An Introduction to Neutron Scattering - Spallation Neutron Source

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Load Sharing in MMCs can also be Measured by Neutron Diffraction • Initial co-deformation results from confinement of W fibers by the Kanthal matrix • Change of slope (125 MPa) is the typical load sharing behavior of MMCs: – Kanthal yields and ceases to bear further load Applied stress [MPa] – Tungsten fibers reinforce and strengthen the composite 50 0 -1000 -500 0 500 1000 1500 2000 2500 3000 400 350 300 250 200 150 100 Kanthal Tungsten Elastic lattice strain [με]
Deformation Mechanism in U/Nb Alloys Atypical “Double Plateau Stress Strain Curve. Applied Stress (MPa) 500 400 300 200 100 Tensile Axis 0 0 0.02 0.04 0.06 Q || -90° Detector U-6 wt% Nb Typical Metal Macroscopic Strain NPD Diffraction Geometry Q ⊥ + 90 ° Detector Diffraction Results • Important Programmatic Answers. 1. Material is Single Phase Monoclinic (a’’). 2. Lack of New Peaks Rules out Stress Induced Phase Transition. 3. Changes in Peak Intensity Indicate That Twinning is the Deformation Mechanism.
Page 1 and 2:
y Roger Pynn Los Alamos National La
Page 3 and 4:
Why do Neutron Scattering? • To d
Page 5 and 6:
The Neutron has Both Particle-Like
Page 7 and 8:
Thermal Neutrons, 8 keV X-Rays & Lo
Page 9 and 10:
Brightness & Fluxes for Neutron & X
Page 11 and 12:
Scattering by a Single (fixed) Nucl
Page 13 and 14:
Coherent and Incoherent Scattering
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so or ie Coherent Elastic Scatterin
Page 17 and 18:
Neutrons can also gain or lose ener
Page 19 and 20:
Magnetic Scattering • The magneti
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Ene rgy Trans fe r (me V) 10000 100
Page 23 and 24:
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
Page 29 and 30:
About 1.5 Useful Neutrons Are Produ
Page 31 and 32: The ESRF* & ILL* With Grenoble & th
Page 33 and 34: Neutron Sources Provide Neutrons fo
Page 35 and 36: Proton Radiography 800-MeV Linear A
Page 37 and 38: Components of a Spallation Source A
Page 39 and 40: Simultaneously Using Neutrons With
Page 41 and 42: The Actual ToF Gain From Source Pul
Page 43 and 44: Why Isn’t There a Universal Neutr
Page 45 and 46: • Uncertainties in the neutron wa
Page 47 and 48: Typical Neutron Scattering Instrume
Page 49 and 50: Most Neutron Detectors Use 3 He •
Page 51 and 52: Rotating Choppers Are Used to Tailo
Page 53 and 54: 3. Diffraction Next Lecture 1. Diff
Page 55 and 56: 2. Diffraction This Lecture 1. Diff
Page 57 and 58: Neutron Diffraction • Neutron dif
Page 59 and 60: For Periodic Arrays of Nuclei, Cohe
Page 61 and 62: We would be better off if diffracti
Page 63 and 64: Powder - A Polycrystalline Mass All
Page 65 and 66: Measuring Neutron Diffraction Patte
Page 67 and 68: Time-of-Flight Powder Diffraction U
Page 69 and 70: There’s more than meets the eye i
Page 71 and 72: How good is this function? Protein
Page 73 and 74: High-resolution Neutron Powder Diff
Page 75 and 76: Texture Measurement by Diffraction
Page 77 and 78: Definitions of Stress and Strain
Page 79 and 80: Why use Metal Matrix Composites ? F
Page 81: Neutron Diffraction Measures Mean R
Page 85 and 86: Obtaining the Pair Distribution Fun
Page 87 and 88: Effect of Doping on the Octahedra
Page 89 and 90: Surface Reflection Is Very Differen
Page 91 and 92: What Is the Neutron Wavevector Insi
Page 93 and 94: Only Those Thermal or Cold Neutrons
Page 95 and 96: What do the Amplitudes a R and a T
Page 97 and 98: Fresnel’s Law for a Thin Film •
Page 99 and 100: Reflection by a Graded Interface io
Page 101 and 102: Direct Inversion of Reflectivity Da
Page 103 and 104: 4 R*Q z 10 -7 10 -8 10 -9 1.3% PEG
Page 105 and 106: Polarized Neutron Reflectometry (PN
Page 107 and 108: Reflection from Rough Surfaces z z
Page 109 and 110: fi fi fi Q =kf -ki Qx-Qz Transforma
Page 111 and 112: Observation of Hexagonal Packing of
Page 113 and 114: This Lecture 5. Small Angle Neutron
Page 115 and 116: Two Views of the Components of a Ty
Page 117 and 118: Where Does SANS Fit As a Structural
Page 119 and 120: Instrumental Resolution for SANS Tr
Page 121 and 122: SANS Measures Particle Shapes and I
Page 123 and 124: 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
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References • Viewgraphs describin
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We Have Seen How Neutron Scattering
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The Elastic & Inelastic Scattering
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Examples of S(Q,ω) and S s(Q,ω)
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Inelastic Magnetic Scattering of Ne
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Measured Inelastic Neutron Scatteri
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Atomic Motions for Longitudinal & T
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Phonons - the Classical Use for Ine
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The Accessible Energy and Wavevecto
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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
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• Uncertainties in the neutron wa
Page 163 and 164:
The Underlying Physics of Neutron S
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How does a Neutron Spin Behave when
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The Principles of NSE are Very Simp
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For Quasi-elastic Scattering, the E
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Neutron counts ( per 50 sec) Neutro
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Field-Integral Inhomogeneities caus
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Neutron Spin Echo study of Deformat
Page 177 and 178:
Neutron Spin Phases NRSE spectromet
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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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