A cylindrical sapphire filter 5.3 cm long (4.3 cm diameter) was added to the shutter. This modification reduced the number of fast neutrons by a factor of five and greatly reduced the low-energy gamma-ray background. The gamma-ray background measured at the perimeter of the apparatus has decreased by a factor of two and the peak-to-background ratios for gamma-ray energies below 500 keV increased by a factor of two to three. The design of the new system is complete. The steel component of the old beam stop will be replaced by aluminum to eliminate iron capture gamma-ray background. The external beam tube will be evacuated to minimize neutron scattering and capture in air and will be constructed from aluminum tubing lined internally with lithoflex to eliminate the background for boron determinations. The detection system will consist of a 40 % (relative efficiency) germanium detector with a bismuth germanate Compton suppression system. The new system will decrease analysis times and improve detection for most elements determined. SAMPLE ENVIRONMENT TEAM Fiscal year 2000 marked the creation of a new Sample Environment Team, dedicated to providing a central resource for the sample environment needs of neutron researchers. This team provides a single contact point to resolve any issue related to the sample condi tions during an experiment, such as temperature, pressure, magnetic field, electric field, or in situ measurements. The scope of this team includes sample preparation and mounting, equipment scheduling, special equipment configurations, operational procedures, provision of necessary resources, sample storage, and equipment repair. Figure 4 shows researchers loading a sample. In this case a difficult SANS experiment was made possible by the team working with the researchers to choose the appropriate sample environment equipment and operating procedures. The most visible change during FY2000 is in the high-bay sample preparation area at the NCNR. This area was extensively remodeled to provide more workspace, greater ease of use, more convenient preparation of cryogenic equipment, and better access to sample storage. Additionally, extensive documentation is now available for the most widely used sample environment equipment, the closed-cycle helium refrigerators. This documentation details individually-measured operating characteristics, sample mounting information, temperature sensor data, and operating guidelines. Significant new equipment acquired for the user community in FY2000 is listed in Table 1. RESEARCH TITLES MATERIALS SCIENCE/CRYSTALLOGRAPHY Ab-Initio Structure Solution of Complex Oxides Using Neutron and X-ray Powder Diffraction Data P. Woodward129 and P. Underwood129 A Bond-Valence Analysis of the Structure of YBa,Fe,0, 1. Natali Sora173 and A. Santoro 105 Aerogels Investigated by SANS with Contrast Masking Solutions Characterization of Ag and Mixed Li/Ag Faujasite Zeolites Using N. Hutson202, R. Yang202, B. A. Reisner 105, and B. H. Toby105 Chemical Ordering in Ni-Mn-Ga Heusler Alloys R. Overholser 199, M. Wuttig 199, and D. A. Neumann 105 Comparison of Residual Stress Measurement Techniques T. Gnäupel-Herold199 105, P. C. Brand105, H. J. Prask105, S. Spooner127, B. Pardue 161, D. Nelson156, and S. Foss70 'CONV' and 'STRESS': New Codes for Data Reduction in Neutron Diffraction Residual Stress Measurements P. C. Brand 105 and T. Gnäupel-Herold 199, 105 Crystal Chemistry of Protonic Centers in Zeolites D. H. Olson210 and B. H. Toby105 Crystal Structure of Ba,CaCu,O,(CO2) Q. Z. Huang199, 105 and F. Izumi95 Crystal Structure of Dehydrated LaD-LSX D. H. Olson210, B. A. Reisner105, and B. H. Toby105 Crystal Structure Determinations of the CeMnO, Compound W.