Sarah Rogers ISIS Facility, Rutherford Appleton Laboratory, UK

Neutrons for Science

Neutrons for Science

Neutrons

Where atoms are...

...and what they do

Neutrons

Neutron Properties

H

X - rays

neutrons

Cs Zr Mn S O C Li Cs Zr Mn S O Li

X - rays

neutrons

Neutron Properties

H

X - rays

neutrons

Cs Zr Mn S O C Li Cs Zr Mn S O Li

X - rays

neutrons

Neutron Properties

~ 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

Spallation Neutrons

Accelerator Driven Neutron Source (Spallation)

High Energy

Protons

Target 2

Target 1

Accelerator Driven Neutron Source (Spallation)

The collision of high energy protons with the tungsten nuclei releases neutrons

15-20 neutrons

High energy Proton

excited nucleus

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

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

Neutron Diffraction and Imaging

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

Neutron Source

Sample

Neutron Detectors

L1 = 50m

Gauge volume

Radial collimator

Diffraction

Further info: Shu Yan Zhang – shu-yan.zhang@stfc.ac.uk

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

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 – winifried.kockelmann@stfc.ac.uk

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 +⋯

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

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

Neutron & Nanometers

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)

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

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

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

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

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)

•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

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

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

Thanks for listening! Questions?