Inelastic Neutron Scattering
The Study of Lattice Dynamics in Crystalline Material using Inelastic Neutron Scattering
Inelastic neutron scattering is an experimental method that is used to observe and measure the micro-vibration (dynamics) of atoms and spins in a sample material. By observing the difference in energy between the incident and scattered neutrons, the magnitudes, distances, and directions of the forces acting between the atoms or spins in the sample can be determined.
In this course, students will measure atomic vibrations (phonons) in a single crystal by inelastic neutron scattering using the chopper spectrometer 4SEASONS. By analyzing the data, students will learn what kinds of forces act between atoms and how they affect the macroscopic properties.
The Study of Molecular Dynamics on the Nanosecond Timescale using Quasielastic Neutron Scattering
Quasielastic neutron scattering is considered to be one of the most effective techniques for measuring the dissipation motion (e.g. fluctuation or diffusion) of atoms, molecules and spins in a material. In particular, in a number of widely-used functional materials, such as in lithium secondary batteries or fuel cells, solid state ionic conductors play an important role. In these solid state ionic conductors, the ions or hydrogen atoms are moving at a speed similar to that of the liquid state, even at around room temperature. These dynamic motions of ions and hydrogen atoms can be measured at the nanosecond timescale using quasi-elastic neutron scattering.
In this course, students will use the DNA high-resolution spectrometer to study the hydrogen ion dynamics in a Nafion ion exchange membrane, a material that is currently in practical use in polymer electrolyte fuel cells. At the same time, students will learn how to analyze the data from a typical quasielastic neutron scattering experiment.
Study of Spin Dynamics by using Inelastic Neutron Scattering
By using inelastic neutron scattering technique, we can observe motions of atoms and spins (atomic magnets) in a material. Neutron scattering data tell us how these atoms and spins are coupled with each other in the sample. We can extract lots of underlining microscopic information, which is indispensable to material science studies, from the data.
In this course, students will measure the collective motions of spins in a crystalline sample on AMATERAS, a cold-neutron disk-chopper-type inelastic neutron scattering instrument. The students can experience basic of study on spin dynamics in a crystalline system through the experiment on a simple spin system and data analysis.
BL08: SuperHRPD, BL09: SPICA
Decipher the Materials Structure of Interest
We are surrounded by materials with various functions. Functions of batteries, magnets, superconductors, multiferroic materials, optical & thermoelectric materials, soft materials, etc. are consequences of atomic structures & their changes with various characteristic scales.
In this course, we will learn about the method to decipher the atomic structures of functional materials using advanced neutron diffraction techniques. Understanding atomic structures are the first step in materials science. Students will conduct high resolution neutron diffraction experiments using the SuperHRPD diffractometer at the beamline BL08 or the SPICA diffractometer at BL09, and will experience crystallographic analyses and the visualization of the atomic structures.
In-situ High Pressure Neutron Diffraction
Pressurization reduces interatomic distance of materials, which sometimes induces drastic changes in their physical properties. To understand the origin of the changes, its structural information is essential. In-situ high-pressure neutron diffraction is useful for getting the information.
In this course, participants will learn methods to generate pressure and determine crystal structures through in-situ powder neutron experiments of a high-density D2O ice whose structure differs from the normal ice at PLANET beamline.
Materials science and engineering studies using pulsed neutron diffraction in TAKUMI
TAKUMI is a TOF neutron powder diffractometer dedicated for materials science and engineering studies. Careful analysis of the Bragg peaks in a neutron diffraction pattern can reveal important structural details of a sample material such as internal stresses, phase fractions, dislocations, texture etc. Such information is often crucial in engineering applications and the ability to carry out either ex situ or in situ measurements makes neutron diffraction particularly useful in this respect.
In this course, the basics of materials science and engineering studies using neutron diffraction will be introduced and students will participate in trial experiments using TAKUMI and hands-on data analysis sessions. A residual strain mapping in a metallic engineering part (welded steel or rail) will be performed as the trial experiment.
Structural Analysis using the Small and Wide Angle Neutron Scattering Instrument TAIKAN
The small-angle neutron scattering (SANS) method is valuable in characterizing the nanoscale structure of materials. The Small and Wide Angle Neutron Scattering Instrument TAIKAN can probe structures in a sample on a correlation length scale from about 0.1 nm to over about 1,000 nm.
