Through Weld Inspection of Wrought Stainless Steel Piping Using Phased-Array Ultrasonic Probes. (open access)

Through Weld Inspection of Wrought Stainless Steel Piping Using Phased-Array Ultrasonic Probes.

A study was conducted to assess the ability of phased-array ultrasonic techniques to detect and accurately determine the size of flaws from the far-side of wrought austenitic piping welds. Far-side inspections of these welds are currently performed on a “best effort” basis and do not conform to ASME Code Section XI Appendix VIII performance demonstration requirements. For this study, four circumferential welds in 610mm diameter, 36mm thick ASTM A-358, Grade 304 vintage austenitic stainless steel pipe were examined. The welds were fabricated with varied welding parameters; both horizontal and vertical pipe orientations were used, with air and water backing, to simulate field welding conditions. A series of saw cuts, electro-discharge machined (EDM) notches, and implanted fatigue cracks were placed into the heat affected zones of the welds. The saw cuts and notches range in depth from 7.5% to 28.4% through-wall. The implanted cracks ranged in depth from 5% through wall to 64% through wall. The welds were examined with two phased-array probes, a 2.0 MHz transmit-receive longitudinal wave array and a 2.0 MHz transmit-receive shear wave array. These examinations showed that both phased-array transducers were able to detect and accurately length-size, but not depth size, all of the notches and …
Date: August 5, 2004
Creator: Anderson, Michael T.; Cumblidge, Stephen E. & Doctor, Steven R.
System: The UNT Digital Library
Electric Current Enhanced Point Defect Mobility in Ni3Ti Intermetallic (open access)

Electric Current Enhanced Point Defect Mobility in Ni3Ti Intermetallic

The effect of the application of a DC current on the annealing of point defects in Ni{sub 3}Ti was investigated by positron annihilation spectroscopy (PAS). An increased rate of point defect annealing is observed under the influence of a current and is attributed to a 24% decrease in the mobility activation energy. The results are interpreted in terms of the electron wind effect and the complex nature of diffusion in ordered intermetallic phases. This work represents the first direct evidence of the role of the current on the mobility of point defects in intermetallic systems.
Date: February 5, 2004
Creator: Anselmi-Tamburini, U; Asoka-Kumar, P; Garay, J E; Munir, Z A & Glade, S C
System: The UNT Digital Library
Three-dimensional Global Model Approaches to Understanding Stratospheric Impacts on Tropospheric Ozone (open access)

Three-dimensional Global Model Approaches to Understanding Stratospheric Impacts on Tropospheric Ozone

None
Date: January 5, 2004
Creator: Atherton, C; Bergmann, D; Cameron-Smith, P; Connell, P; Dignon, J; Rotman, D et al.
System: The UNT Digital Library
STOCHASTIC COOLING STUDIES IN RHIC, II. (open access)

STOCHASTIC COOLING STUDIES IN RHIC, II.

Intra-beam scattering (IBS) is unavoidable for highly charged heavy ions and causes emittance growth during the store for collision physics. A longitudinal bunched beam stochastic cooling system will confine the bunch within the RF bucket increasing the useful luminosity. We describe a series of measurements in RHIC that have been used to verify our understanding of the relevant physics and the cooling system architecture that is being prototyped.
Date: July 5, 2004
Creator: BLASKIEWICZ,M. BRENNAN,J. M. WEI,J.
System: The UNT Digital Library
RF TECHNIQUES FOR IMPROVED LUMINOSITY IN RHIC. (open access)

RF TECHNIQUES FOR IMPROVED LUMINOSITY IN RHIC.

The luminosity of the Relativistic Heavy Ion Collider has improved significantly [1] over the first three physics runs. A number of special rf techniques have been developed to facilitate higher luminosity. The techniques described herein include: an ultra low-noise rf source for the 197 MHz storage rf system, a frequency shift switch-on technique for transferring bunches from the acceleration to the storage system, synchronizing the rings during the energy ramp (including crossing the transition energy) to avoid incidental collisions, installation of dedicated 200 MHZ cavities to provide longitudinal Landau damping on the ramp, and the development of a bunch merging scheme in the Booster to increase the available bunch intensity from the injectors.
Date: July 5, 2004
Creator: BRENNAN,J. M. BLASKIEWICZ,J. BUTLER,J. DELONG,J. FISCHER,W. HAYES,T.
System: The UNT Digital Library
RESULTS OF THE NASA SPACE RADIATION LABORATORY BEAM STUDIES PROGRAM AT BNL. (open access)

RESULTS OF THE NASA SPACE RADIATION LABORATORY BEAM STUDIES PROGRAM AT BNL.

