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BENCHMARKING UPGRADED HOTSPOT DOSE CALCULATIONS AGAINST MACCS2 RESULTS (open access)

BENCHMARKING UPGRADED HOTSPOT DOSE CALCULATIONS AGAINST MACCS2 RESULTS

The radiological consequence of interest for a documented safety analysis (DSA) is the centerline Total Effective Dose Equivalent (TEDE) incurred by the Maximally Exposed Offsite Individual (MOI) evaluated at the 95th percentile consequence level. An upgraded version of HotSpot (Version 2.07) has been developed with the capabilities to read site meteorological data and perform the necessary statistical calculations to determine the 95th percentile consequence result. These capabilities should allow HotSpot to join MACCS2 (Version 1.13.1) and GENII (Version 1.485) as radiological consequence toolbox codes in the Department of Energy (DOE) Safety Software Central Registry. Using the same meteorological data file, scenarios involving a one curie release of {sup 239}Pu were modeled in both HotSpot and MACCS2. Several sets of release conditions were modeled, and the results compared. In each case, input parameter specifications for each code were chosen to match one another as much as the codes would allow. The results from the two codes are in excellent agreement. Slight differences observed in results are explained by algorithm differences.
Date: April 30, 2009
Creator: Brotherton, Kevin
System: The UNT Digital Library
Commissioning Results of the Upgraded Neutralized Drift Compression Experiment (open access)

Commissioning Results of the Upgraded Neutralized Drift Compression Experiment

Recent changes to the NDCX beamline offer the promise of higher charge compressed bunches (>15nC), with correspondingly large intensities (>500kW/cm2), delivered to the target plane for ion-beam driven warm dense matter experiments. We report on commissioning results of the upgraded NDCX beamline that includes a new induction bunching module with approximately twice the volt-seconds and greater tuning flexibility, combined with a longer neutralized drift compression channel.
Date: April 30, 2009
Creator: Lidia, S. M.; Roy, P. K.; Seidl, P. A.; Waldron, W. L. & Gilson, E. P.
System: The UNT Digital Library
A [Cyclentetrakis(methylene)]tetrakis[2-hydroxybenzamide]Ligand That Complexes and Sensitizes Lanthanide(III) Ions (open access)

A [Cyclentetrakis(methylene)]tetrakis[2-hydroxybenzamide]Ligand That Complexes and Sensitizes Lanthanide(III) Ions

The synthesis of a cyclen derivative containing four isophthalamide groups (L{sup 1}) is described. The spectroscopic properties of the Ln(III) complexes of L{sup 1} (Ln = Gd, Tb, Yb, Eu) reveal changes of the UV/visible absorption, circular dichroism absorption, luminescence and circularly polarized luminescence properties. It is shown that at least two metal complex species are present in solution, whose relative amounts are pH dependent. When at pH > 8.0, an intense long lived emission is observed (for [L{sup 1}Tb] and [L{sup 1}Yb]) while at pH < 8.0, a weaker, shorter-lived species predominates. Unconventional Ln(III) emitters (Pr, Nd, Sm, Dy and Tm) were sensitized in basic solution, both in the visible and in the near infra-red, to measure the emission of these ions.
Date: April 30, 2009
Creator: D'Aleo, Anthony; Xu, Jide; Do, King; Muller, Gilles & Raymond, Kenneth N.
System: The UNT Digital Library
Fast Correction Optics to Reduce Chromatic Aberrations in Longitudinally Compressed Ion Beams (open access)

Fast Correction Optics to Reduce Chromatic Aberrations in Longitudinally Compressed Ion Beams

Longitudinally compressed ion beam pulses are currently employed in ion-beam based warm dense matter studies [1]. Compression arises from an imposed time-dependent longitudinal velocity ramp followed by drift in a neutralized channel. Chromatic aberrations in the final focusing system arising from this chirp increase the attainable beam spot and reduce the effective fluence on target. We report recent work on fast correction optics that remove the time-dependent beam envelope divergence and minimizes the beam spot on target. We present models of the optical element design and predicted ion beam fluence.
Date: April 30, 2009
Creator: Lidia, S.M.; Lee, E.P.; Ogata, D.; Seidl, P.A.; Waldron, W.L. & Lund, S.M.
System: The UNT Digital Library
FLUOR'S USE OF LEADING INDICATORS - LESSONS, THEORY & PRACTICE (open access)