The following topics will be covered in this course:
· SANS measurement using a pulsed beam
· Similarities and differences between SANS using a pulsed beam, SANS using a continuous beam and SAXS
· Diversity of sample environments
· Experimental methods and data analysis procedures using samples such as nanoparticles, polymers, metals, magnetic materials, etc.
BL16: SOFIA, BL17: SHARAKU
Surface and interface analysis using neutron reflectometry
As different materials meet at surfaces and interfaces, they show characteristic properties and various functions due to their peculiarity, which attract chemists, biologists, and physicists. Neutron reflectometry (NR) is a powerful tool for investigating the surface and interfaces of soft matters, magnetic materials etc. on the nanometer to sub-micrometer length scale with taking advantage of the unique characteristics of neutrons. Neutrons can distinguish an interesting part labeled with deuterium and/or can observe an interface between solid and liquid through a substrate. Polarized neutron reflectometry can observe magnetic moment behavior on the surfaces and interfaces of magnetic materials.
In this course, students can choose the NR experiment with non-polarized neutrons using the SOFIA reflectometer or that with polarized neutrons using SHARAKU reflectometer. At the SOFIA, the neutron reflectivity profiles of polymer thin films on Si substrates will be measured in air and in water with different contrasts. At the SHARAKU, the neutron reflectivity profiles of magnetic thin films on Si substrates will be measured in air. The observed reflectivity profiles will be analyzed using the Parratt formalism to determine the change in the structure of the thin films.
The Study of Neutron capture cross section measurements
The neutron capture cross section is a likelihood ratio of a capture reaction between an incident neutron and a target nucleus. It is one of the most important information for nuclear plant designs, and fundamental physics.
In this course, neutron capture cross section measurement of Au will be carried out using the Accurate Neutron-Nucleus Reaction measurement Instrument (ANNRI) at BL04, where they will receive instruction in experiments that offer hands-on learning experiences.
Visualization of Structure and Physical Property Distributions Using Energy-Resolved Neutron Imaging
Neutron imaging is a widely-used, nondestructive investigation method to visualize the internal structure of objects. The energy-resolved neutron imaging technique using a pulsed neutron beam, where the energy dependent neutron transmission is carefully analyzed position by position, provides the spatial distribution of various information, such as elemental concentration and temperature by neutron resonance absorption imaging, crystallographic structure by Bragg-edge imaging, and magnetic field by polarized neutron imaging.
In this course, both conventional neutron imaging and energy-resolved neutron imaging will be introduced. Students will conduct demonstration experiments for both neutron imaging methods using the RADEN instrument (BL22), including data analysis and visualization of the results.
Positive muon spin relaxation (μSR)
Positive muon in a material stops at an interstitial site, observes magnetic fields of the environment and exhibits Larmor spin precession. By measuring the decay positrons emitted from muons, time dependent behavior of the muon spin in a material is known. This is the spectroscopy called (positive) muon spin relaxation (μSR). This technique yields the information of the magnetic property of a material, including magnetism and superconductivity and the hydrogen state in a material with the muon being a light hydrogen isotope.
In contrast to neutron, muon is a local magnetic probe in real space with a unique time scale, being a powerful probe of spin relaxation phenomena.
In this course, students will have an opportunity to actually perform μSR measurement at the S1-ARTEMIS spectrometer and will receive instruction of data analysis. Introductory lectures on μSR and other muon measurements will also be given as a part of the school.
Elemental analysis using negative muon
Negative muon injected in a material, which forms a muonic atom, i.e. a bound state of a muon and a nucleus, is used for non-destructive elemental analysis. The principle for this usage of negative muon is the spectroscopy (energy analysis) of muonic X-rays, which are emitted as the muon cascades down its atomic orbitals. This is the same principle with the characteristic X-ray analysis from electron orbitals, but due to 200 times heavier mass of negative muon, the energy of muonic X-ray is also 200 times higher than that of "electronic" X-ray. For instance, a muonic carbon emits 75 keV X-ray in 2p-1s transition, and this energy is enough high to penetrate out of a material. Tuning the muon energy, the implantation depth of a muon in a material can be controlled, and the elemental composition at the intended depth is determined by detecting muonic X-rays.
In this course, students will have an opportunity to detect muonic X-ray from unknown materials by a germanium detector, and determine the elemental composition non-destructively.