Recent advances in home construction methods have made considerable progress in addressing energy savings issues. Certain methods are potentially capable of tightening the building envelope, consequently reducing air leakage and minimizing heating and air conditioning related energy losses. Insulated concrete form (ICF) is an economically viable alternative to traditional woodframe construction. Two homes, one of wood-frame, the other of ICF construction, were studied. Standard air leakage testing procedures were used to compare air tightness characteristics achieved by the two construction types. The ICF home showed consistently lower values for air leakage in these tests. The buildings otherwise provided similar data during testing, suggesting that the difference in values is due to greater airtight integrity of the ICF construction method. Testing on more homes is necessary to be conclusive. However, ICF construction shows promise as a tighter building envelope construction method.

The cAMP-dependent protein kinase (PKA) is a multifunctional kinase that serves as a prototype for understanding second messenger signaling and protein phosphorylation. In the absence of a cAMP signal, PKA exists as a dimer of dimers, consisting of two regulatory (R) and two catalystic (C) subunits. Based on experimentally derived data (i.e., crystal structures of the R and C subunits, mutagenesis data identifying points of subunit-subunit contacts), the neutron scattering derived model for the heterodimer (Zhao et al., 1998) and using a set of computational approaches (homology modeling, Monte Carlo simulation), they have developed a high-resolution model of the RII{alpha}-C{alpha} dimer. The nature of the subunit-subunit interface was studied. The model reveals an averaged size dimer interface (2100 Angstrom{sup 2}) that is distant from the pseudo-substrate binding site on the C subunit. The additional contacts made by the pseudosubstrate increases the stability of the dimeric complex. Based on a set of R-C dimer structures derived using a simulated annealing approach, specific interactions (hydrogen bonds) between the two subunits and were identified.

Diameter effect and front curvature measurements are reported for rate stick experiments on commercially available prilled ANFO (ammonium-nitrate/fuel-oil) at ambient temperature. The shots were fired in paper tubes so as to provide minimal confinement. Diameters ranged from 77 mm ({approx} failure diameter) to 205 mm, with the tube length being ten diameters in all cases. Each detonation wave shape was fit with an analytic form, from which the local normal velocity Dn, and local total curvature {kappa}, were generated as a function of radius R, then plotted parametrically to generate a Dn({kappa}) function. The observed behavior deviates substantially from that of previous explosives, for which curves for different diameters overlay well for small {kappa} but diverge for large {kappa}, and for which {kappa} increases monotonically with R. For ANFO, we find that Dn({kappa}) curves for individual sticks (1) show little or no overlap--with smaller sticks lying to the right of larger ones, (2) exhibit a large velocity deficit with little {kappa} variation, and (3) reach a peak {kappa} at an intermediate R.

This paper presents a probabilistic approach for assessing the design and safety of an HSLA-100 Steel Confinement Vessel for particular types of detonations. Likelihood of failure for three different scenarios is considered. They are the likelihood a fragment, (1) penetrates half the containment vessel's thickness, (2) perforates through the containment vessel, and (3) perforates a secondary safety vessel given it's perforated the containment vessel. Uncertainties to be quantified include a fragment's geometry, orientation, and velocity. The governing equation for the likelihood of failure is the probability a large enough fragment exits, that it travels fast enough, and is in the proper orientation. The mathematical formulation of this probability expression is presented. The likelihood of failure is based on existing experimental evidence, theory, and expert judgment. Simulations are performed using Monte Carlo and Latin Hypercube sampling. The assessment model is used to verify and validate numerical predictions in the well-defined-well-documented, (WDWD) domain. Using Bayesian methods, confidence in numerical predictions is assessed within the WDWD domain so inferences beyond the domain can be made with confidence using only numerical analysis. The assessment model's influence diagram is evolved into a decision analysis model. Validation problems are presented to exercise the decision model.

