Discovery of Pulsed Gamma Rays from the Young Radio Pulsar PSR J1028-5819 with the Fermi Large Area Telescope (open access)

Discovery of Pulsed Gamma Rays from the Young Radio Pulsar PSR J1028-5819 with the Fermi Large Area Telescope

Radio pulsar PSR J1028-5819 was recently discovered in a high-frequency search (at 3.1 GHz) in the error circle of the Energetic Gamma-Ray Experiment Telescope (EGRET) source 3EG J1027-5817. The spin-down power of this young pulsar is great enough to make it very likely the counterpart for the EGRET source. We report here the discovery of {gamma}-ray pulsations from PSR J1028-5819 in early observations by the Large Area Telescope (LAT) on the Fermi Gamma-Ray Space Telescope. The {gamma}-ray light curve shows two sharp peaks having phase separation of 0.460 {+-} 0.004, trailing the very narrow radio pulse by 0.200 {+-} 0.003 in phase, very similar to that of other known {gamma}-ray pulsars. The measured {gamma}-ray flux gives an efficiency for the pulsar of {approx}10-20% (for outer magnetosphere beam models). No evidence of a surrounding pulsar wind nebula is seen in the current Fermi data but limits on associated emission are weak because the source lies in a crowded region with high background emission. However, the improved angular resolution afforded by the LAT enables the disentanglement of the previous COS-B and EGRET source detections into at least two distinct sources, one of which is now identified as PSR J1028-5819.
Date: May 15, 2009
Creator: Abdo, Aous A.; Ackermann, M.; Atwood, W.B.; Baldini, L.; Ballet, J.; Barbiellini, Guido et al.
System: The UNT Digital Library
Advances in full field microscopy with table-top soft x-ray lasers (open access)

Advances in full field microscopy with table-top soft x-ray lasers

We describe recent advances in the demonstration of table-top full field microscopes that use soft x-ray lasers for illumination. We have achieved wavelength resolution and single shot exposure operation with a very compact 46.9 nm microscope based on a desk-top size capillary discharge laser. This {lambda}-46.9 nm microscope has been used to capture full field images of a variety of nanostructure systems and surfaces. In a separate development we have demonstrated a zone plate microscope that uses {lambda}=13.2 nm laser illumination to image absorption defects in an extreme ultraviolet lithography (EUVL) mask in the same geometry used in a 4x demagnification EUVL stepper. Characterization of the microscope’s transfer function shows it can resolve 55 nm half period patterns. With these capabilities, the {lambda}-13.2 nm microscope is well suited for evaluation of pattern and defect printability of EUVL masks for the 22 nm node.
Date: May 18, 2009
Creator: Menoni, C. S.; Brizuela, F.; Wang, Y.; Brewer, C. A.; Luther, B. M.; Pedaci, F. et al.
System: The UNT Digital Library
Simulations of Electron-Cloud Current Density Measurements in Dipoles, Drifts And Wigglers at CesrTA (open access)

Simulations of Electron-Cloud Current Density Measurements in Dipoles, Drifts And Wigglers at CesrTA

A core component of the CesrTA research program at Cornell is to fully understand the electron cloud effect through the use of simulation programs that have been developed to predict the growth of the cloud and its interaction with the beam. As a local probe of the electron cloud, several segmented retarding field analyzers (RFAs) have been installed in CesrTA in dipole, drift and wiggler regions. Using these RFAs, the energy spectrum of the time-average electron cloud current density striking the walls has been measured for a variety of bunch train patterns, with different bunch currents, beam energies, emittances, and bunch lengths, and for both positron and electron beams. This paper will compare these measurements with the predictions of simulation programs.
Date: May 4, 2009
Creator: Calvey, J.; Crittenden, J. A.; Dugan, G.; Greenwald, S.; Livezey, J. A.; Palmer, M. A. et al.
System: The UNT Digital Library
CSR Interaction for a 2D Energy-Chirped Bunch on a General Orbit (open access)