-C. Li94 Defect Structure of (Cu, Zn)InSe, B. A. Reisner 105, M. Knox178, A. Stacy178, and G. Ron178 The Development of Capabilities for the Determination of Residual Stress on the Mesoscale H. J. Prask105, P. C. Brand 105, T. Gnäupel-Herold 199, 105, D. Balzar112, D. Hurley112, and G. Alers112 Development of a Standard for Residual Stress Measurements as Part of VAMAS T. Gnäupel-Herold 199 105, P. C. Brand 105, H. J. Prask105, and G. A. Wester56 Diffraction Elastic Constants for Arbitrary Specimen and Crystal Symmetries: Theory and Practical Consequences T. Gnäupel-Herold 199, 105 and H. J. Prask 105 Distribution of Hydrogen in LaNi, and LaNi,.,Sn, 5-x B. Fultz18, C. K. Witham 18, T. Udovic105, and R. Bowman 18 Effect of Annealing on ZrO, Phase Composition J. K. Stalick 105 and J. Ilavsky29 The Effect of Texture on Elastic Constants H. Sitepu157 105 148, T. Gnäupel-Herold 199 106, J. Matejicek64, R. Fields 113, and H. J. Prask 105 The Effect of Texture on Rietveld Refinement of Powder Diffraction Data of Molybdite and Calcite H. Sitepu157 105 148, T. Gnäupel-Herold199, 105, and H. J. Prask 105 Ethylene Sorption by Copper Aluminum Chloride R. Sullivan 121, J. Martin 121, H. Liu157, and C. Grey157 Exploration of Fe Disproportionation in Ba,Fe0, Grazing Incidence SANS From Plasma Sprayed Coatings A. J. Allen 109and H. Boukari109 Hybridized Epoxy-Silicate Nanocomposites N. Beck-Tan, S. Young, and S. F. Trevino9. 105 Internally Oxidized Palladium Alloys: Particle Size Determination by SANS J. G. Barker105 and T. B. Flanagan221 Investigation of the Zr,Pt,, Structure Type J. K. Stalick 105 and R. Waterstrat105 In Situ Neutron Reflectivity Measurements of Deuterium Absorption in Pd Films B. J. Heuser195, A. Munter 105, N. Barber195, J. A. Dura105, and C. F. Majkrzak 105 Magnetic Cluster Sizes in Thin Film Magnetic Recording Disks M. Toney55, S. M. Choi199, 105, and C. J. Glinka105 Magnetism in Layered Manganates M. A. Green147 Measurement and Modeling of Residual Stresses in Multi-Pass T. Gnäupel-Herold199. 105, H. J. Prask105, R. Lloyd56, and W. Reuter56 Microstructure Evolution of Fly Ash Blended Cements A. J. Allen 109 and R. A. Livingston39, and W. Bumrongiaroen39 Morphological and Kinetic Study of Early Calcium-Silicate-Hydrate Gel Negative Thermal Expansion in AOPO, Compounds Neutron Diffraction of Heusler Alloys V. G. Harris 101 and Q. Z. Huang199 105 Neutron Diffraction of Single-Wall Carbon Nanotubes P. Papanek210, 105, J. E. Fischer210, Z. Benes210, D. Colbert145, and M. Heben145 Neutron Diffraction Study of Copper(I)-Zirconium(IV) Chlorides A. Dattelbaum121, J. Martin121, and B. A. Reisner105 A New Double-Focusing Monochromator for "DARTS" J. H. Scott119, M. E. McHenry19, Z. Turgut 19, and M. Storch19 J. K. Stalick 105, A. Slifka112, and D. Balzar112 Phase Composition Analysis of Plasma-Sprayed Partially Stabilized H. Sitepu157 148 105, H. J. Prask 105, J. K. Stalick 105, R. Goswani 157, and S. Polymerized Fullerenes S. F. Trevino 105, N. Beck-Tan, and L. Balogh89 Pore Structure in Novel Ultra-Low Dielectric Constant Thin Films Residual Stress