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Sarah Rogers ISIS Facility, Rutherford Appleton Laboratory, UK
Neutrons for Science
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Neutrons for Science
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Neutrons
Where atoms are...
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...and what they do
Neutrons
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Neutron Properties
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H
X - rays
neutrons
Cs Zr Mn S O C Li Cs Zr Mn S O Li
X - rays
neutrons
Neutron Properties
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H
X - rays
neutrons
Cs Zr Mn S O C Li Cs Zr Mn S O Li
X - rays
neutrons
Neutron Properties
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~ 2000 users/yr ~450 publications/yr ~ 800 experiments/yr
90% of UK Users 5/5* Departments
World leading expertise and instrumentation in the application of
neutrons to condensed matter science
Access Mechanisms Direct access Rapid access Xpress Programme access Commercial ICRD scheme
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Spallation Neutrons
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Accelerator Driven Neutron Source (Spallation)
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High Energy
Protons
Target 2
Target 1
Accelerator Driven Neutron Source (Spallation)
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The collision of high energy protons with the tungsten nuclei releases neutrons
15-20 neutrons
High energy Proton
excited nucleus
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Energy (eV) 109 106 103 100 10-3 10-6
Spallation
epi-thermal hot
thermal cold
ultra-cold
Electronic transitions Molecular vibrations
Sound modes Diffusion
10-6 10-4 10-2 100 102 10-5 10-3 10-1 101
Wavelength (nm)
Excitations
Lattice spacing Polymers and bio-molecules
Structure
𝜆 =ℎ
𝑚𝑣
Moderators
𝜆 = 1.798 Å 𝐸 = 25.3 𝑚𝑒𝑉 𝑣 = 2.20 𝑘𝑚/𝑠 𝑇 = 293𝐾
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Neutron Source
Sample
Neutron Detector
Dis
tance
Time
Time-of-flight
L2
2θ
L1
𝑣 = 𝐿1 + 𝐿2 𝑡
𝐸 =1
2𝑚𝑣2 𝑛𝜆 = 2𝑑 sin 𝜃 𝜆 =
ℎ
𝑚𝑣
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Neutron Diffraction and Imaging
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Specification: imaging
Cold (hydrogen) moderator
Typical L/D values: 250 – 500
Max. Field of View: 20x20 cm2
Best spatial resolution: 50 μm
Energy resolution: λ/λ
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Neutron Source
Sample
Neutron Detectors
L1 = 50m
Gauge volume
Radial collimator
Diffraction
Further info: Shu Yan Zhang – [email protected]
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No stress 200MPa uniaxial stress
d-spacing (Angstrom)
d-spacing (Angstrom)
𝑠𝑡𝑟𝑎𝑖𝑛 𝜀 =(𝑑 − 𝑑0)
𝑑0
No stress 200MPa uniaxial stress
𝑛𝜆 = 2𝑑 sin 𝜃
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Neutron Source Sample
L1
Neutron Imaging Detector
Neutron Imaging: Measure the transmitted beam: what is not scattered or absorbed
𝜎𝑡𝑜𝑡𝑎𝑙 = σ 𝑐𝑎𝑝𝑡𝑢𝑟𝑒 + 𝜎 𝐵𝑟𝑎𝑔𝑔 +⋯
Imaging
Further info: Winifried Kockelmann – [email protected]
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Neutron Imaging Neutron cross sections gives unique view
Oil flow in engine, imaged at FRM-II neutron source
Neutron Source Sample
L1
Neutron Imaging Detector
𝜎𝑡𝑜𝑡𝑎𝑙 = σ 𝑐𝑎𝑝𝑡𝑢𝑟𝑒 + 𝜎 𝐵𝑟𝑎𝑔𝑔 +⋯
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How does localised deformation modify fluid flow in porous rock? Use of neutron radiography to monitor water imbibition into a sample of a sandstone with localised deformation features
Neutron radiography X-ray radiography
Sandstone sample
Why Neutrons?
The large neutron scattering cross section of hydrogen means that water/oil scattering can be distinguished clearly from the rock
Flat
ten
ed s
urf
ace
Flattened
surface
Oil invaded rock
Data from ILL
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Results
Start
Transmitted neutron intensity
Low High
End
Velocity
/ mm/s
0 0
0 0
0.00
0.08
0.04
450
250 250
450
Tracked flow-fronts over
final neutron radiograph Flow velocities
Geophys. Res. Letts. 2013, 40, 2613-2618
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Neutron & Nanometers
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Neutron Source
q
Sample
Scattered beam Scattering vector, Q
Source
L1 L2
Incident beam
Lengthscales, 10’s to 100’s nm are explored in reciprocal space by detecting the scattered neutrons around the forward direction at small angles.
𝐼 𝑄 = 𝜌𝑃 − 𝜌𝑀2𝑁𝑃𝑉𝑃
2𝑃 𝑄 S 𝑄
Structure factor: inter-particle information. Depends on the type of interactions in the system. S(Q) = 1 for dilute dispersions
Form factor: intra-particle information - size and shape of particle
Cross sectional contrast
Allows the investigation of bulk properties of a material: Size Polydispersity Shape/Structure Particle Interaction
Small-Angle Neutron Scattering (SANS)
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Where Q is inversely proportional to distances within the sample, D, by the approximation:
𝑄 =2𝜋
𝑑
Q is also related to wavelength and the scattering angle by: 𝑄 =4𝜋sin 𝜃 2
𝜆
Units are either Å-1 or nm-1 i.e. the smaller the value of Q the bigger the object
Neutron Source
q
Sample
Scattered beam Scattering vector, Q
Source
L1 L2
Incident beam
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The Science
Typical month on Sans2d!
