Setup and Performance of the Rhic Injector Accelerators for the 2007 Run With Gold Ions (open access)

Setup and Performance of the Rhic Injector Accelerators for the 2007 Run With Gold Ions

Gold ions for the 2007 run of the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL) are accelerated in the Tandem, Booster and AGS prior to injection into RHIC. The setup and performance of this chain of accelerators is reviewed with a focus on improvements in the quality of beam delivered to RHIC. In particular, more uniform stripping foils between Booster and AGS7 and a new bunch merging scheme in AGS have provided beam bunches with reduced longitudinal emittance for RHIC.
Date: June 25, 2007
Creator: Gardner, C.; Ahrens, L.; Alessi, J.; Benjamin, J.; Blaskiewicz, M. & Al., Et
System: The UNT Digital Library
Uniform Beam Distributions at the Target of the NSRL Beam Transfer Line (open access)

Uniform Beam Distributions at the Target of the NSRL Beam Transfer Line

Uniform irradiation of biological or material samples with charged particle beams is desired by experimenters because it reduces radiation dose errors. In this paper we present results of uniform beams produced in the NASA SPACE RADIATION LABORATORY (NSRL) at the Brookhaven National Laboratory (BNL) by a method which was developed theoretically and was proven experimentally at BNL. A similar method which requires collimation of the beam, and also lacks the flexibility of the present method to produce beam various beam sizes at the target, was patented in the year 1988. The present method of producing uniform beam distributions on a plane transverse to the direction of the beam, is based on purely magnetic focusing of the beam and requires no collimation of the beam or any other type of beam interaction with materials. It can also generate uniform beam distributions of various sizes. The method is favorably compared with alternative methods of producing uniform beam distributions and can be applied to the whole energy spectrum of the charged particle beams that are delivered by the BNL Booster synchrotron.
Date: June 25, 2007
Creator: Tsoupas, N.; Ahrens, L.; Brown, K. Chiang, I-Hung, Gardner, C. J.; MacKay, W. W.; Pile, P. & Rusek, A.
System: The UNT Digital Library
Overcoming Depolarizing Resonances in the AGS With Two Helical Partial Snakes (open access)

Overcoming Depolarizing Resonances in the AGS With Two Helical Partial Snakes

Dual partial snake scheme has provided polarized proton beams with 1.5 x 10{sup 11} intensity and 65% polarization for the Relativistic Heavy Ion Collider (RHIC) spin program. To overcome the residual polarization loss due to horizontal resonances in the Brookhaven Alternating Gradient Synchrotron (AGS), a new string of quadrupoles have been added. The horizontal tune can then be set in the spin tune gap generated by the two partial snakes, such that horizontal resonances can also be avoided. This paper presents the accelerator setup and preliminary results.
Date: June 25, 2007
Creator: Huang, H.; Ahrens, L.; Bai, M.; Brown, K. A.; Gardner, C. J.; Glenn, J. W. et al.
System: The UNT Digital Library
Quantifying the surface-subsurface biogeochemical coupling during the VERTIGO ALOHA and K2 studies (open access)

Quantifying the surface-subsurface biogeochemical coupling during the VERTIGO ALOHA and K2 studies

