.
Date: January 23, 2012
Creator: Gardner, C. J.
Object Type: Report
System: The UNT Digital Library
Low-Cost Organic Moderator-Coolants for Nuclear Reactors (open access)

Low-Cost Organic Moderator-Coolants for Nuclear Reactors

None
Date: December 23, 1963
Creator: Gardner, L. E.; Hutchinson, W. M. & Hillyer, J. C.
Object Type: Report
System: The UNT Digital Library
Evidence for the Absence of Gluon Orbital Angular Momentum in the Nucleon (open access)

Evidence for the Absence of Gluon Orbital Angular Momentum in the Nucleon

The Sivers mechanism for the single-spin asymmetry in unpolarized lepton scattering from a transversely polarized nucleon is driven by the orbital angular momentum carried by its quark and gluon constituents, combined with QCD final-state interactions. Both quark and gluon mechanisms can generate such a single-spin asymmetry, though only the quark mechanism can explain the small single-spin asymmetry measured by the COMPASS collaboration on the deuteron, suggesting the gluon mechanism is small relative to the quark mechanism. We detail empirical studies through which the gluon and quark orbital angular momentum contributions, quark-flavor by quark-flavor, can be elucidated.
Date: August 23, 2006
Creator: Brodsky, S. J. & Gardner, S.
Object Type: Article
System: The UNT Digital Library
Measurements and Modeling of Eddy Current Effects in BNL's AGS Booster. (open access)

Measurements and Modeling of Eddy Current Effects in BNL's AGS Booster.

Recent beam experiments at BNL's AGS Booster have enabled us to study in more detail the effects of eddy currents on the lattice structure and our control over the betatron tune. The Booster is capable of operating at ramp rates as high as 9 T/sec. At these ramp rates eddy currents in the vacuum chambers significantly alter the fields and gradients seen by the beam as it is accelerated. The Booster was designed with these effects in mind and to help control the field uniformity and linearity in the Booster Dipoles special vacuum chambers were designed with current windings to negate the affect of the induced eddy currents. In this report results from betatron tune measurements and eddy current simulations will be presented. We will then present results from modeling the accelerator using the results of the magnetic field simulations and compare these to the measurements.
Date: June 23, 2006
Creator: Brown, K. A.; Ahrens, L.; Gardner, C.; Glenn, J. W.; Harvey, M.; Meng, W. et al.
Object Type: Article
System: The UNT Digital Library
Virtual PCR (open access)

Virtual PCR

The polymerase chain reaction (PCR) stands among the keystone technologies for analysis of biological sequence data. PCR is used to amplify DNA, to generate many copies from as little as a single template. This is essential, for example, in processing forensic DNA samples, pathogen detection in clinical or biothreat surveillance applications, and medical genotyping for diagnosis and treatment of disease. It is used in virtually every laboratory doing molecular, cellular, genetic, ecologic, forensic, or medical research. Despite its ubiquity, we lack the precise predictive capability that would enable detailed optimization of PCR reaction dynamics. In this LDRD, we proposed to develop Virtual PCR (VPCR) software, a computational method to model the kinetic, thermodynamic, and biological processes of PCR reactions. Given a successful completion, these tools will allow us to predict both the sequences and concentrations of all species that are amplified during PCR. The ability to answer the following questions will allow us both to optimize the PCR process and interpret the PCR results: What products are amplified when sequence mixtures are present, containing multiple, closely related targets and multiplexed primers, which may hybridize with sequence mismatches? What are the effects of time, temperature, and DNA concentrations on the concentrations …
Date: February 23, 2006
Creator: Gardner, S N; Clague, D S; Vandersall, J A; Hon, G & Williams, P L
Object Type: Report
System: The UNT Digital Library
Setup and performance of RHIC for the 2008 run with deuteron-gold collisions. (open access)

Setup and performance of RHIC for the 2008 run with deuteron-gold collisions.