Determination by Whole Pattern Analysis-Application Residual Stresses in Thermally-Sprayed Coatings J. Matejicek64, T. Gnäupel-Herold 199 105, P. C. Brand:05, H. J. Prask105, H. SANS From Lithographically Patterned Polymer Thin Films SANS Study of Anisotropic Microstructure in Plasma-Spray Coatings SANS Study of Deuteride Formation and Decomposition in Palladium SANS Study of Fire Retardant Polymer-Clay Nanocomposites SANS Study of Nucleation of Aluminum Hydroxide J. Watson, R. Knott, and M. Y. Lin37, 105 Structure Refinements of Alumo- and Gallo-Germanates Using Neutron Scattering Techniques S. Park 157, J. B. Parise157, and B. H. Toby105 Structure Refinement of a Ferromagnetic Vanadium(III) Sulfate D. Grohol, D. Nocera83, B. H. Toby105, and Q. Z. Huang199. 105 Structure of 75.25:24.75 Ca0-Nb,0, J. Chan109, 1. Levin109, R. Roth 109, T. Vanderah109, and B. A. Reisner105 Structure of Sr, 875 DY1.125 Cu20, Q. Z. Huang199, 105 and W. Wong-Ng109 Structures of Ba, Sr,,Coo, Compounds 0.8 0.2 Q. Z. Huang 199, 105 and R. J. Cava140 P. Woodward132, J. Goldberger 132 and P. N. Santosh132 Synthesis, Structure and Electronic Properties of LaCa,Mn,0, M. A. Green147 and D.A. Neumann 105 Thermal Expansion of Alpha SiC From 15 to 298K R. Reeber121.7, K. Wang121, and B. H. Toby105 Thermal Expansion of HgSe R. Reeber121.7 and K. Wang121 Thermal Expansion of II-VI Semiconductors R. Reeber121.7 and K. Wang121 Texture Characterization in X-ray and Neutron Powder Diffraction Data Using the Generalized Spherical-Harmonic H. Sitepu157, 105, 148, H. J. Prask105, and M. D. Vaudin 109 Texture Determination of (CF2), Films Using Neutron Diffraction H. Sitepu157 105, 148, T. Gnäupel-Herold199, 105, J. D. Barnes115, and H. J. Prask 105 Texture Determination of NAFION Using Neutron Diffraction H. Sitepu157 105, 148, T. Gnäupel-Herold 199, 105, S. F. Trevino9 105, and H. J. Prask 105 Texture in Plasma-Sprayed Coatings H. Sitepu157, 105, 148, T. Gnäupel-Herold 199 105, S. Sampath 157, and H. J. Prask105 Texture and Residual Stresses in Hydroformed Aluminum Tubing T. Gnäupel-Herold199 105, H. J. Prask105, and K. N. Shah3 POLYMERS Aggregation of Fullerene-Based Star-lonomers M. P. Nieh137, S. K. Kumar 137, R. M. Briber 199, and L.-T. Ho199 105 L.-T. HO199, 105, R. M. Briber199, and C. J. Glinka105 Compatibility of Polyelastomers D. Peiffer37, M. Y. Lin37, 105, and Y. Zhang157 Critical Neutron Reflection Tests of Polymer Interdiffusion Dynamics R. P. Wool190, K. A. Welp 190, and W. Dozier 190 Dendrimer Like Vesicles S. F. Trevino9, 105 Dynamics of Polymer Interdiffusion S. K. Satija105 Effects of Clay on the Phase Behavior of Polystyrene/PVME Blends Effects of Substrate Interactions on the Ordering of Block Copolymer E. Huang201, J. DeRouchey201, and T. P. Russell201 Effects of Supercritical CO2 on the Phase Behavior of Block Copolymer Melts J. Watkins201, M. Pollard201, G. Brown201, S. Kumar137, and T. P. Russell201 Electric Field-Induced Orientation of Diblock Copolymers in Thin Films J. DeRouchey201 and T. P. Russell201 Hybrid Nanostructures With Hydrophobically Modified Dendrimers Inelastic Neutron Scattering From Filled Elastomers A. I. Nakatani115, R. D. Ivkov105, P. Papanek210, 105, H. Yang154, and M. Interdiffusion of Cross Linked Polymer Films U. Perez-Salas 199, R. M. Birber199, M. Rafailovich 157, J. Sokolov157, and N. F. Berk 105 Investigation of the Concentration Profile Between Cross