CSR Interaction for a 2D Energy-Chirped Bunch on a General Orbit

When an electron bunch with initial linear energy chirp traverses a bunch compression chicane, the bunch interacts with itself via coherent synchrotron radiation (CSR) and space charge force. The effective longitudinal CSR force for such kind of 2D bunch on a circular orbit has been analyzed earlier [1]. In this paper, we present the analytical results of the effective longitudinal CSR force for a 2D energy-chirped bunch going through a general orbit, which includes the entrance and exit of a circular orbit. In particular, we will show the behavior of the force in the last bend of a chicane when the bunch is under extreme compression. This is the condition when bifurcation of bunch phase space occurs in many CSR measurements. [1] R. Li, Phys. Rev. ST Accel. Beams 11, 024401 (2008)
Date: May 1, 2009
Creator: Li, Rui
System: The UNT Digital Library
Recent Progress on Design Studies of High-Luminosity Ring-Ring Electron-Ion Collider at CEBAF (open access)

Recent Progress on Design Studies of High-Luminosity Ring-Ring Electron-Ion Collider at CEBAF

The conceptual design of a ring-ring electron-ion collider based on CEBAF has been continuously optimized to cover a wide center-of-mass energy region and to achieve high luminosity and polarization to support next generation nuclear science programs. Here, we summarize the recent design improvements and R&D progress on interaction region optics with chromatic aberration compensation, matching and tracking of electron polarization in the Figure-8 ring, beam-beam simulations and ion beam cooling studies.
Date: May 1, 2009
Creator: Zhang, Y.; Bruell, A.; Chevtsov, P.; Derbenev, Y. S.; Ent, R.; Krafft, G. A. et al.
System: The UNT Digital Library
Design of Superconducting Parallel Bar Deflecting and Crabbing rf Structures (open access)

Design of Superconducting Parallel Bar Deflecting and Crabbing rf Structures

A new concept for a deflecting and crabbing rf structure based on half-wave resonant lines was introduced recently*. It offers significant advantages to existing designs and, because of it compactness, allows low frequency operation. This concept has been further refined and optimized for superconducting implementation. Results of this optimization and application to a 400 MHz crabbing cavity and a 499 MHz deflecting cavity are presented.
Date: May 1, 2009
Creator: Jean Delayen, Haipeng Wang
System: The UNT Digital Library
Surface Topography of 'Hotspot' Regions from a Single Cell SRF Cavity (open access)

Surface Topography of 'Hotspot' Regions from a Single Cell SRF Cavity

Performance of SRF cavities are limited by non-linear localized effects. The variation of local material characters between "hot" and "cold" spots is thus of intense interest. Such locations were identified in a BCP-etched large-grain single-cell cavity and removed for examination by high resolution electron microscopy (SEM), electron-back scattering diffraction microscopy (EBSD), optical microscopy, and 3D profilometry. Pits with clearly discernable crystal facets were observed in both "hotspot" and "coldspot" specimens. The pits were found in-grain, at bi-crystal boundaries, and on tri-crystal junctions. They are interpreted as etch pits induced by surface crystal defects (e.g. dislocations). All "coldspots" examined had qualitatively low density of etching pits or very shallow tri-crystal boundary junction. EBSD revealed the crystal structure surrounding the pits via crystal phase orientation mapping, while 3D profilometry gave information on the depth and size of the pits. In addition, a survey of the samples by energy dispersive X-ray analysis (EDX) did not show any significant contamination of the samples surface.
Date: May 1, 2009
Creator: Xin Zhao, Gianluigi Ciovati, Charles Reece, Andy Wu
System: The UNT Digital Library
Task 2: Materials for Advanced Boiler and Oxy-combustion Systems (open access)

Task 2: Materials for Advanced Boiler and Oxy-combustion Systems

Characterize advanced boiler (oxy-fuel combustion, biomass cofired) gas compositions and ash deposits Generate critical data on the effects of environmental conditions; develop a unified test method with a view to future standardisation
Date: May 1, 2009
Creator: Holcomb, G. R. & McGhee, B.
System: The UNT Digital Library
Design and Measurement of the NSLS II Correctors (open access)