The NASA Space Radiation Laboratory (NSRL) was constructed in collaboration with NASA for the purpose of performing radiation effect studies for the NASA space program. The NSRL makes use of heavy ions in the range of 0.05 to 3 GeV/n slow extracted from BNL's AGS Booster. The purpose of the NSRL Beam Studies Program is to develop a clear understanding of the beams delivered to the facility, to fully characterize those beams, and to develop new capabilities in the interest of understanding the radiation environment in space. In this report we will describe the first results from this program.
Date: July 5, 2004
Creator: BROWN,K. A. AHRENS,L. BEUTTENMULLER,R. H. ET AL.
System: The UNT Digital Library
RESULTS OF THE FIRST RUN OF THE NASA SPACE RADIATION LABORATORY AT BNL. (open access)

RESULTS OF THE FIRST RUN OF THE NASA SPACE RADIATION LABORATORY AT BNL.

The NASA Space Radiation Laboratory (NSRL) was constructed in collaboration with NASA for the purpose of performing radiation effect studies for the NASA space program. The results of commissioning of this new facility were reported in [l]. In this report we will describe the results of the first run. The NSRL is capable of making use of heavy ions in the range of 0.05 to 3 GeV/n slow extracted from BNL's AGS Booster. Many modes of operation were explored during the first run, demonstrating all the capabilities designed into the system. Heavy ion intensities from 100 particles per pulse up to 12 x 10{sup 9} particles per pulse were delivered to a large variety of experiments, providing a dose range up to 70 Gy/min over a 5 x 5 cm{sup 2} area. Results presented will include those related to the production of beams that are highly uniform in both the transverse and longitudinal planes of motion [2].
Date: July 5, 2004
Creator: BROWN,K. A. AHRENS,L. BRENNAN,J. M. ET. AL.
System: The UNT Digital Library
MINI-BUNCHED AND MICRO-BUNCHED SLOW EXTRACTED BEAMS FROM THE AGS. (open access)

MINI-BUNCHED AND MICRO-BUNCHED SLOW EXTRACTED BEAMS FROM THE AGS.

Brookhaven National Laboratory's (BNLs) Alternating Gradient Synchrotron (AGS) has a long history of providing slow extracted proton beams to fixed target experiments. This program of providing high quality high intensity beams continues with two new experiments currently being designed for operation at the AGS. Both experiments require slow extracted beam, but with an added requirement that those beams be bunched. Bunched beam slow extraction techniques have been developed for both experiments and initial tests have been performed. In this report we describe the beam requirements for the two experiments, and present results of detailed simulations and initial beam tests.
Date: July 5, 2004
Creator: BROWN,K. A. AHRENS,L. BRENNAN,J. M. GLENN,J. W. SIVERTZ,M. KOSCIELNIAK,S. R.
System: The UNT Digital Library
Non-Destructive Beam Measurements (open access)

Non-Destructive Beam Measurements

In high energy accelerators, especially storage rings, non-destructive beam measurements are highly desirable to minimize the impact on the beam quality. In principle, the non-destructive tools can be either passive detectors like Schottky, or active devices which excite either longitudinal or transverse beam motions for the corresponding measurements. An example of such a device is an ac dipole, a magnet with oscillating field, which can be used to achieve large coherent betatron oscillations. It has been demonstrated in the Brookhaven AGS that by adiabatically exciting the beam, the beam emittance growth due to the filamentation in the phase space can be avoided. This paper overviews both techniques in general. In particular, this paper also presents the beam tune measurement with a Schottky detector, phase advance measurements as well as nonlinear resonance measurements with the ac dipoles in the Brookhaven RHIC.
Date: July 5, 2004
Creator: Bai, M.
System: The UNT Digital Library
Poroelastic Fluid Effects on Shear for Rocks with Soft Anisotropy (open access)

Poroelastic Fluid Effects on Shear for Rocks with Soft Anisotropy

None
Date: January 5, 2004
Creator: Berger, E. L.
System: The UNT Digital Library
High Brightness Electron Guns for Next-Generation Light Sources and Accelerators. (open access)

High Brightness Electron Guns for Next-Generation Light Sources and Accelerators.