A central question addressed by the VERTIGO (VERtical Transport In the Global Ocean) study was 'What controls the efficiency of particle export between the surface and subsurface ocean'? Here, we present data from sites at ALOHA (N Central Pacific Gyre) and K2 (NW subarctic Pacific) on phytoplankton processes, and relate them via a simple planktonic foodweb model, to subsurface particle export (150-500 m). Three key factors enable quantification of the surface-subsurface coupling: a sampling design to overcome the temporal lag and spatial displacement between surface and subsurface processes; data on the size-partitioning of Net Primary Production (NPP) and subsequent transformations prior to export; estimates of the ratio of algal- to faecal-mediated vertical export flux. At ALOHA, phytoplankton were characterized by low stocks, NPP, F{sub v}/F{sub m} (N-limited), and were dominated by picoplankton. The HNLC waters at K2 were characterized by both two-fold changes in NPP and floristic shifts (high to low proportion of diatoms) between deployment 1 and 2. Prediction of export exiting the euphotic zone was based on size-partitioning of NPP, a copepod-dominated foodweb and a ratio of 0.2 (ALOHA) and 0.1 (K2) for algal:faecal particle flux. Predicted export was 20-22 mg POC m{sup -2} d{sup -1} at ALOHA …
Date: February 25, 2008
Creator: Boyd, P. W.; Gall, M. P.; Silver, M. W.; Bishop, J. K. B.; Coale, Susan L. & Bidigare, Robert R.
System: The UNT Digital Library
Mitotic Exit Control as an Evolved Complex System (open access)

Mitotic Exit Control as an Evolved Complex System

The exit from mitosis is the last critical decision a cell has to make during a division cycle. A complex regulatory system has evolved to evaluate the success of mitotic events and control this decision. Whereas outstanding genetic work in yeast has led to rapid discovery of a large number of interacting genes involved in the control of mitotic exit, it has also become increasingly difficult to comprehend the logic and mechanistic features embedded in the complex molecular network. Our view is that this difficulty stems in part from the attempt to explain mitotic exit control using concepts from traditional top-down engineering design, and that exciting new results from evolutionary engineering design applied to networks and electronic circuits may lend better insights. We focus on four particularly intriguing features of the mitotic exit control system: the two-stepped release of Cdc14; the self-activating nature of Tem1 GTPase; the spatial sensor associated with the spindle pole body; and the extensive redundancy in the mitotic exit network. We attempt to examine these design features from the perspective of evolutionary design and complex system engineering.
Date: April 25, 2005
Creator: Bosl, W & Li, R
System: The UNT Digital Library
Particulate matter chemistry and dynamics in the Twilight Zone at VERTIGO ALOHA and K2 Sites (open access)

Particulate matter chemistry and dynamics in the Twilight Zone at VERTIGO ALOHA and K2 Sites

Understanding particle dynamics in the 'Twilight Zone' is critical to prediction of the ocean's carbon cycle. As part of the VERTIGO (VERtical Transformations In the Global Ocean) project, this rarely sampled regime extending from the base of the euphotic layer to 1000 m, was characterized by double-paired day/night Multiple Unit Large Volume in-situ Filtration System (MULVFS) deployments and by {approx}100 high-frequency CTD/transmissometer/turbidity sensor profiles. VERTIGO studies lasting three weeks, contrasted oligotrophic station ALOHA (22.75{sup o}N 158{sup o}W), sampled in June-July 2004, with a biologically productive location (47{sup o}N 161{sup o}E) near station K2 in the Oyashio, occupied July-August 2005. Profiles of major and minor particulate components (C{sub org}, N, P, Ca, Si, Sr, Ba, Mn) in <1, 1-51, and >51 {micro}m size fractions, in-water optics, neutrally buoyant sediment trap (NBST) fluxes, and zooplankton data were intercompared. MULVFS total C{sub org} and C-Star particle beam attenuation coefficient (C{sub P}) were consistently related at both sites with a 27 {micro}M m{sup -1} conversion factor. 26 At K2, C{sub P} profiles further showed a multitude of transient spikes throughout the water column and spike abundance profiles closely paralleled the double peaked abundance profiles of zooplankton. Also at K2, copepods contributed {approx}40% and 10%, …
Date: March 25, 2008
Creator: Bishop, James K.B. & Wood, T.J.
System: The UNT Digital Library
Accelerating Polarized Protons to 250 GEV (open access)