This year (2008) deuterons and gold ions were collided in the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL) for the first time since 2003. The setup and performance of the collider for the 2008 run is reviewed with a focus on improvements that have led to an order of magnitude increase in luminosity over that achieved in the 2003 run.
Date: June 23, 2008
Creator: Gardner,C.; Abreu, N.P.; Ahren, L.; Alessi, J.; Bai, M. & al., et
Object Type: Article
System: The UNT Digital Library
Effect of a Decelerating Grid on Current from an Ion Source (open access)

Effect of a Decelerating Grid on Current from an Ion Source

Abstract: "A theoretical criterion is given for the conditions under which the ions from an ion source may be decelerated by a decelerating grid, following the accelerating grid which extracts ions from the emitter, without causing a reduction in the current supplied by the source."
Date: February 23, 1955
Creator: Bing, George F., 1924-; Gardner, C. S. & Northrop, Theodore G.
Object Type: Report
System: The UNT Digital Library
U.S. Circuit and District Court Nominations by President George W. Bush During the 107th-109th Congresses (open access)

U.S. Circuit and District Court Nominations by President George W. Bush During the 107th-109th Congresses

None
Date: January 23, 2007
Creator: unknown
Object Type: Report
System: The UNT Digital Library
AGS polarized proton operation in run 8. (open access)

AGS polarized proton operation in run 8.

Dual partial snake scheme has been used for the Brookhaven AGS (Alternating Gradient Synchrotron) polarized proton operation for several years. It has provided polarized proton beams with 1.5 x 10{sup 11} intensity and 65% polarization for RHIC spin program. There is still residual polarization loss. Several schemes such as putting horizontal tune into the spin tune gap, and injection-on-the-fly were tested in the AGS to mitigate the loss. This paper presents the experiment results and analysis.
Date: June 23, 2008
Creator: Huang, H.; Ahrens, L.; Bai, M.; Brown, K. A.; Gardner, C.; Glenn, J. W. et al.
Object Type: Article
System: The UNT Digital Library
Lattices for High-Power Proton Beam Acceleration and Secondary Beam Collection and Cooling. (open access)

Lattices for High-Power Proton Beam Acceleration and Secondary Beam Collection and Cooling.

Rapid cycling synchrotrons are used to accelerate high-intensity proton beams to energies of tens of GeV for secondary beam production. After primary beam collision with a target, the secondary beam can be collected, cooled, accelerated or decelerated by ancillary synchrotrons for various applications. In this paper, we first present a lattice for the main synchrotron. This lattice has: (a) flexible momentum compaction to avoid transition and to facilitate RF gymnastics (b) long straight sections for low-loss injection, extraction, and high-efficiency collimation (c) dispersion-free straights to avoid longitudinal-transverse coupling, and (d) momentum cleaning at locations of large dispersion with missing dipoles. Then, we present a lattice for a cooler ring for the secondary beam. The momentum compaction across half of this ring is near zero, while for the other half it is normal. Thus, bad mixing is minimized while good mixing is maintained for stochastic beam cooling.
Date: June 23, 2006
Creator: Wang, S.; Wei, J.; Brown, K.; Gardner, C.; Lee, Y. Y.; Lowenstein, D. et al.
Object Type: Article
System: The UNT Digital Library
Modulus dispersion and attenuation in tuff and granite (open access)

Modulus dispersion and attenuation in tuff and granite

The effects of loading frequency, strain amplitude, and saturation on elastic moduli and attenuation have been measured in samples of the Topopah Spring Member welded tuff. Four different laboratory techniques have been used to determine Young`s modulus and extensional wave attenuation at frequencies ranging from 10{sup {minus}2} to 10{sup 6} Hz. The results are compared with data acquired for Sierra White granite under the same conditions. The modulus and attenuation in room dry samples remain relatively constant over frequency. Frequency dependent attenuation and modulus dispersion are observed in the saturated samples and are attributed to fluid flow and sample size. The properties of tuff were independent of strain amplitude in room dry and saturated conditions.
Date: December 23, 1991
Creator: Haupt, R. W.; Martin, R. J., III; Tang, X.; Dupree, W. J. & Price, R. H.
Object Type: Report
System: The UNT Digital Library
Local indium segregation and band structure in high efficiencygreen light emitting InGaN/GaN diodes (open access)

Local indium segregation and band structure in high efficiencygreen light emitting InGaN/GaN diodes