Next-generation light sources and accelerators are being proposed that set unique requirements for the electron source parameters. No single source is suitable for the diverse applications, which have operating characteristics ranging from high-average-current, quasi-CW, to high-peak-current, single-pulse electron beams. Advanced Energy Systems, in collaboration with our various partners, is developing a variety of electron gun concepts for these important applications.
Date: July 5, 2004
Creator: Bluem, H. P.; Ben-Zvi, Ilan; Srinivasan-Rao, T. & AL., ET
System: The UNT Digital Library
Spatially Continuous Mixed P2-P1 Solutions for Planar Geometry (open access)

Spatially Continuous Mixed P2-P1 Solutions for Planar Geometry

Even-order Legendre polynomial (PN) expansion approximations of the neutron transport equation have historically seen only limited practical application. Research in the last decade [1] has resolved one of the historical theoretical objections [2] to the use of even-order PN approximations in planar geometry, namely the ambiguity in the prescription of boundary conditions as a result of an odd number of unknowns. This research also demonstrated the P2 approximation to be more accurate than the P1 approximation in planar geometry away from boundary layers and material interfaces. Neither the P1 nor the P2 approximation is convincingly more accurate near material interfaces. This progress motivated the reexamination of the multidimensional simplified P2 (SP2) approximation [3], the development of P2 approximations for planar geometry stochastic transport problems [4], and the examination of the P2 and SP2 approximations as a synthetic acceleration technique for the discrete ordinates equations.
Date: August 5, 2004
Creator: Brantely, P S
System: The UNT Digital Library
Search for New Physics at a Super-B Factory (open access)

Search for New Physics at a Super-B Factory

The importance of a Super-B Factory in the search for New Physics, in particular, due to CP-od phase(s) from physics beyond the Standard Model is surveyed. The first point to emphasize is that we know now how to directly measure all three angles of the unitarity triangle very cleanly, i. e. without theoretical assumptions with irreducible theory error {le} 1%; however this requires much more luminosity than is currently available at B-factories. Direct searches via penguin-dominated hadronic modes as well as radiative, pair-leptonic and semi-leptonic decays are also discussed. Null tests of the SM are stressed as these will play a crucial role especially if the effects of BSM phase(s) on B-physics are small.
Date: January 5, 2004
Creator: Browder, T. E. & Soni, A.
System: The UNT Digital Library
[Washington Blade marriage amendment coverage, March 5, 2004] (open access)

[Washington Blade marriage amendment coverage, March 5, 2004]

A front page from the Washington Blade newspaper covering responses to the recent candidate and Presidential support of a same-sex marriage ban. The first covers John Kerry, a Democratic nominee, announcing his support of a same-sex marriage ban in the Massachusetts Constitution and the response. The second covers the resignation of an appointee to the George W. Bush Presidential administration following Bush's support of the marriage-ban being added to the Constitution.
Date: March 5, 2004
Creator: Brune, Adrian & Chibbaro, Lou, Jr.
System: The UNT Digital Library
HIGH CURRENT SUPERCONDUCTING CAVITIES AT RHIC. (open access)

HIGH CURRENT SUPERCONDUCTING CAVITIES AT RHIC.

A five-cell high current superconducting cavity for the electron cooling project at RHIC is under fabrication. Higher order modes (HOMs), one of main limiting factors for high current energy-recovery operation, are under investigation. Calculations of HOMs using time-domain methods in Mafia will be discussed and compared to calculations in the frequency domain. Beam breakup thresholds determined from numerical codes for the five-cell cavity will be presented. A possible motivation towards a 2 x 2 superstructure using the current five-cell design will also be discussed.
Date: July 5, 2004
Creator: CALAGA,R. BEN-ZVI,I. ZHAO,Y. ET AL.
System: The UNT Digital Library
RHIC BPM Performance: Comparison of Run 2003 and 2004. (open access)

RHIC BPM Performance: Comparison of Run 2003 and 2004.