FLUOR'S USE OF LEADING INDICATORS - LESSONS, THEORY & PRACTICE

None
Date: April 30, 2009
Creator: SS, PREVETTE
System: The UNT Digital Library
Laser Timing Jitter Measurements using a Dual-Sweep Streak Camera at the A0 Photoinjector (open access)

Laser Timing Jitter Measurements using a Dual-Sweep Streak Camera at the A0 Photoinjector

Excellent phase stability of the drive laser is a critical performance specification of photoinjectors such as Fermilab's A0 photoinjector (A0PI). Previous efforts based on the measurement of the power spectrum of the signal of a fast photodiode illuminated by the mode locked infrared laser pulse component indicated a phase jitter of less than 1.4 ps (technique limited). A recently procured dual sweep plugin unit and existing Hamamatsu C5680 streak camera were used to study the phase stability of the UV laser pulse component. Initial measurements with the synchroscan vertical sweep unit locked to 81.25 MHz showed that the phase slew through the micropulse train and the phase jitter micropulse to micropulse were two key aspects that could be evaluated. The phase slew was much less than 100 fs per micropulse, and the total phase jitter (camera, trigger, and laser) was approximately 300 fs RMS for measurements of 50-micropulse trains. Data on the macropulse phase stability were also obtained. A possible upgrade to achieve better phase stability will be also discussed.
Date: April 30, 2009
Creator: Ruan, J.; Lumpkin, A. H. & Santucci, J. K.
System: The UNT Digital Library
Linear pi-Acceptor-Templated Dynamic Clipping to Macrobicycles and[2]Rotaxanes (open access)

Linear pi-Acceptor-Templated Dynamic Clipping to Macrobicycles and[2]Rotaxanes

Functional rotaxanes are one of the representative nanoscale molecular machines that have found applications in many areas, including molecular electronics, nanoelectromechanical systems (NEMS), photo controllable smart surfaces, and nanovalves. With the advent of molecular recognition and self-assembly, such molecular compounds can now be obtained efficiently through template-directed synthesis. One of the common strategies of making [2]rotaxanes involves the clipping of a macrocycle around a preformed dumbbell-shaped template in a [1+1] or [2+2] manner. While early examples were based on irreversible kinetic pathway through covalent bond formation, recent advances on reversible dynamic covalent chemistry (DCC) has attracted great attention to this field. By virtue of thermodynamically controlled equilibria, DCC has provided highly efficient and versatile synthetic routes in the selection of specific products from a complex system. Among the several reversible reactions in the category of DCC reactions, the imine formation has proven to be very versatile in macrocyclization to give complex interlocked molecular compounds. Cryptands are three dimensional bicyclic hosts with preorganized cavities capable of inclusion of ions and small molecules. Replacing the nitrogen bridgeheads in common cryptands with aromatic ring systems gives cyclophane-based macrobicycles. The introduction of aromatic ring systems into a preorganized cage-like geometry facilitates ion-{pi} interactions and …
Date: April 30, 2009
Creator: Klivansky, Liana M.; Koshkakaryan, Gayane; Cao, Dennis & Liu, Yi
System: The UNT Digital Library
Neutron Energy Measurements in Radiological Emergency Response Applications (open access)

Neutron Energy Measurements in Radiological Emergency Response Applications

We present significant results in recent advances in the determination of neutron energy. Neutron energy measurements are a small but very significant part of radiological emergency response applications. Mission critical information can be obtained by analyzing the neutron energy given off from radioactive materials. In the case of searching for special nuclear materials, neutron energy information from an unknown source can be of paramount importance.
Date: April 30, 2009
Creator: Sanjoy Mukhopadhyay, Paul Guss, Michael Hornish, Scott Wilde, Tom Stampahar, Michael Reed
System: The UNT Digital Library
OPTIMIZATION STUDIES FOR THE ADVANCED PHOTOINJECTOR EXPERIMENT (APEX) (open access)

