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Insertion Devices R and Ds for NSLS-II (open access)

Insertion Devices R and Ds for NSLS-II

NSLS-II is a medium energy storage ring of 3GeV electron beam energy with sub-nm.rad horizontal emittance and top-off capability at 500mA. Damping wigglers will be used not only to reduce the beam emittance but also for broadband sources for users. Cryo-Permanent Magnet Undulators (CPMUs) are considered for hard X-ray linear device, and permanent magnet based Elliptically Polarized Undulators (EPUs) are for polarization control. Rigorous R&D plans have been established to pursue the performance enhancement of the above devices as well as building new types of insertion devices such as high temperature superconducting wiggler/undulators. This paper describes the details of these activities and discuss technical issues.
Date: June 25, 2007
Creator: Tanabe, T.; Harder, D. A.; Rakowsky, G.; Shaftan, T. & Skaritka, J.
System: The UNT Digital Library
A High-resolution TOF Detector - A Possible Way to Compete with a RICH Detector (open access)

A High-resolution TOF Detector - A Possible Way to Compete with a RICH Detector

Using two identical 64-pixel Burle/Photonis MCP-PMTs to provide start and stop signals, they have achieved a timing resolution of {sigma}{sub Single{_}detector} {approx} 7.2 ps for N{sub pe} {approx} 50 photoelectrons (N{sub pe}) with a laser diode providing a 1 mm spot on the MCP window. The limiting resolution achieved was {sigma}{sub Single{_}detector} {approx} 5.0 ps for N{sub pe} {approx} 180, for which they estimate the MCP-PMT contribution of {sigma}{sub MCP-PMT} {approx} 4.5 ps. The electronics contribution is estimated as {sigma}{sub Electrons} = 3.42 ps. These results suggest that an ultra-high resolution TOF detector may become a reality at future experiments one day.
Date: July 25, 2008
Creator: Va'vra, J; Ertley, C.; Leith, D. W. G. S.; Ratcliff, B. & Schwiening, J.
System: The UNT Digital Library
A phylogenomic gene cluster resource: The phylogeneticallyinferred groups (PhlGs) database (open access)

A phylogenomic gene cluster resource: The phylogeneticallyinferred groups (PhlGs) database

We present here the PhIGs database, a phylogenomic resource for sequenced genomes. Although many methods exist for clustering gene families, very few attempt to create truly orthologous clusters sharing descent from a single ancestral gene across a range of evolutionary depths. Although these non-phylogenetic gene family clusters have been used broadly for gene annotation, errors are known to be introduced by the artifactual association of slowly evolving paralogs and lack of annotation for those more rapidly evolving. A full phylogenetic framework is necessary for accurate inference of function and for many studies that address pattern and mechanism of the evolution of the genome. The automated generation of evolutionary gene clusters, creation of gene trees, determination of orthology and paralogy relationships, and the correlation of this information with gene annotations, expression information, and genomic context is an important resource to the scientific community.
Date: August 25, 2005
Creator: Dehal, Paramvir S. & Boore, Jeffrey L.
System: The UNT Digital Library
IBS suppression lattice in RHIC: theory and experimental verification (open access)

IBS suppression lattice in RHIC: theory and experimental verification

Intra-beam scattering (IBS) is the limiting factor of the luminosity lifetime for Relativistic Heavy Ion Collider (RHIC) operation with heavy ions. Over the last few years the process of IBS was carefully studied in RHIC with dedicated IBS measurements and their comparison with the theoretical models. A new lattice was recently designed and implemented in RHIC to suppress transverse IBS growth, which lowered the average arc dispersion by about 20% [1]. This lattice became operational during RHIC Run-8. We review the IBS suppression mechanism, IBS measurements before and after the lattice change, and comparisons with predictions.
Date: August 25, 2008
Creator: Fedotov, A. V.; Bai, M.; Bruno, D.; Cameron, P.; Connolly, R.; Cupolo, J. et al.
System: The UNT Digital Library
Ab initio Molecular Dynamics Simulations of Water Under Static and Shock Compressed Conditions (open access)

Ab initio Molecular Dynamics Simulations of Water Under Static and Shock Compressed Conditions