• Chemists
Colloidal crystals
Micellization in unusual solvents – sc-CO2 and ILs
Templating of nanoparticles with micelles and microemulsions
• Industry
Fuel additives
In-situ rheology of industrially relevant polymer systems
Interaction of perfumes with micelles
• Biologists
Solution scattering
Growth of fibrils
• Pharmacists
Movement of drugs through and into vesicle bilayers
• Polymer scientists
Interfacial structure of polymers at solid-liquid interfaced via GISANS
Polymer structure in solution
• Physicists
Structural and magnetic scattering from super spin glasses
0.1
0
-0.1
0.05
-0.05
Qy
/ Å
-1
0.1 0 -0.1 0.05 -0.05
Qx / Å-1
Key
= contrast 1 e.g.
deuterated
= contrast 2 e.g.
hydrogenated
Shell contrast Drop contrast Core contrast
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0.001
0.01
0.1
1
10
100
1000
10
100
1000
0.01
0.1
I(Q
) /
cm
-1
Time /
s
Q / Å -1
15 s
30 s
45 s
75 s
105 s
165 s
225 s
345 s
465 s
705 s
945 s
1425 s
1905 s
The Sample Environment
Extensive available sample environments allow a broad range of science to be studied via SANS at ISIS
• Sample changer
• Tumblers
• Rheometer
• Pressure cells
• T-jump cell
• Furnace
• Cryostat
• Magnets
• In situ DLS and UV-vis
• Stopped-flow (see figure)
Synchronized data collection
event mode allows data to be time sliced after the experiment
Micelles Bilayer disks Vesicle
Time
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D
X - rays
neutrons
Cs Zr Mn S O C Li Cs Zr Mn S O Li
X - rays
neutrons
Nuclear Interaction
Changes
H
isotopes
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Neutron Beam
Pump
Sapphire Windows Stirrer
Viscosity Modifiers
J. Eastoe (University of Bristol) & R. Enick (University of Pittsburgh) Langmuir 2010, 26(1), 83-88
•Studying the use of high pressure CO2 for
enhanced oil recovery using dedicated 600 bar
pressure cell
•Low viscosity of CO2 promotes fingering through
porous media rather than a uniform sweep
•Modifiers commonly used in oily solvents are
incompatible with CO2. Can self assembled
custom-made surfactants be used?
•Yes! Altering the counterion of the surfactant from
Na to Ni or Co causes a viscosity enhancement of
up to 90% compared to pure CO2.
•Why? Neutrons have the answer! Use D2O for
contrast
Na+ or Co2+n(D2O)
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•Understanding the physics of flowing colloidal
particles is important for many industrial processes
•Here near monodisperse 0.14 micron diameter
polystyrene particles at 8% in water crystallise into
domains a few mm in size.
•By rotating and rocking the colloidal crystal in the
neutron beam the nature of the packing (fcc, hcp,
bcc) and stacking faults can be revealed.
•Data was collected to very small Q at 12m sample
to detector on Sans2d with neutrons of wavelength
1.75 to 12.5Å.
Crystallography with 0.14 micron “atoms” A.Rennie & M.Hellsing (Uppsala)
Beam normal to cell Rotate 30° Tilt 12.5° Rotate 45°
SANS from 8% particles
Dilute 0.5% particles,
1mM NaCl, fit
R=720Å
FCC
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0.01
0.1
1
10
0.1
1
10
100
1000
0.01
0.1
I(Q
) /
cm
-1
Time /
s
Q / Å -1
0.5 s
4 s
16 s
64 s
128 s
256 s
512 s
768 s
1024 s
Motor Motor Motor Motor
Mixer
Mixer Mixer
Delay line Delay line
S1 S3 S2 S4
Neutrons Detection
Cuvette
Exit
•Stability and mixing mechanisms are important in
many processes
•Stopped-flow + SANS allows us to probe
nanoscale structural changes on the timescale of
ms to hours
•T-O-F SANS is ideal for these measurements as a
large lengthscale range can be studied in one shot
•Data collection is synchronized with the kit and
automatic cycling is used to improve statistics
•Event mode has now been commissioned on
Sans2d – each neutron has it’s own time stamp
and so data can be ‘time sliced’ after the
measurement has been taken – first time slice
here is 0.5s
•Test system studied: AOT + NaCl and shows a
micelle to vesicle transition
Time Resolved Measurements I. Grillo (ILL) & S. Rogers (ISIS)
Langmuir 2003, 19, 4573-4581
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Structure of Pin-a in Solution
L. Clifton (ISIS-STFC) & R. Frazier et al (University of Reading) PCCP 2011, 26, 8881-8888
W
40.4 Å
112 Å
W
W WW
W
W
W
W
W
W
W
W
W
W
W W
+β
-Pth
+P
in-a
W
W
W
W W
+β
-Pth
+P
in-a
W
W
W
W W
+β
-Pth
+P
in-a
W
W
W
W W
+β
-Pth
+P
in-a
W
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Thanks for listening! Questions?