Identification of malfunctioning beam position monitors (BPMs) play an important role in any orbit or turn-by-turn analysis. Singular value decomposition (SVD) and Fourier transform methods were recently employed to identify malfunctioning BPMs at RHIC. A detailed statistical comparison between the two methods for Run 2003 was in good agreement and proved to be a robust method to identify faulty BPMs. We evaluate detailed BPM performance for different upgrades of BPM low-level software during Run 2003 and 2004.
Date: July 5, 2004
Creator: Calaga, R.
System: The UNT Digital Library
Transverse Coupling Measurement Using SVD Modes From Beam Histories. (open access)

Transverse Coupling Measurement Using SVD Modes From Beam Histories.

In this report we investigate the measurement of local transverse coupling from turn-by-turn data measured at a large number of beam position monitors. We focus on a direct measurement of coupled lattice functions using the singular value decomposition (SVD) modes and explore the accuracy of this method.
Date: July 5, 2004
Creator: Calaga, R. & Wang, C.
System: The UNT Digital Library
RHIC OPTICS MEASUREMENTS AT DIFFERENT WORKING POINTS. (open access)

RHIC OPTICS MEASUREMENTS AT DIFFERENT WORKING POINTS.

Working point scans at RHIC were performed during 2004 to determine the effect on lifetime and luminosity. Linear optics were measured for different working point tunes by exciting coherent oscillations with the aid of RHIC AC dipoles. Two methods are currently used to measure the beta functions and phases advances: a conventional fitting technique, and an alternate method based on singular value decomposition (SVD). This paper focuses on the effect of working point on the measurement of linear optics using a SVD based technique. The use of a 3-bump beta wave algorithm to identify quadrupole error sources is also presented.
Date: July 5, 2004
Creator: Calaga, R.; Bai, M.; Peggs, S.; Roser, T. & Satogata, T.
System: The UNT Digital Library
Measuring Local Gradient and Skew Quadrupole Errors in Rhic Irs. (open access)

Measuring Local Gradient and Skew Quadrupole Errors in Rhic Irs.

The measurement of local linear errors at RHIC interaction regions using an ''action and phase'' analysis of difference orbits has already been presented. This paper evaluates the accuracy of this technique using difference orbits that were taken when known gradient errors and skew quadrupole errors were intentionally introduced. It also presents action and phase analysis of simulated orbits when controlled errors are intentionally placed in a RHIC simulation model.
Date: July 5, 2004
Creator: Cardona, J.; Peggs, S.; Pilat, R. & Ptitsyn, V.
System: The UNT Digital Library
Adapting high-resolution speckle imaging to moving targets and platforms (open access)

Adapting high-resolution speckle imaging to moving targets and platforms

High-resolution surveillance imaging with apertures greater than a few inches over horizontal or slant paths at optical or infrared wavelengths will typically be limited by atmospheric aberrations. With static targets and static platforms, we have previously demonstrated near-diffraction limited imaging of various targets including personnel and vehicles over horizontal and slant paths ranging from less than a kilometer to many tens of kilometers using adaptations to bispectral speckle imaging techniques. Nominally, these image processing methods require the target to be static with respect to its background during the data acquisition since multiple frames are required. To obtain a sufficient number of frames and also to allow the atmosphere to decorrelate between frames, data acquisition times on the order of one second are needed. Modifications to the original imaging algorithm will be needed to deal with situations where there is relative target to background motion. In this paper, we present an extension of these imaging techniques to accommodate mobile platforms and moving targets.
Date: February 5, 2004
Creator: Carrano, C J & Brase, J M
System: The UNT Digital Library
Acceleressence: Dark energy from a phase transition at the seesawscale (open access)