OPTIMIZATION STUDIES FOR THE ADVANCED PHOTOINJECTOR EXPERIMENT (APEX)

The Advanced Photoinjector Experiment (APEX) seeks to validate the design of a proposed high-brightness, normal conducting RF photoinjector gun and bunching cavity feeding a superconducting RF linac to produce nC-scale electron bunches with sub-micron normalized emittances at MHz-scale repetition rates. The beamline design seeks to optimize the slice averaged 6D brightness of the beam prior to injection into a high gradient linac for further manipulation and delivery to an FEL undulator. Details of the proposed beamline layout and electron beam dynamics studies are presented.
Date: April 30, 2009
Creator: Lidia, S.M.
System: The UNT Digital Library
Analytic Solution of the Envelope Equations for an Undepressed Matched Beam in a FODO Quadrupole Channel (open access)

Analytic Solution of the Envelope Equations for an Undepressed Matched Beam in a FODO Quadrupole Channel

In 1958, Courant and Snyder analyzed the problem of alternating-gradient beam transport and treated a model without focusing gaps or space charge. Recently we revisited their work and found the exact solution for matchedbeam envelopes in a linear quadrupole lattice [O.A. Anderson and L.L. LoDestro, Phys. Rev. ST Accel. Beams, 2009]. We extend that work here to include the effect of asymmetric drift spaces. We derive the solution and show exact envelopes for the first two solution bands and the peak envelope excursions as a function of the phase advancesigma up to 360o. In the second stable band, decreased occupancy requires higher focus field-strength and accentuates the remarkable compression effect predicted for the FD (gapless) model.
Date: April 29, 2009
Creator: Anderson, Oscar & LoDestro, L. L.
System: The UNT Digital Library
Cyclotron Resonances in Electron Cloud Dynamics (open access)

Cyclotron Resonances in Electron Cloud Dynamics

A new set of resonances for electron cloud dynamics in the presence of a magnetic field has been found. For short beam bunch lengths and low magnetic fields where lb<< 2pi c/omega c (with lb = bunch length, omega c = non-relativistic cyclotron frequency) resonances between the bunch frequency and harmonics of the electron cyclotron frequency cause an increase in the electron cloud density in narrow ranges of magnetic field near the resonances. For ILC parameters the increase in the density is up to a factor ~;;3, and the spatial distribution of the electrons is broader near resonances, lacking the well-defined vertical density"stripes" found for non-resonant cases. Simulations with the 2D computer code POSINST, as well as a single-particle tracking code, were used to elucidate the physics of the dynamics. The existence of the resonances has been confirmed in experiments at PEP-II. The resonances are expected to affect the electron cloud dynamics in the fringe fields of conventional lattice magnets and in wigglers, where the magnetic fields are low. Results of the simulations and experimental observations, the reason for the bunch-length dependence, and details of the dynamics are discussed here.
Date: April 29, 2009
Creator: Celata, C. M.; Furman, Miguel A.; Vay, J. L.; Ng, J. S. T.; Grote, D. P.; Pivi, M. T. F. et al.
System: The UNT Digital Library
FULL ELECTROMAGNETIC SIMULATION OF FREE-ELECTRON LASER AMPLIFIER PHYSICS VIA THE LORENTZ-BOOSTED FRAME APPROACH (open access)

FULL ELECTROMAGNETIC SIMULATION OF FREE-ELECTRON LASER AMPLIFIER PHYSICS VIA THE LORENTZ-BOOSTED FRAME APPROACH

Numerical simulation of some systems containing charged particles with highly relativistic directed motion can by speeded up by orders of magnitude by choice of the proper Lorentz-boosted frame[1]. A particularly good example is that of short wavelength free-electron lasers (FELs) in which a high energy electron beam interacts with a static magnetic undulator. In the optimal boost frame with Lorentz factor gamma_F , the red-shifted FEL radiation and blue shifted undulator have identical wavelengths and the number of required time-steps (presuming the Courant condition applies) decreases by a factor of 2(gamma_F)**2 for fully electromagnetic simulation. We have adapted the WARP code [2]to apply this method to several FEL problems involving coherent spontaneous emission (CSE) from pre-bunched ebeams, including that in a biharmonic undulator.
Date: April 29, 2009
Creator: Fawley, William M & Vay, Jean-Luc
System: The UNT Digital Library
High Average Power Lasers for the Photon Collider (open access)