We report herein a series of ab initio simulations of water under both static and shocked conditions. We have calculated the coherent x-ray scattering intensity of several phases of water under high pressure, using ab initio Density Functional Theory (DFT). We provide new atomic scattering form factors for water at extreme conditions, which take into account frequently neglected changes in ionic charge and electron delocalization. We have also simulated liquid water undergoing shock loading of velocities from 5-11 km/s using the Multi-Scale Shock Technique (MSST). We show that Density Functional Theory (DFT) molecular dynamics results compare extremely well to experiments on the water shock Hugoniot.
Date: July 25, 2007
Creator: Goldman, N; Fried, L E; Mundy, C J; Kuo, I W; Curioni, A & Reed, E
System: The UNT Digital Library
SIGNIFICANT PROGRESS IN THE DEPLOYMENT OF NEW TECHNOLOGIES FOR THE RETRIEVAL OF HANFORD RADIOACTIVE WASTE STORAGE TANKS (open access)

SIGNIFICANT PROGRESS IN THE DEPLOYMENT OF NEW TECHNOLOGIES FOR THE RETRIEVAL OF HANFORD RADIOACTIVE WASTE STORAGE TANKS

None
Date: February 25, 2008
Creator: RE, RAYMOND; RA, DODD; KE, CARPENTER & MH, STURGES
System: The UNT Digital Library
Design and Implementation of a Facility for Discovering New Scintillator Materials (open access)

Design and Implementation of a Facility for Discovering New Scintillator Materials

We describe the design and operation of a high-throughput facility for synthesizing thousands of inorganic crystalline samples per year and evaluating them as potential scintillation detector materials. This facility includes a robotic dispenser, arrays of automated furnaces, a dual-beam X-ray generator for diffractometery and luminescence spectroscopy, a pulsed X-ray generator for time response measurements, computer-controlled sample changers, an optical spectrometer, and a network-accessible database management system that captures all synthesis and measurement data.
Date: April 25, 2008
Creator: Derenzo, Stephen; Derenzo, Stephen E; Boswell, Martin S.; Bourret-Courchesne, Edith; Boutchko, Rostyslav; Budinger, Thomas F. et al.
System: The UNT Digital Library
Error Estimates Derived from the Data for Least-Squares Spline Fitting (open access)

Error Estimates Derived from the Data for Least-Squares Spline Fitting

The use of least-squares fitting by cubic splines for the purpose of noise reduction in measured data is studied. Splines with variable mesh size are considered. The error, the difference between the input signal and its estimate, is divided into two sources: the R-error, which depends only on the noise and increases with decreasing mesh size, and the Ferror, which depends only on the signal and decreases with decreasing mesh size. The estimation of both errors as a function of time is demonstrated. The R-error estimation requires knowledge of the statistics of the noise and uses well-known methods. The primary contribution of the paper is a method for estimating the F-error that requires no prior knowledge of the signal except that it has four derivatives. It is calculated from the difference between two different spline fits to the data and is illustrated with Monte Carlo simulations and with an example.
Date: June 25, 2007
Creator: Blair, Jerome
System: The UNT Digital Library
Multiplicative or t1 Noise in NMR Spectroscopy (open access)

Multiplicative or t1 Noise in NMR Spectroscopy

The signal in an NMR experiment is highly sensitive to fluctuations of the environment of the sample. If, for example, the static magnetic field B{sub 0}, the amplitude and phase of radio frequency (rf) pulses, or the resonant frequency of the detection circuit are not perfectly stable and reproducible, the magnetic moment of the spins is altered and becomes a noisy quantity itself. This kind of noise not only depends on the presence of a signal, it is in fact proportional to it. Since all the spins at a particular location in a sample experience the same environment at any given time, this noise primarily affects the reproducibility of an experiment, which is mainly of importance in the indirect dimensions of a multidimensional experiment, when intense lines are suppressed with a phase cycle, or for difference spectroscopy techniques. Equivalently, experiments which are known to be problematic with regard to their reproducibility, like flow experiments or experiments with a mobile target, tend to be affected stronger by multiplicative noise. In this article it is demonstrated how multiplicative noise can be identified and characterized using very simple, repetitive experiments. An error estimation approach is developed to give an intuitive, yet quantitative understanding …
Date: January 25, 2005
Creator: Granwehr, Josef
System: The UNT Digital Library
PEP-II Status (open access)