Linked Thin Films R. M. Briber199, U. A. Perez-Salas 199, M. Rafailovich 157, and J. Sokolov157 In Situ Study of Molecular Conformation in Elastomeric Polypropylene in Uniaxial Extension A. Gast 156 and J. Pople156 Liquid Crystal Polymers in a Magnetic Field M. Dadmun218, W. Burghardt124, and N. Vaish Low Energy Excitations in Deuterated Polystyrene Melt Blended Polymer-Clay Nanocomposites Membrane Mediated Polymer Interdiffusion Microstructure and Properties of Hyperbranched Polymers N. Wagner190 and Y. Kim34 Morphological Study of Comb Copolymer Pervaporation Membranes A. Mayes 83, A. Akthakul83, and Y.-Y. Won83 Multi-Dendrimer Nanostructures F. Groehn115, E. Amis115, and B. J. Bauer115 Neutron Reflectivity From the Monolayers of SAN Random Copolymers E. Kim53, H. Kim, K. Char153, and S. -H. Lee153 105 Neutron Studies of Polymer Dynamics in Intercalated Polymer-Clay Nanocomposites R. D. Ivkov115, P. M.Gehring 105, N. Maliszewskyj105, P. Papanek210, 105, and R. Order-Disorder Transition in Highly Asymmetric Block Copolymers Phase Behavior of Confined Polymer Films S. K. Kumar137, R. Jones 137, L.-T. Ho199, 105, and R. Briber199 J. Watkins 201, G. Brown201, V. Ramachandra Rao201, B. Vogt201, and T. P. Phase Behavior of Pentablock Copolymers F. Bates203, T. Lodge203, X. Wang203, Y. Chen203, and C. Hardy203 Phase Separation in Polyolefin Blends M. Modi 194 and R. Krishnamoorti194 Phase Transitions in Multicomponent Polymer Blends Polyethylene/Polymethylene Blends: Wetting and Phase Transitions Polymer Brushes Under Shear R. D. Ivkov 105, P. D. Butler 105, 127, and S. K. Satija105 Polymer Interdiffusion Near the Polymer/Solid Interface E. K. Lin115, D. J. Pochan190, W.-L. Wu115, S. K. Satija105, and R. Kolb37 Polymer Liquid-Crystal Ordering at an Interface G. Lynn218, E. K. Lin115, W.-L. Wu115, and M. Dadmun218 Polymer Supercritical Fluid Solutions M. McHugh227, T. diNoia, J. vanZanten", C. Kirby, T. Kermis", and S. Conroy71 Polyolefin Polymer Blend Tie Chain Structures D. Lohse37, R. Garner37, and M. Xenidou37 Pressure Dependence of Phase Behavior in Styrene/N-alkyl A.-V. Ruzette83, P. Banerjee83, and A. Mayes83 Pressure Effects on the Aggregation of lonomers D. Perahia25, T. Hill25 and X. Jiao25 SANS Investigations on a New Class of Nylon-6 Polymers SANS Study of Ionomer Blends R. Tucker189, R. Weiss 189, and C. C. Han115 SANS Study of Phase Separation in Model Polymer Networks Shear Induced Polymer Desorption E. K. Lin115, R. Kolb115, and W.-L. Wu115 Shear-Induced Polymer Melt Desorption From an Attractive Solid Surface E. K. Lin115, D. J. Pochan190, W.-L. Wu115, S. K. Satija105, and R. Kolb37 Small Angle Neutron Scattering of Water Dispersable Arborescent Graft Copolymers S. Yun 199, R. M. Briber199, M. Gauthier225, and B. J. Bauer115 Solution Properties of Dendrimer-Like Star Polymers A. Gast156 and J. Pople156 Solvent Vapor Induced Swelling of a Polymer Brush S. K. Satija 105, R. D. Ivkov 105, P. D. Gallagher 105, and J. A. Dura105 Spinodal Decomposition in PS/PI Blends H. Jinnai76, M. Hayashi76, and C. C. Han115 Strain-Induced Interfacial Fracture Between Epoxy and Silicon Oxide M. Kent152 and W. F. McNamara152 Strained Polymer Networks N. Gilra28, C. Cohen28, R. M. Briber199, and T. Panagiotopolis 199 The Structure of Associative Polymers at Rest and Under Shear X. Meng140, 1. Goldmints 140, and W. Russel140 Structure of Filled Elastomer Thin Films Y. Zuang157, B. Tan157, M. Rafailovich 157, J. Sokolov157, and M. Y. Lin37, 105 Structure of Fluorosilicone Networks F. Horkay46 and E. Geissler192 Structure of Nafion in Various Solvents S. F. Trevino9. 