Scattering of Neutrons of Neutrons Scattering Basics Basics - - PDF document

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Scattering of Neutrons of Neutrons Scattering Basics Basics Regine Willumeit Willumeit Regine GKSS Research Center GKSS Research Center 1.11.2010: Helmholtz Zentrum Geesthacht Zentrum fr Material und Kstenforschung How are neutrons

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Scattering Scattering of Neutrons

  • f Neutrons

Basics Basics

Regine Regine Willumeit Willumeit

GKSS Research Center GKSS Research Center

How are neutrons produced? What are the properties of neutrons? The concept of contrast variation Experimental set up of a SANS instrument Data analysis: what is different to X-rays

1.11.2010: Helmholtz Zentrum Geesthacht Zentrum für Material und Küstenforschung

Fission

200 MeV n = 2 MeV Natural abundance 0.71 %

How How are are Neutrons Neutrons Produced Produced? ?

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View View of

  • f the

the FRG1 FRG1

How How are are Neutrons Neutrons Produced Produced? ?

Shut Shut down in down in June June 2010 2010

Reactor hall

warm water

Schematic picture of FRG-1

controll center reactor pool second pool reactor core first cooling system Heat exchanger beryllium reflector beamlines experimental hall second cooling system

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Comparison Comparison Power : Research Power : Research Reactor Reactor

enrichment 3.3-3.5 % <20 % # fuel elements 840 12

  • therm. power

3690 MW 5 MW moderator H2O H2O neutron flux

<< 1014 n/s cm2 1.4x1014 n/s cm2

type pressure swimming-pool fuel UO2 U3Si2 Power Research [Krümmel] [FRG-1]

ILL:  = 1.5*1015 n/s cm2 [Prof R. Scherm]  = 1.5*1021 n/s m2 average speed: v = 2000 m/s

density = /v = 6.8*1017 n/m3 comparison air: p=10-7 mbar!

What What does does the the flux flux mean mean? ?

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Spallation Particles with high energy hit a target neutrons come out

How How are are Neutrons Neutrons Produced Produced? ? SNS SNS

[H-] Protons liquid Mercury 1 GeV H+ 1 Protons -> 20-30 Neutrons

European Spallation Source „ESS-I“

How How are are Neutrons Neutrons Produced Produced? ?

Three sites were competing: Lund (S), Bilbao (E) and Debrecen (H)

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European Spallation Source „ESS-I“

How How are are Neutrons Neutrons Produced Produced? ?

ESS MAX-Lab Malmö

Comparison Comparison of Neutron

  • f Neutron Sources

Sources

ESS

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Correlation Correlation between between Energy and Wave Energy and Wave Length Length

pm pm

Neutron Neutron Properties Properties

no charge

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Neutron Neutron Properties Properties

magnetic moment

Neutron Neutron Properties Properties

Deep Penetration deep inside materials or technical components residual stress, texture, cavities, precipitates, cracks ... Strong Magnetic Interaction magnetic surface and bulk structures ... magnetic structure on atomic scale, domane structures ... Strong Interaction with H2 and D2 surface and bulk structures, ordered layers, solution ... Soft matter research: polymers, colloids, biological macromolecules ... Nuclear Reactions chemical analysis of more than 50 elements in bulk ... -Spectrum => nuclear activation analysis

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Neutrons X-Rays Intensity low high H-sensitivity high none Isotope-sensitivity strong none Heavy elements low high Spin-sensitivity strong average Penetration depth high low Sample size/amount large small Measurement time long short Interaction with nuclei electron shell electron shell unsystematic  Z Radiation damage none high

To To Remember Remember: :

Interaction of Interaction of Radiation Radiation with with Matter Matter

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Interaction of Interaction of Radiation Radiation with with Matter Matter

Interaction with electrons

Light scattering

Interaction with electrons

X-ray scattering

Scattering ‘strength’ is proportional to Z Interaction with electron spin possible Interaction with nuclei (protons and neutrons)

Neutron scattering

Scattering ‘strength’ does not vary systematically Interaction with nuclear spin possible Interaction with electrons and electron spin possible

Atomic Scattering factors / length

H

R.Winter, F. Noll: Methoden der biophysikalischen Chemie, Teubner (1998)

X-Rays Neutrons atomic mass / g mol-1

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Comparison Comparison Neutron Neutron-

  • and

and X X-

  • ray

ray-

  • scattering

scattering length length

some some relevant relevant elements elements [10 [10-

  • 12

12 cm]

cm] n X-ray

1H

  • 0.37

0.28

2H

0.67 0.28

12C

0.66 1.68

14N

0.94 1.96

16O

0.58 2.24

31P

0.51 4.2

32S

0.28 4.48

56Fe

0.95 6.72

Neutron Neutron Scattering Scattering Length Length

  • f
  • f biological

biological relevant relevant elements elements [10 [10-

  • 12

12 cm]

cm]

[F. Sears (1986), H. Glättli und M. Goldmann (1987)]

deuterate whenever possible!

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Contrast Contrast Variation Variation

When the monster came, Lola, like the peppered moth and the arctic hare, remained motionless and undetected. Harold of course, was immediately devoured.