GaN/InGaN light emitting diodes (LEDs) are commercialized for lighting applications because of the cost efficient way that they produce light of high brightness. Nevertheless, there is significant room for improving their external emission efficiency from typical values below 10 percent to more than 50 percent, which are obtainable by use of other materials systems that, however, do not cover the visible spectrum. In particular, green-light emitting diodes fall short in this respect, which is troublesome since the human eye is most sensitive in this spectral range. In this letter advanced electron microscopy is used to characterize indium segregation in InGaN quantum wells of high-brightness, green LEDs (with external quantum efficiency as high as 15 percent at 75 A/cm2). Our investigations reveal the presence of 1-3 nm wide indium rich clusters in these devices with indium concentrations as large as 0.30-0.40 that narrow the band gap locally to energies as small as 2.65 eV.
Date: November 23, 2004
Creator: Jinschek, Joerg R.; Erni, Rolf; Gardner, Nathan F.; Kim, AndrewY. & Kisielowski, Christian
Object Type: Article
System: The UNT Digital Library
Injection and Acceleration of Au31+ in the BNL AGS. (open access)

Injection and Acceleration of Au31+ in the BNL AGS.

Injection and acceleration of ions in a lower charge state reduces space charge effects, and, if further elcctron stripping is needed, may allow elimination of a stripping stage and the associated beam losses. The former is of interest to the accelerators in the GSI FAIR complex, the latter for BNL RHIC collider operation at energies lower than the current injection energy. Lower charge state ions, however, have a higher likelihood of electron stripping which can lead to dynamic pressures rises and subsequent beam losses. We report on experiments in the AGS where Au{sup 31+} ions were injected and accelerated instead of the normally used Au{sup 77+} ions. Beam intensities and the average pressure in the AGS ring are recorded, and compared with calculations for dynamic pressures and beam losses. The experimental results will be used to benchmark the StrahlSim dynamic vacuum code and will be incorporated in the GSI FAIR SIS100 design.
Date: June 23, 2008
Creator: Fischer, W.; Ahrens, L.; Brown, K.; Gardner, C.; Glenn, W.; Huang, H. et al.
Object Type: Article
System: The UNT Digital Library
New Class of CW High-Power Diode-Pumped Alkali Lasers (DPALs) (open access)

New Class of CW High-Power Diode-Pumped Alkali Lasers (DPALs)

The new class of diode-pumped alkali vapor lasers (DPALs) offers high efficiency cw laser radiation at near-infrared wavelengths: cesium 895 nm, rubidium 795 nm, and potassium 770 nm. The working physical principles of DPALs will be presented. Initial 795 nm Rb and 895 nm Cs laser experiments performed using a titanium sapphire laser as a surrogate pump source demonstrated DPAL slope power conversion efficiencies in the 50-70% range, in excellent agreement with device models utilizing only literature spectroscopic and kinetic data. Using these benchmarked models for Rb and Cs, optimized DPALs with optical-optical efficiencies >60%, and electrical efficiencies of 25-30% are projected. DPAL device architectures for near-diffraction-limited power scaling into the high kilowatt power regime from a single aperture will be described. DPAL wavelengths of operation offer ideal matches to silicon and gallium arsenide based photovoltaic power conversion cells for efficient power beaming.
Date: March 23, 2004
Creator: Krupke, W F; Beach, R J; Kanz, V K; Payne, S A & Early, J T
Object Type: Article
System: The UNT Digital Library
RHIC Performance During the FY10 200 GeV Au+Au Heavy Ion Run (open access)

RHIC Performance During the FY10 200 GeV Au+Au Heavy Ion Run

Since the last successful RHIC Au+Au run in 2007 (Run-7), the RHIC experiments have made numerous detector improvements and upgrades. In order to benefit from the enhanced detector capabilities and to increase the yield of rare events in the acquired heavy ion data a significant increase in luminosity is essential. In Run-7 RHIC achieved an average store luminosity of <L> = 12 x 10{sup 26} cm{sup -2} s{sup -1} by operating with 103 bunches (out of 111 possible), and by squeezing to {beta}* = 0.85 m. This year, Run-10, we achieved <L> = 20 x 10{sup 26} cm{sup -2} s{sup -1}, which put us an order of magnitude above the RHIC design luminosity. To reach these luminosity levels we decreased {beta}* to 0.75 m, operated with 111 bunches per ring, and reduced longitudinal and transverse emittances by means of bunched-beam stochastic cooling. In addition we introduced a lattice to suppress intra-beam scattering (IBS) in both RHIC rings, upgraded the RF control system, and separated transition crossing times in the two rings. We present an overview of the changes and the results of Run-10 performance.
Date: May 23, 2010
Creator: Brown, K. A.; Ahrens, L.; Bai, M.; Beebe-Wang, J.; Blaskiewicz, M.; Brennan, J. et al.
Object Type: Article
System: The UNT Digital Library
RHIC Performance as a 100 GeV Polarized Proton Collider in Run-9 (open access)