PEP-II Status

PEP-II and BaBar have just finished run 7, the last run of the SLAC B-factory. PEP-II was one of the few high-current e+e- colliding accelerators and holds the present world record for stored electrons and stored positrons. It has stored 2.07 A of electrons, nearly 3 times the design current of 0.75 A and it has stored 3.21 A of positrons, 1.5 times more than the design current of 2.14 A. High-current beams require careful design of several systems. The feedback systems that control instabilities, the RF system stability loops, and especially the vacuum systems have to handle the higher power demands. We present here some of the accomplishments of the PEP-II accelerator and some of the problems we encountered while running high-current beams.
Date: July 25, 2008
Creator: Sullivan, M.; Bertsche, K.; Browne, M.; Cai, Y.; Cheng, W.; Colocho, W. et al.
System: The UNT Digital Library
Climate Forcings and Climate Sensitivities Diagnosed from Coupled Climate Model Integrations (open access)

Climate Forcings and Climate Sensitivities Diagnosed from Coupled Climate Model Integrations

A simple technique is proposed for calculating global mean climate forcing from transient integrations of coupled Atmosphere Ocean General Circulation Models (AOGCMs). This 'climate forcing' differs from the conventionally defined radiative forcing as it includes semi-direct effects that account for certain short timescale responses in the troposphere. Firstly, we calculate a climate feedback term from reported values of 2 x CO{sub 2} radiative forcing and surface temperature time series from 70-year simulations by twenty AOGCMs. In these simulations carbon dioxide is increased by 1%/year. The derived climate feedback agrees well with values that we diagnose from equilibrium climate change experiments of slab-ocean versions of the same models. These climate feedback terms are associated with the fast, quasi-linear response of lapse rate, clouds, water vapor and albedo to global surface temperature changes. The importance of the feedbacks is gauged by their impact on the radiative fluxes at the top of the atmosphere. We find partial compensation between longwave and shortwave feedback terms that lessens the inter-model differences in the equilibrium climate sensitivity. There is also some indication that the AOGCMs overestimate the strength of the positive longwave feedback. These feedback terms are then used to infer the shortwave and longwave time …
Date: July 25, 2006
Creator: de F. Forster, Piers & Taylor, Karl E.
System: The UNT Digital Library
Gamma-ray Albedo of Small Solar System Bodies (open access)

Gamma-ray Albedo of Small Solar System Bodies

We calculate the {gamma}-ray albedo flux from cosmic-ray (CR) interactions with the solid rock and ice in Main Belt asteroids and Kuiper Belt objects (KBOs) using the Moon as a template. We show that the {gamma}-ray albedo for the Main Belt and KBOs strongly depends on the small-body mass spectrum of each system and may be detectable by the forthcoming Gamma Ray Large Area Space Telescope (GLAST). If detected, it can be used to derive the mass spectrum of small bodies in the Main Belt and Kuiper Belt and to probe the spectrum of CR nuclei at close-to-interstellar conditions. The orbits of the Main Belt asteroids and KBOs are distributed near the ecliptic, which passes through the Galactic center and high Galactic latitudes. Therefore, the {gamma}-ray emission by the Main Belt and Kuiper Belt has to be taken into account when analyzing weak {gamma}-ray sources close to the ecliptic. The asteroid albedo spectrum also exhibits a 511 keV line due to secondary positrons annihilating in the rock. This may be an important and previously unrecognized celestial foreground for the INTErnational Gamma-Ray Astrophysics Laboratory (INTEGRAL) observations of the Galactic 511 keV line emission including the direction of the Galactic center. For …
Date: March 25, 2008
Creator: Moskalenko, I.V.
System: The UNT Digital Library
The Gamma-Ray Albedo of the Moon (open access)