Accelerating Polarized Protons to 250 GEV

The Relativistic Heavy Ion Collider (RHIC) as the first high energy polarized proton collider was designed t o provide polarized proton collisions a t a maximum beam energy of 250 GeV. I t has been providing collisions a t a beam energy of 100 Gel' since 2001. Equipped with two full Siberian snakes in each ring, polarization is preserved during the acceleration from injection to 100 GeV with careful control of the betatron tunes and the vertical orbit distortions. However, the intrinsic spin resonances beyond 100 GeV are about a factor of two stronger than those below 100 GeV? making it important t o examine the impact of these strong intrinsic spin resonances on polarization survival and the tolerance for vertical orbit distortions. Polarized protons were accelerated t o the record energy of 250 GeV in RHIC with a polarization of 46% measured a t top energy in 2006. The polarization measurement as a function of beam energy also shows some polarization loss around 136 GeV, the first strong intrinsic resonance above 100 GeV. This paper presents the results and discusses the sensitivity of the polarization survival t o orbit distortions.
Date: June 25, 2007
Creator: Bai, M.; Ahrens, L.; Alekseev, I. G.; Alessi, J.; Beebe-Wang, J. & AL., ET
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
Sensitivity analysis for joint inversion of ground-penetratingradar and thermal-hydrological data from a large-scale underground heatertest (open access)

Sensitivity analysis for joint inversion of ground-penetratingradar and thermal-hydrological data from a large-scale underground heatertest

We describe a joint inversion approach that combinesgeophysical and thermal-hydrological data for the estimation of (1)thermal-hydrological parameters (such as permeability, porosity, thermalconductivity, and parameters of the capillary pressure and relativepermeability functions) that are necessary for predicting the flow offluids and heat in fractured porous media, and (2) parameters of thepetrophysical function that relates water saturation, porosity andtemperature to the dielectric constant. The approach incorporates thecoupled simulation of nonisothermal multiphase fluid flow andground-penetrating radar (GPR) travel times within an optimizationframework. We discuss application of the approach to a large-scale insitu heater test which was conducted at Yucca Mountain, Nevada, to betterunderstand the coupled thermal, hydrological, mechanical, and chemicalprocesses that may occur in the fractured rock mass around a geologicrepository for high-level radioactive waste. We provide a description ofthe time-lapse geophysical data (i.e., cross-borehole ground-penetratingradar) and thermal-hydrological data (i.e., temperature and water contentdata) collected before and during the four-year heating phase of thetest, and analyze the sensitivity of the most relevantthermal-hydrological and petrophysical parameters to the available data.To demonstrate feasibility of the approach, and as a first step towardcomprehensive inversion of the heater test data, we apply the approach toestimate one parameter, the permeability of the rock matrix.
Date: June 25, 2007
Creator: Kowalsky, M. B.; Birkholzer, J.; Peterson, J.; Finsterle, S.; Mukhopadhya, Y. S. & Tsang, Y. T.
System: The UNT Digital Library
Novel QCD Phenomena at Electron-Proton Colliders (open access)

Novel QCD Phenomena at Electron-Proton Colliders

I discuss several novel phenomenological features of QCD which are observable in deep inelastic lepton-nucleon and lepton-nucleus scattering. Initial- and final-state interactions from gluon exchange, normally neglected in the parton model, have a profound effect on QCD hard-scattering reactions, leading to leading-twist single-spin asymmetries, the diffractive contribution to deep inelastic scattering, and the breakdown of the pQCD Lam-Tung relation in Drell-Yan reactions. Leading-twist diffractive processes in turn lead to nuclear shadowing and non-universal antishadowing--physics not incorporated in the light-front wavefunctions of the nucleus computed in isolation.
Date: July 25, 2008
Creator: Brodsky, Stanley J. & /SLAC /Durham U., IPPP
System: The UNT Digital Library
Edge Zonal Flows and Blob Propagation in Alcator C-Mod (open access)