The The Concept Concept of

  • f Contrast

Contrast Variation Variation

Contrast = Difference of Scattering Length Densities

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Contrast = Difference of Scattering Length Densities p(R) = Particle(R) - LM(R) p(R) = Particle(R) - LM (R) =

Scattering Length Densitiy = Sum of Scattering Length of all Atoms in a Volume

X-Ray Scattering Neutron Scattering Volume Fraction D2O Scattering Length Density of the Solvent [1010 cm/cm3] Scattering Length Density of the Solute [1010 cm-2] Water Sugar

Synaptic Arrangement of the Neuroligin/b-Neurexin Complex Revealed by X-Ray and Neutron Scattering. D. Comoletti et al. Structure 15 (2007) 693–705

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Synaptic Arrangement of the Neuroligin/b-Neurexin Complex Revealed by X- Ray and Neutron

  • Scattering. D. Comoletti et al.

Structure 15 (2007) 693–705

Synaptic Arrangement of the Neuroligin/b-Neurexin Complex Revealed by X-Ray and Neutron Scattering. D. Comoletti et al. Structure 15 (2007) 693–705

Impossible to crystallize

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Synaptic Arrangement of the Neuroligin/b-Neurexin Complex Revealed by X-Ray andNeutron Scattering. D. Comoletti et al. Structure 15 (2007) 693–705

Deuterated!

Synaptic Arrangement of the Neuroligin/b-Neurexin Complex Revealed by X-Ray andNeutron Scattering. D. Comoletti et al. Structure 15 (2007) 693–705

Deuterated!

42% D2O

We „see“ the deuterated with neutrons and the whole complex with X-rays

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Synaptic Arrangement of the Neuroligin/b-Neurexin Complex Revealed by X-Ray andNeutron Scattering. D. Comoletti et al. Structure 15 (2007) 693–705

Distance Distribution

Setup of a SANS Instrument Setup of a SANS Instrument

GKSS

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A A Typical Typical SANS Instrument SANS Instrument Monochromator Crystal Selector

29 cm 25 cm

Number of plates: 72 thickness [mm]: 0.4 twist angle: 48.27° material: carbon fiber in epoxy with 10B or Gd

Monochromators Monochromators: Time of : Time of Flight Flight

t=0 t=x Chopper REFSANS@FRM-II

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A A Typical Typical SANS Instrument SANS Instrument Collimation Line A A Typical Typical SANS Instrument SANS Instrument Collimation Line Neutron Neutron guides guides

based on total reflection kC  2  b  = atoms / cm3 b = scattering length critical angle: sin c =  /  b/  Materials c [mrad] c [°] dc [nm] Al 0.81 0.048 62 Ni 1.70 0.10 29

58Ni

2.03 0.12 25 Fe 1.62 0.095 31 Co 0.86 0.051 58 glass 1.06 0.062

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A A Typical Typical SANS Instrument SANS Instrument Collimation Line Sample Position Detektor

Materials c [mrad] c [°] dc [nm] Al 0.81 0.048 62 Ni 1.70 0.10 29

58Ni

2.03 0.12 25 Fe 1.62 0.095 31 Co 0.86 0.051 58 glass 1.06 0.062

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Measurements Raw Data [Chaperonin GroEL] Data Integration Principle

Beam center Pixel size

'Mask' measurements

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Data Integration Correction: cos3()

Solid angle correction

Integration

Q [Å-1] Itot / monitor

'pure'

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Measurements Detector response: H2O Measurements

Detector response Water (H2O) 1mm Vanadium Plastic Strong incoherent scatterer Normalization Water (H2O) 1mm Vanadium Knowledge about the coherent cross section

I(q)norm = I(q) / T I(q)H2O / T H2O for all detector pixels

G.D. Wignall, F.S. Bates: Absolute calibration of small angle neutron scattering data. J. Appl. Cryst. (1987) 20, 28-40

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Integration

Q [Å-1] Normalized Itot / monitor

'divided by water'

SANS-1@FRG-1

10 m 10 m

SANS-2@FRG-1: 2 x 20 m D11@ILL: 2 x 40 m Rule of thumb: collimation length = sample-detector distance

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SANS-1@FRG-1

10 m 10 m

Neutron guide Collimator

Integration

Q [Å-1]

'with collimation correction'

Normalized Itot / monitor

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Considerations about Scattering data

Beam profile Wave length profile Sample concentration, dark current, backgroud subtraction (cuvette), dead time corrections Detektor resolution

Smearing Effects

solid angle correction

We considered so far:

detector response (division by water) flux reduction by collimation

We still have to consider:

Influences on the measured intensity: Smearing

Detektor resolution

Gauss-distribution WD I(q) = I(q) WD dq

m

Influence on medium and large q-range

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Finite collimation

Influences on the measured intensity: Smearing

Detektor resolution

I(q) = I(q) WD WC dq

m

Gauss-distribution WC Influence on small q-range

Finite collimation

Influences on the measured intensity: Smearing

Detektor resolution Wavelength resolution

I(q) = I(q) WD WC W dq

m

Gauss-distribution W Influence on medium and large q-range

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Influences on the measured intensity: Smearing

http://www.neutron.anl.gov/ Neutron Scattering Home Page http://pathfinder.neutron-eu.net/idb The Neutron Pathfinder http://ess-scandinavia.eu/about-esss ESS Scandinavia http://www.ill.fr/ ILL home http://www.isis.stfc.ac.uk/ ISIS http://sni-portal.uni-kiel.de/kfn/ Komitee Forschung mit Neutronen

Argonne National Lab

Thank your for your Attention!