Acceleressence: Dark energy from a phase transition at the seesawscale

Simple models are constructed for ''acceleressence'' dark energy: the latent heat of a phase transition occurring in a hidden sector governed by the seesaw mass scale v{sup 2}/M{sub Pl}, where v is the electroweak scale and M{sub Pl} the gravitational mass scale. In our models, the seesaw scale is stabilized by supersymmetry, implying that the LHC must discover superpartners with a spectrum that reflects a low scale of fundamental supersymmetry breaking. Newtonian gravity may be modified by effects arising from the exchange of fields in the acceleressence sector whose Compton wavelengths are typically of order the millimeter scale. There are two classes of models. In the first class the universe is presently in a metastable vacuum and will continue to inflate until tunneling processes eventually induce a first order transition. In the simplest such model, the range of the new force is bounded to be larger than 25 {micro}m in the absence of fine-tuning of parameters, and for couplings of order unity it is expected to be {approx} 100 {micro}m. In the second class of models thermal effects maintain the present vacuum energy of the universe, but on further cooling, the universe will ''soon'' smoothly relax to a matter dominated …
Date: October 5, 2004
Creator: Chacko, Z.; Hall, Lawrence J. & Nomura, Yasunori
System: The UNT Digital Library
Beam Conditioning and Harmonic Generation in Free ElectronLasers (open access)

Beam Conditioning and Harmonic Generation in Free ElectronLasers

The next generation of large-scale free-electron lasers (FELs) such as Euro-XFEL and LCLS are to be devices which produce coherent X-rays using Self-Amplified Spontaneous Emission (SASE). The performance of these devices is limited by the spread in longitudinal velocities of the beam. In the case where this spread arises primarily from large transverse oscillation amplitudes, beam conditioning can significantly enhance FEL performance. Future X-ray sources may also exploit harmonic generation starting from laser-seeded modulation. Preliminary analysis of such devices is discussed, based on a novel trial-function/variational-principle approach, which shows good agreement with more lengthy numerical simulations.
Date: July 5, 2004
Creator: Charman, A.E.; Penn, G.; Wolski, A. & Wurtele, J.S.
System: The UNT Digital Library
An Upgrade for the Advanced Light Source (open access)

An Upgrade for the Advanced Light Source

One of the first third-generation synchrotron light sources, the ALS, has been operating for almost a decade at Berkeley Lab, where experimenters have been exploiting its high brightness for forefront science. However, accelerator and insertion-device technology have significantly changed since the ALS was designed. As a result, the performance of the ALS is in danger of being eclipsed by that of newer, more advanced sources. The ALS upgrade that we are planning includes full-energy, top-off injection with higher storage-ring current and the replacement of five first-generation insertion devices with nine state-of-the art insertion devices and four new application-specific beamlines now being identified in a strategic planning process. The upgrade will help keep the ALS at the forefront of soft x-ray synchrotron light sources for the next two decades.
Date: August 5, 2004
Creator: Chemla, Daniel S.; Feinberg, Benedict; Hussain, Zahid; Kirz,Janos; Krebs, Gary F.; Padmore, Howard A. et al.
System: The UNT Digital Library
Ductile, Brittle Failure Characteristics as Determined by the State of the Material and the Imposed State of Stress (open access)

Ductile, Brittle Failure Characteristics as Determined by the State of the Material and the Imposed State of Stress

A method is developed for determining whether a particular mode of failure is expected to be of ductile type or brittle type depending upon both the state of the material and the particular state of stressing the isotropic material to failure. The state of the material is determined by two specific failure properties and a newly formulated failure theory. The ductile versus brittle criterion then involves the state of the material specification and the mean normal stress part of the imposed stress state. Several examples are given for different stress states and a spectrum of materials types. Closely related to the failure mode types are the orientations of the associated failure surfaces. The resulting failure surface angle predictions are compared with those from the Coulomb-Mohr failure criterion. In uniaxial tension, only the present method correctly predicts the octahedral failure angle at the ductile limit, and also shows a distinct failure mode transition from ductile type to brittle type as the state of the material changes. The explicit D-B criterion and the related failure surface orientation methodology are intended to provide a refinement and generalization of the ductile-brittle transition viewed only as a state property to also include a dependence upon …
Date: February 5, 2004
Creator: Christensen, R M
System: The UNT Digital Library