High Average Power Lasers for the Photon Collider

The idea to convert an electron collider into a high energy photon collider has existed for several decades. A key technological limitation to realizing this idea is the need to create a large amount of laser power to drive the Compton back-scattering. A concept to reduce the required laser power using a recirculating cavity has been proposed. We describe a concept for a laser architecture that could drive such a cavity.
Date: April 29, 2009
Creator: Stuart, B; Gronberg, J & Seryi, A
System: The UNT Digital Library
PREPARATIONS FOR ASSEMBLY OF THE INTERNATIONAL ERL CRYOMODULE AT DARESBURY LABORATORY (open access)

PREPARATIONS FOR ASSEMBLY OF THE INTERNATIONAL ERL CRYOMODULE AT DARESBURY LABORATORY

The collaborative development of an optimised cavity/cryomodule solution for application on ERL facilities has now progressed to final assembly and testing of the cavity string components and their subsequent cryomodule integration. This paper outlines the verification of the various cryomodule sub-components and details the processes utilised forfinal cavity string integration. The paper also describes the modifications needed to facilitate this new cryomodule installation and ultimate operation on the ALICE facility at Daresbury Laboratory.
Date: April 29, 2009
Creator: McIntosh, P. A.; Bate, R.; Beard, C. D.; Cordwell, M. A.; Dykes, D. M.; Pattalwar, S. M. et al.
System: The UNT Digital Library
Prototype Vector Machine for Large Scale Semi-Supervised Learning (open access)

Prototype Vector Machine for Large Scale Semi-Supervised Learning

Practicaldataminingrarelyfalls exactlyinto the supervisedlearning scenario. Rather, the growing amount of unlabeled data poses a big challenge to large-scale semi-supervised learning (SSL). We note that the computationalintensivenessofgraph-based SSLarises largely from the manifold or graph regularization, which in turn lead to large models that are dificult to handle. To alleviate this, we proposed the prototype vector machine (PVM), a highlyscalable,graph-based algorithm for large-scale SSL. Our key innovation is the use of"prototypes vectors" for effcient approximation on both the graph-based regularizer and model representation. The choice of prototypes are grounded upon two important criteria: they not only perform effective low-rank approximation of the kernel matrix, but also span a model suffering the minimum information loss compared with the complete model. We demonstrate encouraging performance and appealing scaling properties of the PVM on a number of machine learning benchmark data sets.
Date: April 29, 2009
Creator: Zhang, Kai; Kwok, James T. & Parvin, Bahram
System: The UNT Digital Library
R&D Toward a Neutrino Factory and Muon Collider (open access)

R&D Toward a Neutrino Factory and Muon Collider

There is considerable interest in the use of muon beams to create either an intense source of decay neutrinos aimed at a detector located 3000-7500 km away (a Neutrino Factory), or a Muon Collider that produces high-luminosity collisions at the energy frontier. R&D aimed at producing these facilities has been under way for more than 10 years. This paper will review experimental results from MuCool, MERIT, and MICE and indicate the extent to which they will provide proof-of-principle demonstrations of the key technologies required for a Neutrino Factory or Muon Collider. Progress in constructing components for the MICE experiment will also be described.
Date: April 29, 2009
Creator: Zisman, Michael S.
System: The UNT Digital Library
TUNABLE TENSOR VOTING FOR REGULARIZING PUNCTATE PATTERNS OFMEMBRANE-BOUND PROTEIN SIGNALS (open access)