Edge Zonal Flows and Blob Propagation in Alcator C-Mod

Here we describe recent measurements of the 2-D motion of turbulence in the edge and scrape-off layer (SOL) of the Alcator C-Mod tokamak. This data was taken using the outer midplane gas puff imaging (GPI) camera, which views a 6 cm radial by 6 cm poloidal region near the separatrix just below the outer midplane [1]. The data were taken in Ohmic or RF heated L-mode plasmas at 400,000 frames/sec for {approx}50 msec/shot using a Phantom 710 camera in a 64 x 64 pixel format. The resulting 2-D vs. time movies [2] can resolve the structure and motion of the turbulence on a spatial scale covering 0.3-6 cm. The images were analyzed using either a 2-D cross-correlation code (Sec. 2) or a 2-D blob tracking code (Sec. 3).
Date: July 25, 2011
Creator: Zweben, S; Agostini, M; Davis, B; Grulke, O; Hager, R; Hughes, J et al.
System: The UNT Digital Library
Dissecting the Gravitational Lens B1608 656. I. Lens Potential Reconstruction (open access)

Dissecting the Gravitational Lens B1608 656. I. Lens Potential Reconstruction

None
Date: April 25, 2013
Creator: Suyu, S. H.; Marshall, P. J.; Blandford, R. D.; Fassnacht, C. D.; Koopmans, L. V. E.; McKean, J. P. et al.
System: The UNT Digital Library
Microseismic Monitoring of the Mounds Drill Cuttings Injection Tests (open access)

Microseismic Monitoring of the Mounds Drill Cuttings Injection Tests

This paper describes the microseismic mapping of repeated injections of drill cuttings into two separate formations at a test site near Mounds, OK. Injections were performed in sandstone and shale formations at depths of 830 and 595 m, respectively. Typical injection disposal was simulated using multiple small-volume injections over a three-day period, with long shut-in periods interspersed between the injections. Microseismic monitoring was achieved using a 5-level array of wireline-run, triaxial- accelerometer receivers in a monitor well 76 m from the disposed well. Results of the mapped microseismic locations showed that the disposal domti W= generally aligns with the major horizontal stress with some variations in azimuth and that wide variations in height and length growth occurred with continued injections. These experiments show that the cuttings injection process cm be adequately monitored from a downhole, wireline-run receiver array, thus providing process control and environmental assurance.
Date: January 25, 1999
Creator: Branagan, P. T.; Mahrer, K. D.; Moschovidis, Z. A.; Warpinski, N. R. & Wolhart, S. L.
System: The UNT Digital Library
Computation at the edge of chaos: Phase transition and emergent computation (open access)

Computation at the edge of chaos: Phase transition and emergent computation

In order for computation to emerge spontaneously and become an important factor in the dynamics of a system, the material substrate must support the primitive functions required for computation: the transmission, storage, and modification of information. Under what conditions might we expect physical systems to support such computational primitives This paper presents research on Cellular Automata which suggests that the optimal conditions for the support of information transmission, storage, and modification, are achieved in the vicinity of a phase transition. We observe surprising similarities between the behaviors of computations and systems near phase-transitions, finding analogs of computational complexity classes and the Halting problem within the phenomenology of phase-transitions. We conclude that there is a fundamental connection between computation and phase-transitions, and discuss some of the implications for our understanding of nature if such a connection is borne out. 31 refs., 16 figs.
Date: January 25, 1990
Creator: Langton, C.
System: The UNT Digital Library
Upper Limit on the Cosmological Gamma-ray Background (open access)

Upper Limit on the Cosmological Gamma-ray Background

None
Date: November 25, 2013
Creator: Inoue, Yoshiyuki & Ioka, Kunihito
System: The UNT Digital Library
Unbound Particles in Dark Matter Halos (open access)

Unbound Particles in Dark Matter Halos

None
Date: April 25, 2013
Creator: Behroozi, Peter S.; /KIPAC, Menlo Park /Stanford U., Phys. Dept. /SLAC; Loeb, Abraham; U., /Harvard; Wechsler, Risa H. & /KIPAC, Menlo Park /Stanford U., Phys. Dept. /SLAC
System: The UNT Digital Library
Genomes, Phylogeny, and Evolutionary Systems Biology (open access)