105, S. Young, and N. Beck-Tan Surface Segregation in Binary Blends of Topologically Distinct Polymers M. D. Foster176, C. C. Greenberg176, and D. M. Teale176 Structure and Aggregation Kinetics of Asphaltenes T. Mason37, M. Y. Lin37, 105, and E. Sirota37 Structure of Adsorbed Polyelectrolyte Multilayer Thin Films Structure and Morphology of Semicrystalline Polymer Thin Films D. J. Pochan190, E. K. Lin115, W.-L. Wu115, S. K. Satija105, C. F. Majkrzak 105, and R. Kolb37 Study of Thermodynamics in Star and Linear Polymers M. Foster176 and T. Zook176 Thermal Expansion and Glass Transition Behavior of Polymer Films: Effect of the Free Surface and Confinement Between Non-Interacting Surfaces D. J. Pochan190, E. K. Lin115, W.-L. Wu115, S. K. Satija105, and S. Z. D. Cheng176 Thermal Expansion and Glass Transition of Thin Polymer Films Sandwiched Between Polymer Layers D. J. Pochan190, E. K. Lin115, and W.-L. Wu115 COMPLEX FLUIDS Effects of Alcohols and Salts on the Structure of Oil-in-Water J. Lettow83, J. Ying83, and C. J. Glinka105 Effect of Shear Combined with a Proximate Surface on Surfactant Sponge Phases and the Sponge to Lamellar Transition W. A. Hamilton 127, P. D. Butler 105, 127, G. Warr217, and L. Porcar127 Electrostatic and Counterion-Specific Effects on Micelle Morphology Probed with SANS L. J. Magid218, P. D. Butler 105, 127, Z. Han218, and X. Xu218 Field Driven Phase Transitions in Monolayers and Bilayers of J. Lipkowski193, J. Majewski80, and G. Smith80 Interactions of Charged Polymerized Rod-Like Micelles With S. M. Choi199, 105 and S. R. Kline105 Influence of Counterion Valence on Domain Size of Polyelectrolyte Solution Y. Zhang115 and E. Amis115 Magnetic Alignment of Discotic Liquid Crystals B. Pate58 and S. M. Choi199, 105 Microemulsion Structure at an Interface G. Warr217, J. Schulz217, P. D. Butler 105, 127, and W. A. Hamilton127 Microstructure of Alkylpolyglucoside Micelles and Microemulsions L. D. Ryan190, D. lanspetro190, C. McKelvey 190, J. Silas 190, and E. W. Kaler190 Octane Wetting of an Air/Water Interface S. Satija 105 and R. D. Ivkov105 Phase Transitions in Ferrofluids W.-L. Lou11, M. Y. Lin37, 105, D. C. Dender105, and J. W. Lynn105 Poiseuille-Flow-Induced Changes in the Structure of Surfactant Micelles L. Walker19, B. Poore19, M. Truong19, and Y. Christanti19 Polymer, Block Copolymer and Clay Solutions Under Shear G. Schmidt115, C. C. Han115, and P. D. Butler 105, 127 Polymerization of Rod-Like Micelles S. Svenson 140, R. Prud'homme140, and P. Peiffer37 Pressure-Induced Swelling of Polymer Micelles in Supercritical Fluids M. McHugh227, T. diNoia11, J. vanZanten71, C. Kirby71, T. Kermis11, and S. Conroy71 SANS Determination of the Persistence Length in Rod-Like Micelles SANS Determination of the Structure of Vitrified Microemulsions B. Wyslouzil231, C. Heath231, K Streletzky231, G. Wilemski205, and R. Strey188 Solution Structure of Novel Polymerizable Surfactants 26 Crystal and Magnetic Structures of La,RuO,, La,Ru2O2 and LaRu2012 Crystal and Magnetic Structures of Sr,Ru2O, and Sr,Ru2010 Crystal and Magnetic Structures of Sr,Fe,CO, Q. Z. Huang199, 105, R. Cava140, R. W. Erwin105, and J. W. Lynn105 Crystal and Magnetic Structures of TbBaCo20, |