Design and Measurement of the NSLS II Correctors

The National Synchrotron Light Source II (NSLS-II) under construction at Brookhaven National Laboratory will be a new state-of-the-art 3 Gev electron storage ring designed to deliver world-leading intensity and brightness, and will produce x-rays more than 10,000 times brighter than the current NSLS at Brookhaven. The 792-meter circumference storage ring is comprised of approximately 1000 magnetic elements, 300 of which are discrete corrector magnets. The three variants are: 120 of the 100 mm aperture correctors, 60 of the 156 mm aperture correctors, and 90 of the air core correctors.[1] The 100 mm and 156 mm horizontal and vertical dipole correctors come in two varieties: with and without a DC skew quad corrector. The air core is strictly an AC horizontal and vertical dipole corrector. The specifications are listed. Discrete corrector magnets are used for the 230 horizontal and vertical steering magnets in the NSLS-II storage ring. A unique design incorporates both dipole and skew quad correctors for (DC) steering in the same magnet. Separate AC (orbit feedback) correctors have also been designed. Comparison with alternate designs are presented as well as prototype measurements.
Date: May 4, 2009
Creator: Spataro, C.; Danby, G.; Jackson, J.W.; Jain, A.K.; Rehak, M.; Singh, O. et al.
System: The UNT Digital Library
Photodiode-Based X-Ray Beam-Position Monitor With High Spatial-Resolution for the NSLS-II Beamlines (open access)

Photodiode-Based X-Ray Beam-Position Monitor With High Spatial-Resolution for the NSLS-II Beamlines

We developed a photodiode-based monochromatic X-ray beam-position monitor (X-BPM) with high spatial resolution for the project beamlines of the NSLS-II. A ring array of 32 Si PIN-junction photodiodes were designed for use as a position sensor, and a low-noise HERMES4 ASIC chip was integrated into the electronic readout system. A series of precision measurements to characterize electrically the Si-photodiode sensor and the ASIC chip demonstrated that the inherent noise is sufficiently below tolerance levels. Following up modeling of detector's performance, including geometrical optimization using a Gaussian beam, we fabricated and assembled a first prototype. In this paper, we describe the development of this new state-of-the-art X-ray BPM along the beamline, in particular, downstream from the monochromator.
Date: May 25, 2009
Creator: Yoon, P.S. & Siddons, D. P.
System: The UNT Digital Library
Complete genome sequence of Dyadobacter fermentans type strain (NS114T) (open access)

Complete genome sequence of Dyadobacter fermentans type strain (NS114T)

Dyadobacter fermentans (Chelius MK and Triplett EW, 2000) is the type species of the genus Dyadobacter. It is of phylogenetic interest because of its location in the Cytophagaceae, a very diverse family within the order 'Sphingobacteriales'. D. fermentans has a mainly respiratory metabolism, stains Gram-negative, is non-motile and oxidase and catalase positive. It is characterized by the production of cell filaments in ageing cultures, a flexirubin-like pigment and its ability to ferment glucose, which is almost unique in the aerobically living members of this taxonomically difficult family. Here we describe the features of this organism, together with the complete genome sequence, and annotation. This is the first complete genome sequence of the 'sphingobacterial' genus Dyadobacter, and this 6,967,790 bp long single replicon genome with its 5804 protein-coding and 50 RNA genes is part of the Genomic Encyclopedia of Bacteria and Archaea project.
Date: May 20, 2009
Creator: Lang, Elke; Lapidus, Alla; Chertkov, Olga; Brettin, Thomas; Detter, John C.; Han, Cliff et al.
System: The UNT Digital Library
FFAG Designs for the International Design Study for the Neutrino Factory (open access)