The Gamma-Ray Albedo of the Moon

We use the GEANT4 Monte Carlo framework to calculate the {gamma}-ray albedo of the Moon due to interactions of cosmic ray (CR) nuclei with moon rock. Our calculation of the albedo spectrum agrees with the EGRET data. We show that the spectrum of {gamma}-rays from the Moon is very steep with an effective cutoff around 3-4 GeV (600 MeV for the inner part of the Moon disk) and exhibits a narrow pion-decay line at 67.5 MeV, perhaps unique in astrophysics. Apart from other astrophysical sources, the albedo spectrum of the Moon is well understood, including its absolute normalization; this makes it a useful 'standard candle' for {gamma}-ray telescopes. The steep albedo spectrum also provides a unique opportunity for energy calibration of {gamma}-ray telescopes, such as the forthcoming Gamma Ray Large Area Space Telescope (GLAST). Since the albedo flux depends on the incident CR spectrum which changes over the solar cycle, it is possible to monitor the CR spectrum using the albedo {gamma}-ray flux. Simultaneous measurements of CR proton and helium spectra by the Payload for Antimatter-Matter Exploration and Light-nuclei Astrophysics (PAMELA), and observations of the albedo {gamma}-rays by the GLAST Large Area Telescope (LAT), can be used to test the …
Date: March 25, 2008
Creator: Moskalenko, I.V.; /Stanford U., HEPL /KIPAC, Menlo Park; Porter, T.A. & /UC, Santa Cruz
System: The UNT Digital Library
First-Year Spectroscopy for the SDSS-II Supernova Survey (open access)

First-Year Spectroscopy for the SDSS-II Supernova Survey

This paper presents spectroscopy of supernovae discovered in the first season of the Sloan Digital Sky Survey-II Supernova Survey. This program searches for and measures multi-band light curves of supernovae in the redshift range z = 0.05-0.4, complementing existing surveys at lower and higher redshifts. Our goal is to better characterize the supernova population, with a particular focus on SNe Ia, improving their utility as cosmological distance indicators and as probes of dark energy. Our supernova spectroscopy program features rapid-response observations using telescopes of a range of apertures, and provides confirmation of the supernova and host-galaxy types as well as precise redshifts. We describe here the target identification and prioritization, data reduction, redshift measurement, and classification of 129 SNe Ia, 16 spectroscopically probable SNe Ia, 7 SNe Ib/c, and 11 SNe II from the first season. We also describe our efforts to measure and remove the substantial host galaxy contamination existing in the majority of our SN spectra.
Date: March 25, 2008
Creator: Zheng, Chen; Romani, Roger W.; Sako, Masao; Marriner, John; Bassett, Bruce; Becker, Andrew et al.
System: The UNT Digital Library
High Performance Ebis for Rhic. (open access)

High Performance Ebis for Rhic.

An Electron Beam Ion Source (EBIS), capable of producing high charge states and high beam currents of any heavy ion species in short pulses, is ideally suited for injection into a synchrotron. An EBIS-based, high current, heavy ion preinjector is now being built at Brookhaven to provide increased capabilities for the Relativistic Heavy Ion Collider (RHIC), and the NASA Space Radiation Laboratory (NSRL). Benefits of the new preinjector include the ability to produce ions of any species, fast switching between species to serve the simultaneous needs of multiple programs, and lower operating and maintenance costs. A state-of-the-art EBIS, operating with an electron beam current of up to 10 A, and producing multi-milliamperes of high charge state heavy ions, has been developed at Brookhaven, and has been operating very successfully on a test bench for several years. The present performance of this high-current EBIS is presented, along with details of the design of the scaled-up EBIS for RHIC, and the status of its construction. Other aspects of the project, including design and construction of the heavy ion RFQ, Linac, and matching beamlines, are also mentioned.
Date: June 25, 2007
Creator: Alessi, J.; Beebe, E.; Gould, O.; Kponou, A.; Lockey, R.; Pikin, A. et al.
System: The UNT Digital Library
Electron Cyclotron Resonances in Electron Cloud Dynamics (open access)