A heatpipe-cooled fast reactor concept has been under development at Los Alamos National Laboratory for the past several years, to be used as a power source for nuclear electric propulsion (NEP) or as a planetary surface power system. The reactor core consists of an array of modules that are held together by a core lateral restraint system. Each module comprises a single heatpipe surrounded by 3-6 clad fuel pins. As part of the design development and performance assessment activities for these reactors, specialized methods and models have been developed to perform thermal and stress analyses of the core modules. The methods have been automated so that trade studies can be readily performed, looking at design options such as module size, heatpipe and clad thickness, use of sleeves to contain the fuel, material type, etc. This paper describes the methods and models that have been developed, and presents thermal and stress analysis results for a Mars surface power system and a NEP power source.

The Advanced Accelerator Applications (AAA) Program was initiated in fiscal year 2001 (FY-01) by the U.S. Congress, the U.S. Department of Energy (DOE), and the Los Alamos National Laboratory (LANL) in partnership with other national laboratories. The primary goal of this program is to investigate the feasibility of transmutation of nuclear waste. An Accelerator-Driven Test Facility (ADTF), which may be built during the first decade of the 21st Century, is a major component of this effort. The ADTF would include a large, state-of-the-art charged-particle accelerator, proton-neutron target systems, and accelerator-driven R&D systems. This new facility and its underlying science and technology will require a large cadre of educated scientists and trained technicians. In addition, other applications of nuclear science and engineering (e.g., proliferation monitoring and defense, nuclear medicine, safety regulation, industrial processes, and many others) require increased academic and national infrastructure and student populations. Thus, the AAA Program Office has begun a multi-year program to involve university faculty and students in various phases of the Project to support the infrastructure requirements of nuclear energy, science and technology fields as well as the special needs of the DOE transmutation program. In this paper we describe university programs that have supported, are …

Experimental measurements and flow visualization of synthetic jets and similar continuous jets are described. The dimensionless stroke length necessary to form a 2-D synthetic jet is between 5 and 10, with wider-nozzle jets consistently requiring a smaller value. Synthetic jets are wider, slower and have more momentum than similar continuous jets. Synthetic jets are generated using four nozzle widths that vary by a factor of four, and the driving frequency is varied over an order of magnitude. The resultant jets are in the range 13.5 < L{sub o}/h < 80.8 and 695 < Re{sub Uo} < 14700. In spite of the large range of stroke lengths, the near-field behavior of the synthetic jets scales with L{sub o}/h.

The existence of mesoscale stress and velocity fluctuation has been recognized by experimentalists and theoretical analysts. Good examples are stress fields around crack tips and in composite materials. However, the issue of heterogeneous and nonequilibrium shock-front dynamics on the grain scale has been largely ignored, in spite of the fact that they must strongly influence the processes such as shear banding, fracture, and phase transition occurring under the above conditions. These phenomena are governed by the interaction of shock wave with local material properties, crystal anisotropy effects, and microstructure, as well as the nature of interfacial boundaries. The traditional diagnostics including VISAR have not been capable of providing spatially resolved information about the nonuniformity of shock dynamics at the grain level. A possible exception in the mid-80's is that of Mescherykov and his associates who quantified the fluctuations in terms of particle velocity dispersion [1]. New emerging measurements that have requisite spatial and time resolutions do indeed exhibit nonequilibrium fluctuations [2]. The purpose of this study is to extend an earlier numerical simulation where we have observed turbulent like velocity fields as well as velocity dispersion in shock compression of polycrystalline copper [3]. The calculated velocity dispersion was comparable to …

Liquid lead-bismuth (Pb-Bi) eutectic (LBE) may see extensive use as a coolant fluid, and perhaps also as a spallation target, in next generation nuclear energy systems. While it is not as reactive as alkali metal liquids, it does present a long term corrosion problem with some materials, notably stainless steels. Mitigation of the corrosion problem may be achieved by producing and maintaining a protective oxide on exposed surfaces, through control of the concentration of dissolved oxygen in the LBE. We have developed an oxygen sensor based on available zirconia-based solid electrolytes used in the automotive industry, which represents a relatively inexpensive source of reproducible and reliable components. We will present the design considerations and characteristics of our sensor unit, and describe its use in the LBE test loop at Los Alamos for measurement and control of dissolved oxygen concentration.