FFAG Designs for the International Design Study for the Neutrino Factory

The International Design Study for the Neutrino Factory (IDS-NF) aims to produce a design report for a neutrino factory. One component of that design is a linear nonscaling fixed-field alternating gradient accelerator (FFAG) that will accelerate to the final energy of 25 GeV. An FFAG is used to reduce the machine cost by maximizing the number of passes made through the RF cavities. We present some design options for this FFAG, individually optimized for cost. We study the addition of nonlinear magnets to the lattice to improve the performance of the lattice and consider the negative effects of doing so.
Date: May 4, 2009
Creator: Berg, J. S. & Machida, S.
System: The UNT Digital Library
Stability Issues of the Mu2e Proton Beam (open access)

Stability Issues of the Mu2e Proton Beam

Stability issues of the mu2e proton beam are discussed. These include space-charge distortion of bunch shape, microwave instabilities, mode-coupling instabilities, head-tail instabilities, as well as electron-cloud effects. We have studied several beam stability issues of the proton beam heading to the target for the mu2e experiment. We find bunch-shape distortions driven by the space charge force is reasonably small, and longitudinal microwave instability will unlikely to occur. Electron-cloud buildup, with density up to {rho}{sub e} {approx} 2 x 10{sup 12} m{sup -3} in the Accumulator, can probably drive head-tail instabilities. However, these, together with the instabilities driven by the resistive-wall impedance can be avoided by restricting the chromaticity to larger than {approx} 0.2. TMCI will not occur even when the electron-cloud wake is included.
Date: May 1, 2009
Creator: Ng, King-Yuen
System: The UNT Digital Library
RHIC low energy tests and initial operations (open access)

RHIC low energy tests and initial operations

Future Relativistic Heavy Ion Collider (RHIC) runs, including a portion of FY10 heavy ion operations, will explore collisions at center of mass energies of 5-50 GeV/n (GeV/nucleon). Operations at these energies is motivated by a search for the QCD phase transition critical point. The lowest end of this energy range is nearly a factor of four below the nominal RHIC injection center of mass energy of {radical} s = 20.8 GeV/n. There are several operational challenges in the RHIC low-energy regime, including harmonic number changes, small longitudinal acceptance, lowered magnet field quality, nonlinear orbit control, and luminosity monitoring. We report on the experience with some of these challenges during beam tests with gold in March 2008, including first RHIC operations at {radical}s = 9.18 GeV/n and first beam experience at {radical}s = 5 GeV/n.
Date: May 4, 2009
Creator: Satogata, T.; Ahrens, L.; Bai, M.; Brennan, J. M.; Bruno, D.; Butler, J. et al.
System: The UNT Digital Library
Timing Jitter Characterization at the NSLS SDL (open access)

Timing Jitter Characterization at the NSLS SDL

Two novel timing jitter measurement techniques with a 100 fs resolution are presented in this paper. The first technique based on the Schottky effect, is used to measure the timing jitter between the photoinjector drive laser and the RF system; and it was employed to characterize the environment effects on the timing jitter. The I/Q beam monitor based on a stripline beam position monitor (BPM) is used to characterize the electron beam arrival time jitter.
Date: May 4, 2009
Creator: Qian,H.; Hidaka, Y.; Murphy, J. B.; Podobedov, B.; Seletskiy, Shen, Y.; Yang, X. et al.
System: The UNT Digital Library
Linear Algebraic Method for Non-Linear Map Analysis (open access)

Linear Algebraic Method for Non-Linear Map Analysis

We present a newly developed method to analyze some non-linear dynamics problems such as the Henon map using a matrix analysis method from linear algebra. Choosing the Henon map as an example, we analyze the spectral structure, the tune-amplitude dependence, the variation of tune and amplitude during the particle motion, etc., using the method of Jordan decomposition which is widely used in conventional linear algebra.
Date: May 4, 2009
Creator: Yu,L. & Nash, B.
System: The UNT Digital Library
Microwave Instability Simulations for NSLS-II (open access)

