An Introduction to Neutron Scattering - Spallation Neutron Source

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$Powder Diffraction - Spallation Neutron Source$

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The Principle of Neutron Resonant Spin Echo • Within a coil, the neutron is subjected to a steady, strong field, B0, and a weak rf field B1cos(ωt) with a frequency ω = ω0 = γ B0 – Typically, B0 ~ 100 G and B1 ~ 1 G • In a frame rotating with frequency ω 0, the neutron spin sees a constant field of magnitude B 1 • The length of the coil region is chosen so that the neutron spin precesses around B1 thru an angle π. • The neutron precession phase is: φ exit neutron = φ = 2φ exit RF entry RF + ( φ −φ entry RF −φ entry neutron entry neutron ) + ω d / v 0 S entry S B 0 exit S B 1 (t) rotated π exit B 1 entry B 1
Neutron Spin Phases NRSE spectrometer in an NRSE Spectrometer* n B= B=0 ÌÐ ËÔÒ ÓÖÒØØÓÒ ÌÑ Ø È× ¬Ð Ö ÒÙØÖÓÒ ËÔÒ Ô× Ë Ø Ø A B C D B 0 tA tA’ t tB Sample B=0 + + + + + + + + d lAB d d lCD d Ø Ø Ú Ø Ø Ú Ø Ø Ð Ú Ø Ø Ú Ø Ø Ð Ú Ø Ð Ú Ø Ø Ð Ú Ø Ø Ú Ø Ú Ø Ð Ú Ø Ø Ð Ú Ø Ú Ø Ð Ú Ø Ø Ð Ú Ø Ð Ú Ð Ú B 0 B0 B=0 B0 tC tC’ t tD Echo occurs for elastic scattering when l AB + d = l CD + d * Courtesy of S. Longeville
Page 1 and 2:
y Roger Pynn Los Alamos National La
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Why do Neutron Scattering? • To d
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The Neutron has Both Particle-Like
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Thermal Neutrons, 8 keV X-Rays & Lo
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Brightness & Fluxes for Neutron & X
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Scattering by a Single (fixed) Nucl
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Coherent and Incoherent Scattering
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so or ie Coherent Elastic Scatterin
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Neutrons can also gain or lose ener
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Magnetic Scattering • The magneti
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Ene rgy Trans fe r (me V) 10000 100
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References • Introduction to the
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Overview 1. Essential messages from
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What Do We Need to Do a Basic Neutr
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About 1.5 Useful Neutrons Are Produ
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The ESRF* & ILL* With Grenoble & th
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Neutron Sources Provide Neutrons fo
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Proton Radiography 800-MeV Linear A
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Components of a Spallation Source A
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Simultaneously Using Neutrons With
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The Actual ToF Gain From Source Pul
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Why Isn’t There a Universal Neutr
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• Uncertainties in the neutron wa
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Typical Neutron Scattering Instrume
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Most Neutron Detectors Use 3 He •
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Rotating Choppers Are Used to Tailo
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3. Diffraction Next Lecture 1. Diff
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2. Diffraction This Lecture 1. Diff
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Neutron Diffraction • Neutron dif
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For Periodic Arrays of Nuclei, Cohe
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We would be better off if diffracti
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Powder - A Polycrystalline Mass All
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Measuring Neutron Diffraction Patte
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Time-of-Flight Powder Diffraction U
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There’s more than meets the eye i
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How good is this function? Protein
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High-resolution Neutron Powder Diff
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Texture Measurement by Diffraction
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Definitions of Stress and Strain
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Why use Metal Matrix Composites ? F
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Neutron Diffraction Measures Mean R
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Deformation Mechanism in U/Nb Alloy
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Obtaining the Pair Distribution Fun
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Effect of Doping on the Octahedra
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Surface Reflection Is Very Differen
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What Is the Neutron Wavevector Insi
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Only Those Thermal or Cold Neutrons
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What do the Amplitudes a R and a T
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Fresnel’s Law for a Thin Film •
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Reflection by a Graded Interface io
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Direct Inversion of Reflectivity Da
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4 R*Q z 10 -7 10 -8 10 -9 1.3% PEG
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Polarized Neutron Reflectometry (PN
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Reflection from Rough Surfaces z z
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fi fi fi Q =kf -ki Qx-Qz Transforma
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Observation of Hexagonal Packing of
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This Lecture 5. Small Angle Neutron
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Two Views of the Components of a Ty
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Where Does SANS Fit As a Structural
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Instrumental Resolution for SANS Tr
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SANS Measures Particle Shapes and I
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Examples of Spherically-Averaged Fo
Page 125 and 126: Correlations Can Be Measured in Con
Page 127 and 128: Radius of Gyration Is the Particle
Page 129 and 130: Contrast & Contrast Matching Water
Page 131 and 132: Verification of of the Gaussian Coi
Page 133 and 134: Porod Scattering function. n correl
Page 135 and 136: ln(I) Typical Intensity Plot for SA
Page 137 and 138: References • Viewgraphs describin
Page 139 and 140: We Have Seen How Neutron Scattering
Page 141 and 142: The Elastic & Inelastic Scattering
Page 143 and 144: Examples of S(Q,ω) and S s(Q,ω)
Page 145 and 146: Inelastic Magnetic Scattering of Ne
Page 147 and 148: Measured Inelastic Neutron Scatteri
Page 149 and 150: Atomic Motions for Longitudinal & T
Page 151 and 152: Phonons - the Classical Use for Ine
Page 153 and 154: The Accessible Energy and Wavevecto
Page 155 and 156: What Use Have Phonon Measurements B
Page 157 and 158: Time-of-flight Methods Can Give Com
Page 159 and 160: Neutron Spin Echo By Roger Pynn* Lo
Page 161 and 162: • Uncertainties in the neutron wa
Page 163 and 164: The Underlying Physics of Neutron S
Page 165 and 166: How does a Neutron Spin Behave when
Page 167 and 168: The Principles of NSE are Very Simp
Page 169 and 170: For Quasi-elastic Scattering, the E
Page 171 and 172: Neutron counts ( per 50 sec) Neutro
Page 173 and 174: Field-Integral Inhomogeneities caus
Page 175: Neutron Spin Echo study of Deformat
Page 179 and 180: The Measured Polarization for NRSE
Page 181 and 182: Measuring Line Shapes for Inelastic
Page 183 and 184: “Phonon Focusing” • For a sin
Page 185 and 186: An NRSE Triple Axis Spectrometer at
Page 187 and 188: “Tilted” Fields for Diffraction
Page 189 and 190: Spin Echo SANS using Magnetic Films
Page 191: Conclusion: NSE Provides a Way to S
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An Introduction to Neutron Scattering - Spallation Neutron Source

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