X-ray and Neutron Radiography and

Tomography at NECSA

Presented by Gawie NothnagelNecsa-Wits Workshop; 10-11 September 2105

Frikkie de Beer, Mabuti Radebe, Robert Nshimirimana

Kobus Hoffman, Lunga Bam

Senior ManagerRadiation Science Department

4. Selective applications

2. Principle of radiography and tomography

5. Discussions

Outline

1. Introduction

4. Importance of users and collaboration

3. Facilities/instrumentation

The start of non-destructive imaging

“Horrified at the result, Bertha Roentgen saw in the image a premonition of death.”

Principle of Radiography

4

xρμexpII 0

axρμIIln 0

Mass attenuation coefficient

5

X-ray and neutron attenuation properties

SourceCollimator

DetectorObject

xeII 0

Beer-Lamberd Law of radiation attenuation:

I : the transmission radiation beamI0

: the incoming radiation beamΣ : macroscopic cross-section (cm-1)x : thickness of the sample (cm)

This why Necsa have both X-ray and neutron radiography

Water distribution in H-fuel cells

PSI

1.Principles of tomography

Cylindrical symmetry

22 yr

drrdx

dr

yr

rrgyf

22

r yr

dy

dy

dfrg

22

1

yf

Yes, measure many f(y) values, then determine g(r)

Can we construct the density distribution g(r) from the line integrals f(y)?

Abel inverse

dxrgf(y) L

General geometry

f(p, )

0L

IIlndlθr,gφp,f

Q

p

Radon’s method (1917)

10

dpfpf 2

02

1 ,

f(p, )Q

0

1

p

fdQg

p

dp

dp

fd

0

1

If repeated for many p values the integral can be computed

r yr

dy

dy

dfrg

22

1

Repeat for many Q values

Not a practical method, very noise sensitive

Nobel Prize: CAT

Fourier expansionFiltered back projectionIterative reconstruction

Reconstruction

12

2D 3D

1.Selected Applications

Water distribution in concrete

NoticeAggregateDistribution

Water

NUCLEAR WASTE RESEARCH

BUILDING MATERIALS

OIL & MINERALS EXPLORATION

ARCHEOLOGY & PALEOANTHROPOLOGY

(HERITAGE STUDIES)

Virtual extraction of a fossil from its host rock

No preparation

No damage or deconsolidation

Probing the remote past

Cynodont

Thermoregulation ?

Secondary Palate ?

200 million years

Travelling on a neutron beam

Osiris statuette

Egypt

Hypothesis: Symbolic markings

Archeology with neutronsArchaeology: Iron Stones from Wonderwerk Cave

Jacobson, L., et al., Archeometry 55, 1 (2013) 1- 13.

Neutrons tell a different story

Geology: Plaglioclase

Red (ortho) and green (clino) pyroxenes

Drill Core of oil bearing rock

Green pores: emptyRed pores: oil filledCan quantify pore interconnectedness

Water uptake in cement

Can extract quantitative data of comparable quality to weighing

But get spatial information

1.Our Facilities

MIXRAD @ Necsa

MICRO-FOCUS X-RAY TOMOGRAPHY FACILITY- NRF Sponsored- 1 July 2011

Beam line 2 : Neutron Radiography

SAFARI-1 reactor wall

Shielding

Beam stop / door

SAFARI-1 NEUTRON BEAMS LINES

NDIFF NRAD SANS

Hosted by: Necsa ; Wits; SU

Workshop: imaging with radiation

RESEARCH NEEDS

• Radiography / tomography in a real time application mode:– Conveyer belt : Evaluation of fruit (infestation)

• NEED: Fast computing

Thank You