A new skid-mounted tomographic gamma scanner (TGS) was designed to assist in the decommissioning of Rocky Flats Building 37 1, This instrument was used to assay pyrochemical salts as a prerequisite for disposal at the Waste Isolation Pilot Plant (WIPP). The following paper discusses measurement challenges and results from the first year of operation of the instrument.

Lunar Prospector epithermal neutron data were studied to evaluate the probable chemical state of enhanced hydrogen, [H], reported previously to be near both lunar poles [1,2]. Improved versions of thermal and epithermal neutron data were developed for this purpose. Most important is the improved spatial resolution obtained by using shortened integration times. A new data set was created, Epi* = [Epithermal - 0.057 x Thermal], to reduce effects of composition variations other than those due to hydrogen. The Epi* counting rates are generally low near both lunar poles and high over terrane near recent impact events such as Tycho and Jackson. However, other lunar features are also associated with high Epi* rates, which represent a wide range of terrane types that seem to have little in common. If we postulate that one property all bright Epi* features do have in common is low [H], then measured Epi* counting rates appear to be quantitatively self consistent. If we assume that [H]=O above the top 98th percentile of Epi* counting rates at 2{sup o} x 2{sup o} spatial resolution, then [H]{sub ave} = 55 ppm for latitudes equatorward of [75{sup o}]. This value is close to the average found in returned lunar …

A strong, fast, transverse instability has long been observed at the Los Alamos Proton Storage Ring (PSR) where it is a limiting factor on peak intensity. Most of the available evidence, based on measurements of the unstable proton beam motion, is consistent with an electron-proton two-stream instability. The need for higher beam intensity at PSR and for future high-intensity, proton drivers has motivated a multi-lab collaboration (LANL, ANL, FNAL, LBNL, BNL, ORNL, and PPPL) to coordinate research on the causes, dynamics and cures for this instability. Important characteristics of the electron cloud were recently measured with retarding field electron analyzers and various collection electrodes. Suppression of the electron cloud formation by TiN coatings has confirmed the importance of secondary emission processes in its generation. New tests of potential controls included dual harmonic rf, damping by higher order multipoles, damping by X,Y coupling and the use of inductive inserts to compensate longitudinal space charge forces. With these controls and higher rf voltage the PSR has accumulated stable beam intensity up to 9.7 {micro}C/pulse (6x1013 protons), which is a 60% increase over the previous maximum.

The crystal structure of the recently discovered heavy-fermion (HF) superconductor CeCoIn{sub 5} (T{sub c} = 2.3 K) has been determined by high-resolution neutron powder diffraction. It is tetragonal (space group P4/mmm), with lattice parameters a = 4.61292(9) {angstrom} and c = 7.5513(2) {angstrom} at ambient conditions. Whereas CeCoIn{sub 5} is isostructural with the HF aniferromagnet CeRhIn{sub 5} and the HF superconductor CeIrIn{sub 5}, its cell constants and its only variable positional parameter, zIn2, differ significantly from the corresponding ones of CeRhIn{sub 5} and CeIrIn{sub 5}. As a result, the distortions of the cuboctahedron [CeIn{sub 3}], which is the key structural unit in all three materials, are different in CeCoIn{sub 5} from the ones in CeRhIn{sub 5} and CeIrIn{sub 5}. The compounds CeCoIn{sub 5} and CeIrIn{sub 5}, which contain the most distorted (in one or another way) [CeIn{sub 3}] cuboctahedra exhibit superconductivity at ambient pressure below 2.3 K and 0.4 K, respectively. On the other hand, CeRhIn{sub 5}, in which [CeIn{sub 3}] cuboctahedra are the less distorted, and the cubic HF CeIn{sub 3} are antiferromagnets at ambient pressure with T{sub N} = 3.8 K and 10 K respectively; they become superconductors under pressure of 16 kbar and 25 kbar with T{sub …