Electron Cyclotron Resonances in Electron Cloud Dynamics

We report a previously unknown resonance for electron cloud dynamics. The 2D simulation code"POSINST" was used to study the electron cloud buildup at different z positions in the International Linear Collider positron damping ring wiggler. An electron equilibrium density enhancement of up to a factor of 3 was found at magnetic field values for which the bunch frequency is an integral multiple of the electron cyclotron frequency. At low magnetic fields the effects of the resonance are prominent, but when B exceeds ~;;(2 pi mec/(elb)), with lb = bunch length, effects of the resonance disappear. Thus short bunches and low B fields are required for observing the effect. The reason for the B field dependence, an explanation of the dynamics, and the results of the 2D simulations and of a single-particle tracking code used to elucidate details of the dynamics are discussed.
Date: June 25, 2008
Creator: Celata, Christine; Celata, C. M.; Furman, Miguel A.; Vay, J. L. & Yu, Jennifer W.
System: The UNT Digital Library
DEVELOPMENT OF A ROTARY MICROFILTER FOR RADIOACTIVE WASTE APPLICATIONS (open access)

DEVELOPMENT OF A ROTARY MICROFILTER FOR RADIOACTIVE WASTE APPLICATIONS

The processing rate of Savannah River Site (SRS) high-level waste decontamination processes are limited by the flow rate of the solid-liquid separation. The baseline process, using a 0.1 micron cross-flow filter, produces {approx}0.02 gpm/sq. ft. of filtrate under expected operating conditions. Savannah River National Laboratory (SRNL) demonstrated significantly higher filter flux for actual waste samples using a small-scale rotary filter. With funding from the U. S. Department of Energy Office of Cleanup Technology, SRNL personnel are evaluating and developing the rotary microfilter for radioactive service at SRS. The authors improved the design for the disks and filter unit to make them suitable for high-level radioactive service. They procured two units using the new design, tested them with simulated SRS wastes, and evaluated the operation of the units. Work to date provides the following conclusions and program status: (1) The authors modified the design of the filter disks to remove epoxy and Ryton{reg_sign}. The new design includes welding both stainless steel and ceramic coated stainless steel filter media to a stainless steel support plate. The welded disks were tested in the full-scale unit. They showed good reliability and met filtrate quality requirements. (2) The authors modified the design of the unit, …
Date: February 25, 2008
Creator: Poirier, M; David Herman, D & Samuel Fink, S
System: The UNT Digital Library
Interface reconstruction and sub-zone physics models (open access)

Interface reconstruction and sub-zone physics models

None
Date: August 25, 2005
Creator: Bailey, D S; Brown, S A & Zimmerman, G B
System: The UNT Digital Library
SLIM--An Early Work Revisited (open access)

SLIM--An Early Work Revisited

An early, but at the time illuminating, piece of work on how to deal with a general, linearly coupled accelerator lattice is revisited. This work is based on the SLIM formalism developed in 1979-1981.
Date: July 25, 2008
Creator: Chao, Alex
System: The UNT Digital Library
Investigation of Tractor Base Bleeding for Heavy Vehicle Aerodynamic Drag Reduction (open access)

Investigation of Tractor Base Bleeding for Heavy Vehicle Aerodynamic Drag Reduction

One of the main contributors to the aerodynamic drag of a heavy vehicle is tractor-trailer gap drag, which arises when the vehicle operates within a crosswind. Under this operating condition, freestream flow is entrained into the tractor-trailer gap, imparting a momentum exchange to the vehicle and subsequently increasing the aerodynamic drag. While a number of add-on devices, including side extenders, splitter plates, vortex stabilizers, and gap sealers, have been previously tested to alleviate this source of drag, side extenders remain the primary add-on device of choice for reducing tractor-trailer gap drag. However, side extenders are not without maintenance and operational issues. When a heavy vehicle pivots sharply with respect to the trailer, as can occur during loading or unloading operations, the side extenders can become crushed against the trailer. Consequently, fleet operators are forced to incur additional costs to cover the repair or replacement of the damaged side extenders. This issue can be overcome by either shortening the side extenders or by devising an alternative drag reduction concept that can perform just as effectively as side extenders. To explore such a concept, we investigate tractor base bleeding as a means of reducing gap drag. Wind tunnel measurements are made on …
Date: October 25, 2007
Creator: Ortega, J; Salari, K & Storms, B
System: The UNT Digital Library
Evaluating Fenestration Products for Zero-Energy Buildings: Issuesfor Discussion (open access)

