The PEO-PPO-PEO triblock copolymers have important applications in industry and medicine. Because of the differing solubilities of PEO and PPO in water, these copolymers exhibit a rich phase behavior that is sensitive to polymer concentration, solvent ionic strength, temperature, and pressure. These phase changes occur by the self-assembly of the polymer chains into structures with characteristic length scales most appropriately measured in nanometers. Thus, small-angle neutron scattering (SANS) is a probe uniquely well-suited to studying this phase behavior. In these experiments we will probe the effects of concentration and ionic strength on block copolymer self-assembly using solutions of 1,2, and 5 weight% Pluronics F108 triblock copolymer in D20 with varying concentrations of salt added, one series in which the anion is the same and the cation is varied, and another where the reverse is true. The size morphology, and aggregation number of the micellar structures will be extracted through nonlinear least-squares fitting of the scattering data to model functions.

Small-angle neutron scattering (SANS) is a powerful tool for looking at the conformation of biological macromolecules in solution. SANS is particularly sensitive to conformational changes of proteins and nucleic acids in response to applied stimuli, such as temperature, pressure or small molecules. We will study the solution conformation of human serum albumin, a multifunction protein found in the blood, and how it changes in response to urea, a protein denaturant, using the BioSANS instrument at HFIR. Various methods of fitting the data will be employed to extract the molecular weight of the scattering particle, the radius of gyration, the distance distribution function P(r) and the maximum linear dimension. Methods for developing models of the protein from SANS data will also be discussed.

Fe-Ga alloys with appropriate composition and heat treatment, exhibit giant magnetostriction in a polycrystalline and ductile form.1,2 The tetragonal magnetostriction coefficient, 100, of Fe-Ga can be up to 15 times that of pure Fe. This makes these materials of tremendous scientific interest as well as technological interest for use in devices such as actuators, transducers and sensors. Elastic constant measurements3 show that the shear elastic constant 1/2(C11-C12) decreases with increasing Gallium concentration and extrapolates to zero at approximately 26 at.% Ga. The slope of the phonon dispersion curve at low-q of the T2[110] branch is a measure of that elastic constant and hence the interest in measuring phonons in these materials. With the large magnetoelastic interactions in such a material, it is also of interest to measure the spin wave dispersion. In the neutron school experiments at HB1, HB1A and HB3, we will use samples of three compositions of Fe-Ga alloys in to measure both phonon and spin wave neutron groups at room temperature.

Fe-Ga alloys with appropriate composition and heat treatment, exhibit giant magnetostriction in a polycrystalline and ductile form.1,2 The tetragonal magnetostriction coefficient, 100, of Fe-Ga can be up to 15 times that of pure Fe. This makes these materials of tremendous scientific interest as well as technological interest for use in devices such as actuators, transducers and sensors. Elastic constant measurements3 show that the shear elastic constant 1/2(C11-C12) decreases with increasing Gallium concentration and extrapolates to zero at approximately 26 at.% Ga. The slope of the phonon dispersion curve at low-q of the T2[110] branch is a measure of that elastic constant and hence the interest in measuring phonons in these materials. With the large magnetoelastic interactions in such a material, it is also of interest to measure the spin wave dispersion. In the neutron school experiments at HB1, HB1A and HB3, we will use samples of three compositions of Fe-Ga alloys in to measure both phonon and spin wave neutron groups at room temperature.

Neutron powder diffraction combined with quantitative Rietveld analysis is a powerful tool for determining the quantities of crystalline and amorphous components in multiphase mixtures. The experiment is aimed to demonstrate the quantitative phase analysis procedure for the case of manganese molybdate (with the composition MnMoO4) containing manganese oxide (Mn2O3) as an impurity phase. The high resolution diffraction data will be collected at the ambient temperature using the HB2A powder diffractometer at the HFIR. The data analysis will be performed by using the freely distributed program FullProf Suite [1]. 1. The FullProf Suite is available at: http://www.ill.eu/sites/fullprof/.

Neutron diffraction measurements will be performed to investigate the onset of long-range magnetic order in the FeF2 [1-4]. Data will be collected at various temperatures, ranging from 300 K to 5 K, using the Wide-Angle Neutron Diffractometer (WAND) at the HFIR. Rietveld analysis of the crystal and low-temperature magnetic structure will be carried out using FullProf Suite software. The results obtained will be discussed and compared with those reported in earlier studies.