The Spallation Neutron Source (SNS) project incorporates a superconducting radio-frequency (SRF) accelerator for the final section of the pulsed mode linac. Cavities with geometrical {beta} values of {beta}=0.61 and {beta}=0.81 are utilized in the SRF section, and are constructed out of thin-walled niobium with stiffener rings welded between the cells near the iris. The welded titanium helium vessel and tuner assembly restrains the cavity beam tubes. Cavities with {beta} values less than one have relatively steep and flat side-walls making the cavities susceptible to Lorentz force detuning. In addition, the pulsed RF induces cyclic Lorentz pressures that mechanically excite the cavities, producing a dynamic Lorentz force detuning different from a continuous RF system. The amplitude of the dynamic detuning for a given cavity design is a function of the mechanical damping, stiffness of the tuner/helium vessel assembly, RF pulse profile, and the RF pulse rate. This paper presents analysis and testing results to date, and indicates areas where more investigation is required.

Using a variety of in situ monitors and when possible adsorption-controlled growth conditions, layered oxide heterostructures including new compounds and metastable superlattices have been grown by reactive molecular beam epitaxy (MBE). The heteroepitaxial layers grown include Bi{sub 4}Ti{sub 3}O{sub 12}-SrTiO{sub 3} and Bi{sub 4}Ti{sub 3}O{sub 12}-PbTiO{sub 3} Aurivillius phases, Sr{sub n+1}Ti{sub n}O{sub 3n+1} Ruddlesden-Popper phases, and metastable PbTiO{sub 3}/SrTiO{sub 3} and BaTiO{sub 3}/SrTiO{sub 3} superlattices. Accurate composition control is key to the controlled growth of such structures, and to this end combinations of reflection high-energy electron diffraction (RHEED), atomic absorption spectroscopy (AA), a quartz crystal microbalance (QCM), and adsorption-controlled growth conditions were employed during growth. The structural perfection of the films has been investigated using in situ RHEED, four-circle x-ray diffraction, atomic force microscopy (AFM), and high-resolution transmission electron microscopy (TEM).

We continue our investigation of the implicit turbulence modeling property of the nonoscillatory finite volume scheme MPDATA. We start by comparing MPDATA simulations of decaying turbulence in a triply periodic cube with analogous pseudospectral studies. In the regime of direct numerical simulation, MPDATA is shown to agree closely with the pseudospectral model. As viscosity is reduced, the two model results diverge. We study the MPDATA results in the inviscid limit, using a combination of mathematical analysis and computational experiment. We validate the inviscid MPDATA results as representing the turbulent flow in the limit of very high Reynolds number.

Over the past dozen years or so there have been significant advances in electron accelerators designed specifically for radiography of hydrodynamic experiments. Accelerator technology has evolved to accomodate the radiographers' contitiuing quest for multiple images in t h e and space:, improvements in electron beam quality have resulted in smaller radiographic spot sizes for better resolution, while higher radiation do% now provides imprcwed penetration of large, dense objects. Inductive isolation and acceleration techniques have played a ley rob in these advances.

A brief review of some of the arguments pointing towards the possibility of organic conductors of the form {alpha}-(BEDT-TTF)&J3g(SCN)4 (where M=K, T1 and Rb) being candidates for Frohlich superconductivity is given.