TUNABLE TENSOR VOTING FOR REGULARIZING PUNCTATE PATTERNS OFMEMBRANE-BOUND PROTEIN SIGNALS

Membrane-bound protein, expressed in the basal-lateral region, is heterogeneous and an important endpoint for understanding biological processes. At the optical resolution, membrane-bound protein can be visualized as being diffused (e.g., E-cadherin), punctate (e.g., connexin), or simultaneously diffused and punctate as a result of sample preparation or conditioning. Furthermore, there is a significant amount of heterogeneity as a result of technical and biological variations. This paper aims at enhancing membrane-bound proteins that are expressed between epithelial cells so that quantitative analysis can be enabled on a cell-by-cell basis. We propose a method to detect and enhance membrane-bound protein signal from noisy images. More precisely, we build upon the tensor voting framework in order to produce an efficient method to detect and refine perceptually interesting linear structures in images. The novelty of the proposed method is in its iterative tuning of the tensor voting fields, which allows the concentration of the votes only over areas of interest. The method is shown to produce high quality enhancements of membrane-bound protein signals with combined punctate and diffused characteristics. Experimental results demonstrate the benefits of using tunable tensor voting for enhancing and differentiating cell-cell adhesion mediated by integral cell membrane protein.
Date: April 29, 2009
Creator: Loss, Leandro; Bebis, George & Parvin, Bahram
System: The UNT Digital Library
ALTERNATE APPROACH TO HAZARD CATEGORIZATION FOR SALTSTONE FACILITY AT SRS (open access)

ALTERNATE APPROACH TO HAZARD CATEGORIZATION FOR SALTSTONE FACILITY AT SRS

The Saltstone Facility at Savannah River Site (SRS) was originally segmented into two segments: the Saltstone Production Facility (SPF) and the Saltstone Disposal Facility (SDF). Based on the inventory of radionuclides available for release the SPF and SDF were categorized as Nonreactor Hazard Category (HC)-3. The hazard categorization recognized the SDF will contain contributions of radionuclides which would exceed the HC-2 Threshold Quantity (TQ) in the form of grout. However it was determined not to impact the facility hazard categorization based on the grout being in a solid, monolithic form which was not easily dispersible. But, the impact of a quantity of unset grout expected to be present at the vault following operation of the process was not addressed. A Potential Inadequacy in Safety Analysis (PISA) was later issued based on the hazard categorization determination for the facility not addressing unset grout. This initiated a re-evaluation of the accident scenarios within the hazards analysis. During this re-evaluation, the segmentation of the facility was challenged based on the potential interaction between facility segments; specifically, the leachate return line and the grout transfer line, which were considered separate segments, are located in close proximity at one point. such that for certain events …
Date: April 28, 2009
Creator: Roy, B.
System: The UNT Digital Library
Designing Neutralized Drift Compression for Focusing of Intense Ion Beam Pulses in a Background Plasma (open access)

Designing Neutralized Drift Compression for Focusing of Intense Ion Beam Pulses in a Background Plasma

Neutralized drift compression offers an effective method for particle beam focusing and current amplification. In neutralized drift compression, a linear radial and longitudinal velocity drift is applied to a beam pulse, so that the beam pulse compresses as it drifts in the drift-compression section. The beam intensity can increase more than a factor of 100 in both the radial and longitudinal directions, resulting in more than 10,000 times increase in the beam number density during this process. The self-electric and self-magnetic fields can prevent tight ballistic focusing and have to be neutralized by supplying neutralizing electrons. This paper presents a survey of the present theoretical understanding of the drift compression process and plasma neutralization of intense particle beams. The optimal configuration of focusing and neutralizing elements is discussed in this paper.
Date: April 28, 2009
Creator: Kaganovich, I. D.; Davidson, R. C.; Dorf, M.; Startsev, E. A.; Barnard, J. J.; Friedman, A. et al.
System: The UNT Digital Library
Limits on a muon flux from neutralino annihilations in the Sun with the IceCube 22-string detector (open access)

Limits on a muon flux from neutralino annihilations in the Sun with the IceCube 22-string detector

