Neutrons in Science

1
Neutrons in Science

• Professor Michael James

2
Research Reactor vs Power Reactor
Power 20 MW 3000 MW Uranium
30 kg 100,000 kg Temperature
60 ?C 100 ?C Uses Generates
neutrons for Generates steam for
Radioisotopes, Si and Science
Electricity
3
Performance of Neutron Scattering at OPAL
Neutron scattering enhanced by 10 - 1000 times
relative to HIFAR
An international scientific user facility
4
Why do ice cubes float?
5
Hydrogen vs Deuterium
electron
proton
neutron
6
OPAL at 20 MW
7
Neutrons Faster than a speeding bullet?
450 m/s
8
Neutron Transport
Neutrons travel 80 m in 0.04 s
9
Neutron Transport
Neutrons in air lose 10 of their intensity per
metre We transmit neutrons under vacuum through
supermirror neutron guides
10
Supermirror Neutron Guides
Supermirror coatings reflect neutrons at
glancing angles (lt 5?).
Transmits neutrons from the reactor to
instruments (like a fibre-optic transmits light)
11
White Beam vs Monochromatic Neutrons
Just like visible light, our white neutron
beams are comprised of a range of wavelengths
12
How do Neutrons Interact with Matter?
Neutrons scatter from an atoms nucleus, not the
electron cloud
13
What Happens When a Neutron Hits Something?
14
What Happens When a Neutron Hits Something?
neutron
Mostly nothing!!!
15
What Happens When a Neutron Hits Something?
16
What Happens When a Neutron Hits Something?
Sometimes, it scatters
17
Elastic Scattering
18
Inelastic Scattering
19
Key Strengths of Neutron Science
20
Key Strengths of Neutron Science
Investigations of atomic structure under extreme
environments
21
Key Strengths of Neutron Science
Studies of Magnetism and Magnetic Materials
22
Key Strengths of Neutron Science
Cell membrane physiology
23
Key Strengths of Neutron Science
Structure and Dynamics of Hydrogen Storage
Materials
24
Key Strengths of Neutron Science
Non-Destructive Testing for Materials Engineering
25
Key Strengths of Neutron Science
Structure and Function in Molecular Biology
26
Key Strengths of Neutron Science
Studies of NanoscaleSoft Condensed Matter
27
Key Strengths of Neutron Science
Food Science
28
Key Strengths of Neutron Science
New Energy Technologies
29
Key Strengths of Neutron Science
Conducting Polymers and Liquid Crystals
30
Lengthscales for Neutron Scattering
Human Hair 100,000 nm
Deposited Nanostructures500 nm
Red Blood Cells7000 nm
Si Atoms0.2 nm
DNA2 nm
Influenza Virus100 nm
31
Why Use Neutrons as a Probe of Atomic and
Nanoscale Structures?
1. Have the right wavelength 2. See the
nuclei not the electron cloud (Contrast between
H and D) 3. See light atoms next to heavy ones
4. Measure the velocity of atoms 5.
Penetrate deeply into matter (Non-destructive)
6. Interacts with magnetic materials
32
Hydrogen Deuterium Contrast What Neutrons See
When the monster came, Lola remained
undetected. Harold, of course, was immediately
devoured.
33
Neutron Instruments at OPAL
Quokka (SANS)
Platypus (Reflectometer)
Wombat (Hi-Intensity Powder)
Koala (Single Crystal)
Pelican (Polarization Spectrometer)
Kowari (Residual Stress)
Sika (Cold TAS)
Kookaburra (USANS)
Echidna (Hi-Resolution Powder)
Taipan (Thermal TAS)
34
Three Axis Spectrometers
Neutron Scattering Instruments at OPAL
Taipan / Sika
NANOSTRUCTURES
Polarization Spectrometer Pelican
Ultra-SANS Kookaburra
High Speed Diffractometer Wombat
High Resolution Diffractometer Echidna
Reflectometer Platypus
Residual Stress Kowari
Quasi-Laue Diffractometer Koala
Small Angle Scattering Quokka
ATOMICSTRUCTURE
35
Atomic Structure Diffraction and Braggs Law
l 2dsinq
q
incoming neutrons
diffracted neutrons
36
Energy TechnologiesCorrelating Properties with
Atomic Structure
Gives the location of light elements such in the
presence of heavy metal atoms.
Battery Materials
Solid Oxide Fuel Cells
Monitoring of atomic structure during device
application.
Hydrogen Storage
37
In-situ Diffraction of Li-ion Battery Cycling
Location and quantity of Li ions can be tracked
duringcharging and discharging.
38
In-situ Diffraction of Li-ion Battery Cycling
Charged
Discharged
39
Hydrogen for Transport
40
Hydrogen Fuel Cells A Much Better Way
41
Hydrogen Storage in Solid Metal-Organic Frameworks

• MOFs consist of metal oxide clusters linked by
  organic molecules
• High surface area
• Crystalline nano-porous material with tunable
  pore size
• Functionality of the linker can also be varied

42
Formation of Methane Hydrates
Wealth From Oceans
43
Non-Destructive Testing of Engineered
MaterialsStress Determination in Crystalline
Materials
Improve the reliability and safety of critical
components
Non-destructive mapping of mechanical stresses.
Welds, joints, hardening, quenchingMetals,
alloys and compositesFrom the production line
or after use.
44
What Happens When Pipelines Get Stressed
45
What Happens When Pipelines Get Stressed
predicted stress
measured stress in weld
400 kg branch section
critical crack size is increased by a factor of
3. Unnecessary weld repairs are avoided
46
Neutrons and Nanotechnology
Materials used in countless industrial
preparations are based on molecular
nano-composites
Stabilised Polymer Emulsions
47
Understanding Biological Signaling
If DNA damage is detected, Sda binds
to Histidine Kinase (KinA), preventing it from
initiating a phosphorelay
Protein Kinases Regulate the majority of cellular
pathways, especially those involved in signal
transduction Up to 30 of all proteins may be
modified by kinase activity
A. E. Whitten, D. A. Jacques, et al. J. Molecular
Biology 368, 407 (2007).
48
Neutron Reflectometry
Depth profiling of nanoscale systems with atomic
resolution Film thickness (1 nm - 100 nm) Film
composition Hydration of surface
coatings Molecular self-assembly Biological
structure and function
49
Enzyme-Membrane Interactions(Death by Cobra)
Neutron reflectometry allows us to observe
molecular interactions with biomimetic cell
membranes
Studies of disease mechanisms cholera,
diphtheria, Alzheimers, pneumonia,
50
Magnetic Thin Film Memory
Data in modern digital devices is stored on
nanoscale magnetic thin films
Neutrons can probe both structure and magnetism
in thin films
51
Explosive Sensing Using Dendrimer Films
Centre for Organic Photonics and Electronics (U.
Queensland)
52
Better Than X-ray Vision...(Neutron Radiography)
Penetrating ability of neutrons is sensitive to
different nuclei
53
Better Than X-ray Vision
X-rayRadiography
NeutronRadiography
Neutron radiography is more penetrating and has
better contrast
54

Any Questions? (michael.james_at_ansto.gov.au)
55
(No Transcript)