The transport properties of the semimetallic quasi-onedimensional S= 1/2 antiferromagnet Yb,As, have been studied by performing low-temperature (T 2 0.02 K) and high magnetic field (B I 60 T) measurements of the electrical resistivity p(T,B). For T 2 2 K a 'heavy fermion' like behavior AAT = AT' with huge and nearly field-independent coefficient A 3 3UuRcmK' is observed, whereas at lower temperatures p(r) deviates from this behavior and slightly increases to the lowest T. In B 0 and T L 6 K the resistivity shows an anomalous magnetic-history dependence together with an unusual relaxation behavior. In tht isothermal resistivity Shubnikov-de Haas oscillations, arising fiom a low-density system of mobile As-+ holes, with a frequency of 25 T have been recorded. From the T- and B-dependence of the SdH oscillations an effective carrier mass of (0.275 f 0.O05)ni0 and a charge-camtr mean-free path of 2 15 A are determined. Furthermore in B 2 15 T the system is near the quantum limit and spin-splitting effects are observed.

Pinhole aperture point backlighter (PAPBL) imaging has been used on experiments on Omega, but results have been compromised by large backgrounds. This technique has advantages over traditional area backlighting/pinhole imaging, and the Omega experiments could benefit from this capability, but Omega time is expensive and not the place for developing diagnostic techniques if they can be developed on Trident instead. PAPBL, shot from Direct Drive Cylinder Mix experiments on Omega (DDCYLMIX 00-1, January 18 and 19, 2000). [See LA-UR-00-4187, Post-Shot Report, Direct Drive Cylinder Mix]. In this campaign, they used Trident to obtain clean PAPBL images. Having accomplished that, they attempted to replicate the noise environment of Omega by producing hot electrons and having them impinge on material to produce high-energy x-rays similar to those that might be produced by hot electrons impinging on diagnostics or target positioner components on Omega. Backlighter target design was based, to some degree, on that shown by Bullock et al. at the 42nd Annual APS-DPP Meeting in Quebec City, Quebec, Canada, October 23-27, 2000. [A.B. Bullock et al., Bull. Am. Phys. Soc. 45,(7) 359 (2000); A.B. Bullock et al., Rev. Sci. Instrum. 72, 690 (2001).] We accomplished this to some degree and then attempted, …

The work is aimed at measurements and computer simulations of independent and cumulative yields of residual product nuclei in thin targets relevant as target materials and structure materials for hybrid accelerator-driven systems coupled to high-energy proton accelerators.

An RGIPM has been designed1, constructed and bench tested to verify that all components are functioning properly and that the desired resolution of about 50 {micro}m rms can be achieved. This paper will describe major considerations that went into the bench test and some results.

The n+p{yields}d+{gamma} experiment measures the parity-violating directional gamma-ray asymmetry, A{gamma}, with uncertainties of 0.5x10{sup -8} when cold polarized neutrons are captured by para-hydrogen. This precision measurement will determine the long-range pion-nucleon weak coupling constant, H{sub {pi}}{sup 1}, with a precision of 10% of its predicted value, and thus will help to clarify our understanding of the weak interaction between nucleons. The n+p{yields}d+{gamma} experiment on the SNS beamline 14B is designed to take advantage of the high intensity of the source and its pulsed nature. The experiment requires a 30-Hz pulsed beam for optimal performance. In three months of run time the experiment will achieve a statistical uncertainty of 0.5x10{sup -8}.

Using recent infrasonic data (1995-2001) and older infrasonic data recorded by AFTAC (1960-1974), we have refined our estimates of the global influx rate (cumulative influx) of large bolides with sufficient strength to deeply penetrate the atmosphere (below {approx} 50 km). The number of bolides arriving as a function of their initial source energy has been estimated from a least-squares curve-fit of our database of 19 bolides (for a source energy > 0.053 kt) with the resulting values and an estimate of the associated statistical counting errors: 30.3{+-} 6 bolides at {ge}0.1 kt, 5.8{+-} 2 at {ge}1 kt and 0.84{+-} 0.25 at {ge}15 kt. In this work we also used these estimates to infer the recurrence interval for energy levels slightly outside the original source energy range, The Tunguska bolide of 1908 ({approx}10 Mt) is a prime example of a previously observed body of great interest. Almost regardless of how we analyze the recent data, the conclusion is that bolides with Tunguska type energy levels should reoccur on the average every 120{+-}10 years.