A search for muon neutrinos from neutralino annihilations in the Sun has been performed with the IceCube 22-string neutrino detector using data collected in 104.3 days of live-time in 2007. No excess over the expected atmospheric background has been observed. Upper limits have been obtained on the annihilation rate of captured neutralinos in the Sun and converted to limits on the WIMP-proton cross-sections for WIMP masses in the range 250-5000 GeV. These results are the most stringent limits to date on neutralino annihilation in the Sun.
Date: April 28, 2009
Creator: Collaboration, IceCube & Klein, Spencer
System: The UNT Digital Library
California Wintertime Precipitation in Regional and Global Climate Models (open access)

California Wintertime Precipitation in Regional and Global Climate Models

In this paper, wintertime precipitation from a variety of observational datasets, regional climate models (RCMs), and general circulation models (GCMs) is averaged over the state of California (CA) and compared. Several averaging methodologies are considered and all are found to give similar values when model grid spacing is less than 3{sup o}. This suggests that CA is a reasonable size for regional intercomparisons using modern GCMs. Results show that reanalysis-forced RCMs tend to significantly overpredict CA precipitation. This appears to be due mainly to overprediction of extreme events; RCM precipitation frequency is generally underpredicted. Overprediction is also reflected in wintertime precipitation variability, which tends to be too high for RCMs on both daily and interannual scales. Wintertime precipitation in most (but not all) GCMs is underestimated. This is in contrast to previous studies based on global blended gauge/satellite observations which are shown here to underestimate precipitation relative to higher-resolution gauge-only datasets. Several GCMs provide reasonable daily precipitation distributions, a trait which doesn't seem tied to model resolution. GCM daily and interannual variability is generally underpredicted.
Date: April 27, 2009
Creator: Caldwell, P M
System: The UNT Digital Library
LITERATURE SURVEY OF GASEOUS HYDROGEN EFFECTS ON THE MECHANICAL PROPERTIES OF CARBON AND LOW ALLOY STEELS (open access)

LITERATURE SURVEY OF GASEOUS HYDROGEN EFFECTS ON THE MECHANICAL PROPERTIES OF CARBON AND LOW ALLOY STEELS

Literature survey has been performed for a compendium of mechanical properties of carbon and low alloy steels following hydrogen exposure. The property sets include yield strength, ultimate tensile strength, uniform elongation, reduction of area, threshold stress intensity factor, fracture toughness, and fatigue crack growth. These properties are drawn from literature sources under a variety of test methods and conditions. However, the collection of literature data is by no means complete, but the diversity of data and dependency of results in test method is sufficient to warrant a design and implementation of a thorough test program. The program would be needed to enable a defensible demonstration of structural integrity of a pressurized hydrogen system. It is essential that the environmental variables be well-defined (e.g., the applicable hydrogen gas pressure range and the test strain rate) and the specimen preparation be realistically consistent (such as the techniques to charge hydrogen and to maintain the hydrogen concentration in the specimens).
Date: April 27, 2009
Creator: Lam, P; Andrew Duncan, A; Robert Sindelar, R & Thad Adams, T
System: The UNT Digital Library
Resonant Kicker System Development at SLAC (open access)

Resonant Kicker System Development at SLAC

The design and installation of the Linear Coherent Light Source [1] at SLAC National Accelerator Laboratory has included the development of a kicker system for selective beam bunch dumping. The kicker is based on an LC resonant topology formed by the 50 uF energy storage capacitor and the 64 uH air core magnet load which has a sinusoidal pulse period of 400us. The maximum magnet current is 500 A. The circuit is weakly damped, allowing most of the magnet energy to be recovered in the energy storage capacitor. The kicker runs at a repetition rate of 120Hz. A PLC-based control system provides remote control and monitoring of the kicker via EPICS protocol. Fast timing and interlock signals are converted by discrete peak-detect and sample-hold circuits into DC signals that can be processed by the PLC. The design and experimental characterization of the system are presented.
Date: April 27, 2009
Creator: Beukers, Tony; Krzaszczak, John; Larrus, Marc & Lira, Antonio de
System: The UNT Digital Library