Evaluating Fenestration Products for Zero-Energy Buildings: Issuesfor Discussion

Computer modeling to determine fenestration product energy properties (U-factor, SHGC, VT) has emerged as the most cost-effective and accurate means to quantify them. Fenestration product simulation tools have been effective in increasing the use of low-e coatings and gas fills in insulating glass and in the widespread use of insulating frame designs and materials. However, for more efficient fenestration products (low heat loss products, dynamic products, products with non-specular optical characteristics, light re-directing products) to achieve widespread use, fenestration modeling software needs to be improved. This paper addresses the following questions: (1) Are the current properties (U, SHGC, VT) calculated sufficient to compare and distinguish between windows suitable for Zero Energy Buildings and conventional window products? If not, what data on the thermal and optical performance, on comfort, and on peak demand of windows is needed. (2) Are the algorithms in the tools sufficient to model the thermal and optical processes? Are specific heat transfer and optical effects not accounted for? Is the existing level of accuracy enough to distinguish between products designed for Zero Energy Buildings? Is the current input data adequate?
Date: July 25, 2006
Creator: Arasteh, Dariush; Curcija, Charlie; Huang, Joe; Huizenga,Charlie & Kohler, Christian
System: The UNT Digital Library
Design Studies of Magnet Systems for Muon Helical Cooling Channels (open access)

Design Studies of Magnet Systems for Muon Helical Cooling Channels

Helical cooling channels with superimposed solenoid and helical dipole and quadrupole coils, and a pressurized gas absorber in the aperture offer high efficiency of 6D muon beam cooling. In this paper, we continue design studies and comparison of two basic concepts of magnet system proposed for a helical cooling channel focusing on the high field sections. The results of magnetic analysis and Lorentz force calculations as well as the superconductor choice are presented and discussed.
Date: June 25, 2008
Creator: Kashikhin, V.; Kashikhin, V. S.; Lamm, M. J.; Lopes, M. L.; Zlobin, A. V.; Alsharo'a, M. et al.
System: The UNT Digital Library
Test Results of a Nb3Sn Wind/React 'Stress-Managed' BlockDipole (open access)

Test Results of a Nb3Sn Wind/React 'Stress-Managed' BlockDipole

A second phase of a highfield dipole technology developmenthas been tested. A Nb3Sn block-coil model dipole was fabricated, usingmagnetic mirror geometry and wind/react coil technology. The primaryobjective of this phase was to make a first experimental test of thestress-management strategy pioneered at Texas A&M. In this strategy ahigh-strength support matrix is integrated with the windings to interceptLorentz stress from the inner winding so that it does not accumulate inthe outer winding. The magnet attained a field that was consistent withshort sample limit on the first quench; there was no training. Thedecoupling of Lorentz stress between inner and outer windings wasvalidated. In ramp rate studies the magnet exhibited a remarkablerobustness in rapid ramping operation. It reached 85 percent of shortsample(ss) current even while ramping 2-3 T/s. This robustness isattributed to the orientation of the Rutherford cables parallel to thefield in the windings, instead of the transverse orientation thatcharacterizes common dipole designs. Test results are presented and thenext development phase plans are discussed.
Date: August 25, 2006
Creator: McInturff, A.; Bish, P.; Blackburn, R.; Diaczenko, N.; Elliott,T.; Hafalia Jr., R. et al.
System: The UNT Digital Library
A Survey of Hadron Therapy Accelerator Technologies. (open access)

A Survey of Hadron Therapy Accelerator Technologies.

Hadron therapy has entered a new age [1]. The number of facilities grows steadily, and 'consumer' interest is high. Some groups are working on new accelerator technology, while others optimize existing designs by reducing capital and operating costs, and improving performance. This paper surveys the current requirements and directions in accelerator technology for hadron therapy.
Date: June 25, 2007
Creator: Peggs, S.; Satogata, T. & Flanz, J.
System: The UNT Digital Library