Fe-Ga alloys with appropriate composition and heat treatment, exhibit giant magnetostriction in a polycrystalline and ductile form.1,2 The tetragonal magnetostriction coefficient, λ100, of Fe-Ga can be up to 15 times that of pure Fe. This makes these materials of tremendous scientific interest as well as technological interest for use in devices such as actuators, transducers and sensors. Elastic constant measurements3 show that the shear elastic constant 1/2(C11-C12) decreases with increasing Gallium concentration and extrapolates to zero at approximately 26 at.% Ga. The slope of the phonon dispersion curve at low-q of the T2[110] branch is a measure of that elastic constant and hence the interest in measuring phonons in these materials. With the large magnetoelastic interactions in such a material, it is also of interest to measure the spin wave dispersion. In the neutron school experiments at HB1, HB1A and HB3, we will use samples of three compositions of Fe-Ga alloys in to measure both phonon and spin wave neutron groups at room temperature.

The hydrogen in zirconium hydride (ZrH2) sits at the interstitial positions between the zirconium. At the simplest description, the energy levels can be considered to be the same as a particle in a potential well. The aim of this experiment is to measure the vibrational spectrum of ZrH2 as a function of energy and wavevector transfer, and determine how well it conforms to the predictions of the scattering from a harmonic oscillator. Practical applications of sample preparation, data collection and analysis will be given to generate the scattering function S(Q, ω) from the data. This will be compared to theoretical predictions based on the harmonic oscillator description, with a discussion of what may cause any discrepancies found. As time permits, other metal hydrides will be measured to highlight differences in their energy spectra.

Protic ionic liquids show great potential for mobile fuel cell applications. They possess appealing features such as almost negligible vapor pressure, the characteristic electrical conductivity of an ionic conductor, and a sizable temperature gap between the melting and decomposition points. The diffusion dynamics of protons in these complex liquids are closely tied to their performance as electrolytes. Quasielastic neutron scattering (QENS) is a technique of choice for studying the details of diffusion dynamics of hydrogen because of (1) the large incoherent scattering cross-section of hydrogen compared to other elements and (2) capability of probing spatial characteristics of diffusion processes through dependence of the scattering signal on the momentum transfer, Q. The latter is a clear advantage of QENS compared to, for instance, NMR. In our QENS experiment to be performed on the new SNS backscattering spectrometer, BASIS, we will utilize the Q-dependence of the scattering signal to identify and analyze several dynamic processes involving diffusion motions of hydrogen atoms in a recently synthesized ionic liquid [H2NC(dma)2][BETI].

Students will load a sample of liquid water into a Paris-Edinburgh pressure cell. They'll increase the pressure on the sample first to 1.5 GPa and then to 3 GPa collecting data at each point. Once analyzed, the data will reveal that the sample has undergone two phase transitions: First from liquid water at ambient pressure to ice VI at 1.5 GPa and second from ice VI to ice VII at 3 GPa.

Polarized neutron reflectometry will be applied to study the phase transition in LaMnO3 thin film epitaxially grown on SrTiO3 substrate. Recent studies have shown a strong influence of interfaces on the magnetic properties of complex metal-oxide thin films, leading to behaviors that are radically different from those of bulk materials. This is particularly true for manganites. Our ongoing work on layered films formed of paramagnetic SrTiO3 and antiferromagnetic LaMnO3 shows the occurrence of interface-induced ferromagnetism. With this experiment, students will probe the magnetic structure in films, in order to understand the fascinating effects of layer-layer coupling.

Isotopic substitution is a powerful tool in neutron scattering studies. In this experiment we will observe the self-diffusion of polystyrene (PS) by means of a 500-A-thick deuterated (dPS) layer float-deposited atop a spin-coated 500-A-thick protonated PS layer on a silicon substrate. Students will prepare the film in the beamline 4B wet lab and measure specular reflectivity. We will then anneal the sample for ~30 mins in a vacuum oven and re-measure the reflectivity. Students will fit the data from the two runs to observe changes in the interfacial width of the dPS/PS. We will have backup samples ready in case deposition fails for some reason.