Microwave Instability Simulations for NSLS-II

Potential-well distortion and the microwave instability in the NSLS-II storage ring are investigated. The longitudinal wakepotential is calculated as a sum of the contributions due to vacuum chamber components distributed around the ring. An approximation to the wakepotential for a 0.05-mm charge distribution length, much shorter than the 4.5-mm length of the unperturbed circulating bunch, is used as a pseudo-Green's function for beam dynamics simulations. Comparison of particle tracking simulations using the TRANFT code with the Haissinski solution shows good agreement below the instability threshold current. Above threshold two regimes are observed: (1) energy spread and bunch length are time-dependent (saw tooth behavior); (2) both are time-independent.
Date: May 4, 2009
Creator: Blednykh,A.; Krinsky, S.; Nash, B. & Yu, L.
System: The UNT Digital Library
Economics of residential gas furnaces and water heaters in United States new construction market (open access)

Economics of residential gas furnaces and water heaters in United States new construction market

New single-family home construction represents a significant and important market for the introduction of energy-efficient gas-fired space heating and water-heating equipment. In the new construction market, the choice of furnace and water-heater type is primarily driven by first cost considerations and the availability of power vent and condensing water heaters. Few analysis have been performed to assess the economic impacts of the different combinations of space and water-heating equipment. Thus, equipment is often installed without taking into consideration the potential economic and energy savings of installing space and water-heating equipment combinations. In this study, we use a life-cycle cost analysis that accounts for uncertainty and variability of the analysis inputs to assess the economic benefits of gas furnace and water-heater design combinations. This study accounts not only for the equipment cost but also for the cost of installing, maintaining, repairing, and operating the equipment over its lifetime. Overall, this study, which is focused on US single-family new construction households that install gas furnaces and storage water heaters, finds that installing a condensing or power-vent water heater together with condensing furnace is the most cost-effective option for the majority of these houses. Furthermore, the findings suggest that the new construction residential …
Date: May 6, 2009
Creator: Lekov, Alex B.; Franco, Victor H.; Wong-Parodi, Gabrielle; McMahon, James E. & Chan, Peter
System: The UNT Digital Library
NREL Gearbox Reliability Collaborative Analysis Round Robin: Preprint (open access)

NREL Gearbox Reliability Collaborative Analysis Round Robin: Preprint

The Gearbox Reliability Collaborative is working to determine the causes and loading conditions that result in the premature failure of wind turbine gearboxes.
Date: May 1, 2009
Creator: Oyague, F.; Butterfield, C. P. & Sheng, S.
System: The UNT Digital Library
The K- pi+ S-wave from the D+ --> k- pi+ pi+ Decay (open access)

The K- pi+ S-wave from the D+ --> k- pi+ pi+ Decay

Using data from FOCUS (E831) experiment at Fermilab, we present a model independent partial-wave analysis of the K{sup -}{pi}{sup +} S-wave amplitude from the decay D{sup +} {yields} K{sup -}{pi}{sup +}{pi}{sup +}. The S-wave is a generic complex function to be determined directly from the data fit. The P- and D-waves are parameterized by a sum of Breit-Wigner amplitudes. The measurement of the S-wave amplitude covers the whole elastic range of the K{sup -}{pi}{sup +} system.
Date: May 1, 2009
Creator: Link, J. M.; Yager, P. M.; /UC, Davis; Anjos, J. C.; Bediaga, I.; Castromonte, C. et al.
System: The UNT Digital Library
Human Factors and Data Fusion as Part of Control Systems Resilience (open access)

Human Factors and Data Fusion as Part of Control Systems Resilience

Human performance and human decision making is counted upon as a crucial aspect of overall system resilience. Advanced control systems have the potential to provide operators and asset owners a wide range of data, deployed at different levels that can be used to support operator situation awareness. However, the sheer amount of data available can make it challenging for operators to assimilate information and respond appropriately. This paper reviews some of the challenges and issues associated with providing operators with actionable state awareness and argues for the over arching importance of integrating human factors as part of intelligent control systems design and implementation. It is argued that system resilience is improved by implementing human factors in operations and maintenance. This paper also introduces issues associated with resilience and data fusion and highlights areas in which human factors including field studies hold promise.
Date: May 1, 2009
Creator: Gertman, David I.
System: The UNT Digital Library
Progress towards Managing Residential Electricity Demand: Impacts of Standards and Labeling for Refrigerators and Air Conditioners in India (open access)