Genomes, Phylogeny, and Evolutionary Systems Biology

With the completion of the human genome and the growing number of diverse genomes being sequenced, a new age of evolutionary research is currently taking shape. The myriad of technological breakthroughs in biology that are leading to the unification of broad scientific fields such as molecular biology, biochemistry, physics, mathematics and computer science are now known as systems biology. Here I present an overview, with an emphasis on eukaryotes, of how the postgenomics era is adopting comparative approaches that go beyond comparisons among model organisms to shape the nascent field of evolutionary systems biology.
Date: March 25, 2005
Creator: Medina, Monica
System: The UNT Digital Library
Theoretical status of {epsilon}{prime}/{epsilon} (open access)

Theoretical status of {epsilon}{prime}/{epsilon}

The author gives a detailed introduction into the theoretical formalism for {epsilon}{prime}/{epsilon}, which measures direct CP-violation in K {yields} {pi}{pi} decays. The current status of hadronic matrix elements and the strange quark mass is discussed. Several possible explanations of the unexpectedly high experimental results for {epsilon}{prime}/{epsilon} are pointed out: A small strange quark mass, an enhancement of the hadronic parameter B{sub 6}{sup (1/2)} from the {sigma} resonance, an underestimate of isospin breaking and possible new physics contributions in the {bar s}dZ-vertex and the {bar s}d-gluon-vertex.
Date: October 25, 1999
Creator: Nierste, Ulrich
System: The UNT Digital Library
Characterization and Research on Mechanical Properties of Bamboo Plastic Composites (open access)

Characterization and Research on Mechanical Properties of Bamboo Plastic Composites

This article observes the mechanical properties of bamboo plastic composites (BPCs) with bamboo pulp fiber (BPF) or white mud (WM).
Date: July 1, 2018
Creator: Xian, Yu; Ma, Dongjuan; Wang, Cuicui; Wang, Ge; Smith, Lee M. & Cheng, Haitao
System: The UNT Digital Library
Characterization and Research on Mechanical Properties of Bamboo Plastic Composites (open access)

Characterization and Research on Mechanical Properties of Bamboo Plastic Composites

This article describes a study to observe the mechanical properties of bamboo plastic composites with bamboo pulp fiber or white mud.
Date: July 25, 2018
Creator: Xian, Yu; Ma, Dongjuan; Wang, Cuicui; Wang, Ge; Smith, Lee M. & Cheng, Haitao
System: The UNT Digital Library
Flammability Control In A Nuclear Waste Vitrification System (open access)

Flammability Control In A Nuclear Waste Vitrification System

The Defense Waste Processing Facility at the Savannah River Site processes high-level radioactive waste from the processing of nuclear materials that contains dissolved and precipitated metals and radionuclides. Vitrification of this waste into borosilicate glass for ultimate disposal at a geologic repository involves chemically modifying the waste to make it compatible with the glass melter system. Pretreatment steps include removal of excess aluminum by dissolution and washing, and processing with formic and nitric acids to: 1) adjust the reduction-oxidation (redox) potential in the glass melter to reduce radionuclide volatility and improve melt rate; 2) adjust feed rheology; and 3) reduce by steam stripping the amount of mercury that must be processed in the melter. Elimination of formic acid in pretreatment has been studied to eliminate the production of hydrogen in the pretreatment systems, which requires nuclear grade monitoring equipment. An alternative reductant, glycolic acid, has been studied as a substitute for formic acid. However, in the melter, the potential for greater formation of flammable gases exists with glycolic acid. Melter flammability is difficult to control because flammable mixtures can be formed during surges in offgases that both increase the amount of flammable species and decrease the temperature in the vapor …
Date: July 25, 2013
Creator: Zamecnik, John R.; Choi, Alexander S.; Johnson, Fabienne C.; Miller, Donald H.; Lambert, Daniel P.; Stone, Michael E. et al.
System: The UNT Digital Library