RHIC Performance as a 100 GeV Polarized Proton Collider in Run-9

During the second half of Run-9, the Relativisitc Heavy Ion Collider (RHIC) provided polarized proton collisions at two interaction points. The spin orientation of both beams at these collision points was controlled by helical spin rotators, and physics data were taken with different orientations of the beam polarization. Recent developments and improvements will be presented, as well as luminosity and polarization performance achieved during Run-9.
Date: May 23, 2010
Creator: Montag, C.; Ahrens, L.; Bai, M.; Beebe-Wang, J.; Blaskiewicz, M.; Brennan, J. M. et al.
Object Type: Article
System: The UNT Digital Library
Observation of off-Hugoniot shocked states with ultrafast time resolution (open access)

Observation of off-Hugoniot shocked states with ultrafast time resolution

We apply ultrafast single shot interferometry to determine the pressure and density of argon shocked from up to 7.8 GPa static initial pressure in a diamond anvil cell. This method enables the observation of thermodynamic states distinct from those observed in either single shock or isothermal compression experiments, and the observation of ultrafast dynamics in shocked materials. We also present a straightforward method for interpreting ultrafast shock wave data which determines the index of refraction at the shock front, and the particle and shock velocities for shock waves in transparent materials. Based on these methods, we observe shocked thermodynamic states between the room temperature isotherm of argon and the shock adiabat of cryogenic argon at final shock pressures up to 28 GPa.
Date: February 23, 2010
Creator: Armstrong, M; Crowhurst, J; Bastea, S & Zaug, J
Object Type: Article
System: The UNT Digital Library
Stemming options and their effect on containment (open access)

Stemming options and their effect on containment

In more than 17 years of studying underground nuclear explosions, LLL has developed containment procedures that include a stemming plan. Stemming plans can be divided into either layered or continuous forms. There are marked differences between standards for these forms. The materials used in the continuous plan must meet more stringent specifications; as a consequence, they are more expensive. Both plans have been successful since the Baneberry Event. Both plans must meet the following requirements: provide a plug sufficient to match the overburden density of earth; contain radioactive gases at the lowest possible depth; minimize the generation of noncondensable gases (such as CO/sub 2/); minimize gas flow rates during the early post-detonation stages when cavity pressure is high; and be compatible with the experiment and its diagnostics. LLL experience in developing containment procedures is reviewed, and the reasons for the adoption of LLL's continuous stemming plan are reported. (LCL)
Date: June 23, 1976
Creator: Day, J. A.
Object Type: Report
System: The UNT Digital Library
LOFT DTT rake pin stress analysis (open access)

LOFT DTT rake pin stress analysis

A stress analysis of the 3/8-inch and 1/4-inch pins which hold the rake assembly to the flange was performed and shows stresses to be lower than the Class 1 allowables of the ASME Boiler and Pressure Vessel Code. The alternating pin stresses were found to be below the endurance limit and fatigue failure will not occur. The rake assembly was assumed to be loaded by steady drag and lift forces and alternating vortex shedding forces.
Date: January 23, 1979
Creator: Mosby, W.R.
Object Type: Report
System: The UNT Digital Library
Mechanisms of transition-metal gettering in silicon (open access)

Mechanisms of transition-metal gettering in silicon

The atomic process, kinetics, and equilibrium thermodynamics underlying the gettering of transition-metal impurities in Si are reviewed from a mechanistic perspective. Methods for mathematical modeling of gettering are reviewed and illustrated. Needs for further research are discussed.
Date: March 23, 2000
Creator: Myers, Samuel M., Jr.; Seibt, M. & Schroter, W.
Object Type: Article
System: The UNT Digital Library
Advanced numerical methods and software approaches for semiconductor device simulation (open access)

Advanced numerical methods and software approaches for semiconductor device simulation