Progress towards Managing Residential Electricity Demand: Impacts of Standards and Labeling for Refrigerators and Air Conditioners in India

The development of Energy Efficiency Standards and Labeling (EES&L) began in earnest in India in 2001 with the Energy Conservation Act and the establishment of the Indian Bureau of Energy Efficiency (BEE). The first main residential appliance to be targeted was refrigerators, soon to be followed by room air conditioners. Both of these appliances are of critical importance to India's residential electricity demand. About 15percent of Indian households own a refrigerator, and sales total about 4 million per year, but are growing. At the same time, the Indian refrigerator market has seen a strong trend towards larger and more consumptive frost-free units. Room air conditioners in India have traditionally been sold to commercial sector customers, but an increasing number are going to the residential sector. Room air conditioner sales growth in India peaked in the last few years at 20percent per year. In this paper, we perform an engineering-based analysis using data specific to Indian appliances. We evaluate costs and benefits to residential and commercial sector consumers from increased equipment costs and utility bill savings. The analysis finds that, while the BEE scheme presents net benefits to consumers, there remain opportunities for efficiency improvement that would optimize consumer benefits, according …
Date: May 30, 2009
Creator: McNeil, Michael A. & Iyer, Maithili
System: The UNT Digital Library
A Dual Triangle Timing Circuit for Improved Performance of 4-Quadrant H-Bridge Switches (open access)

A Dual Triangle Timing Circuit for Improved Performance of 4-Quadrant H-Bridge Switches

Fermilab is in the process of upgrading its Booster Correction Element System to include full field correction element magnets to correct position and chromaticity throughout the booster cycle. This upgrade requires power supplies with maximum outputs of {+-}180V/{+-}65A, with current bandwidths of 5k Hz and with slew rates of min to max current in 1ms. For seamless operation around zero current and voltage, we use continuous switching on both sides of the bridge. Although the straightforward way of coordinating the switching on both sides of the bridge can be accomplished with one triangle timing wave and one voltage reference, we have found that using two triangle waves yields a switching coordination that effectively doubles the frequency of the differential ripple on the load and allows for better filtering of the output ripple.
Date: May 1, 2009
Creator: Krafczyk, G.; Jensen, C.; Pfeffer, H.; Warchol, G. & /Fermilab
System: The UNT Digital Library
Sampling Artifacts from Conductive Silicone Tubing (open access)

Sampling Artifacts from Conductive Silicone Tubing

We report evidence that carbon impregnated conductive silicone tubing used in aerosol sampling systems can introduce two types of experimental artifacts: 1) silicon tubing dynamically absorbs carbon dioxide gas, requiring greater than 5 minutes to reach equilibrium and 2) silicone tubing emits organic contaminants containing siloxane that adsorb onto particles traveling through it and onto downstream quartz fiber filters. The consequence can be substantial for engine exhaust measurements as both artifacts directly impact calculations of particulate mass-based emission indices. The emission of contaminants from the silicone tubing can result in overestimation of organic particle mass concentrations based on real-time aerosol mass spectrometry and the off-line thermal analysis of quartz filters. The adsorption of siloxane contaminants can affect the surface properties of aerosol particles; we observed a marked reduction in the water-affinity of soot particles passed through conductive silicone tubing. These combined observations suggest that the silicone tubing artifacts may have wide consequence for the aerosol community and should, therefore, be used with caution. Gentle heating, physical and chemical properties of the particle carriers, exposure to solvents, and tubing age may influence siloxane uptake. The amount of contamination is expected to increase as the tubing surface area increases and as the …
Date: May 15, 2009
Creator: Timko, Michael T.; Yu, Zhenhong; Kroll, Jesse; Jayne, John T.; Worsnop, Douglas R.; Miake-Lye, Richard C. et al.
System: The UNT Digital Library