In this article the authors concisely present several modern strategies that are applicable to drift-dominated carrier transport in higher-order deterministic models such as the drift-diffusion, hydrodynamic, and quantum hydrodynamic systems. The approaches include extensions of upwind and artificial dissipation schemes, generalization of the traditional Scharfetter-Gummel approach, Petrov-Galerkin and streamline-upwind Petrov Galerkin (SUPG), entropy variables, transformations, least-squares mixed methods and other stabilized Galerkin schemes such as Galerkin least squares and discontinuous Galerkin schemes. The treatment is representative rather than an exhaustive review and several schemes are mentioned only briefly with appropriate reference to the literature. Some of the methods have been applied to the semiconductor device problem while others are still in the early stages of development for this class of applications. They have included numerical examples from the recent research tests with some of the methods. A second aspect of the work deals with algorithms that employ unstructured grids in conjunction with adaptive refinement strategies. The full benefits of such approaches have not yet been developed in this application area and they emphasize the need for further work on analysis, data structures and software to support adaptivity. Finally, they briefly consider some aspects of software frameworks. These include dial-an-operator approaches …
Date: March 23, 2000
Creator: CAREY,GRAHAM F.; PARDHANANI,A.L. & BOVA,STEVEN W.
Object Type: Article
System: The UNT Digital Library
Permanganate Treatment of DNAPLs in Reactive Barriers and Source Zone Flooding Schemes (open access)

Permanganate Treatment of DNAPLs in Reactive Barriers and Source Zone Flooding Schemes

Permanganate is a simple and common chemical, which has proven useful in oxidizing common chlorinated solvents. Due to the nature of oxidation, the byproducts and products are much less harmful than those from reduction-type remedial schemes, and the degradation process is rapid. The main goal of this project is to understand oxidative destruction of chlorinated solvents using potassium permanganate. The study has provided a theoretical basis for evaluating the feasibility of in-situ applications, to couple kinetic reaction with transport models, and to develop an appropriate field test for further assessing the approach.
Date: December 23, 2003
Creator: Schwartz, F. W. & Zhang, H.
Object Type: Report
System: The UNT Digital Library
Hanford Tanks 241-C-203 and 241 C 204: Residual Waste Contaminant Release Model and Supporting Data (open access)

Hanford Tanks 241-C-203 and 241 C 204: Residual Waste Contaminant Release Model and Supporting Data

This report was revised in May 2007 to correct 90Sr values in Chapter 3. The changes were made on page 3.9, paragraph two and Table 3.10; page 3.16, last paragraph on the page; and Tables 3.21 and 3.31. The rest of the text remains unchanged from the original report issued in October 2004. This report describes the development of release models for key contaminants that are present in residual sludge remaining after closure of Hanford Tanks 241-C-203 (C-203) and 241-C-204 (C-204). The release models were developed from data generated by laboratory characterization and testing of samples from these two tanks. Key results from this work are (1) future releases from the tanks of the primary contaminants of concern (99Tc and 238U) can be represented by relatively simple solubility relationships between infiltrating water and solid phases containing the contaminants; and (2) high percentages of technetium-99 in the sludges (20 wt% in C-203 and 75 wt% in C-204) are not readily water leachable, and, in fact, are very recalcitrant. This is similar to results found in related studies of sludges from Tank AY-102. These release models are being developed to support the tank closure risk assessments performed by CH2M HILL Hanford Group, …
Date: May 23, 2007
Creator: Deutsch, William J.; Krupka, Kenneth M.; Lindberg, Michael J.; Cantrell, Kirk J.; Brown, Christopher F. & Schaef, Herbert T.
Object Type: Report
System: The UNT Digital Library
Hanford Tank 241-C-106: Residual Waste Contaminant Release Model and Supporting Data (open access)

Hanford Tank 241-C-106: Residual Waste Contaminant Release Model and Supporting Data

This report was revised in May 2007 to correct values in Section 3.4.1.7, second paragraph, last sentence; 90Sr values in Tables 3.22 and 3.32; and 99Tc values Table 4.3 and in Chapter 5. In addition, the tables in Appendix F were updated to reflect corrections to the 90Sr values. The rest of the text remains unchanged from the original report issued in May 2005. CH2M HILL is producing risk/performance assessments to support the closure of single-shell tanks at the DOE's Hanford Site. As part of this effort, staff at PNNL were asked to develop release models for contam¬inants of concern that are present in residual sludge remaining in tank 241-C-106 (C-106) after final retrieval of waste from the tank. This report provides the information developed by PNNL.
Date: May 23, 2007
Creator: Deutsch, William J.; Krupka, Kenneth M.; Lindberg, Michael J.; Cantrell, Kirk J.; Brown, Christopher F. & Schaef, Herbert T.
Object Type: Report
System: The UNT Digital Library