Xray and neutron radiography

1. X-ray and Neutron
Radiography and
Tomography at NECSA
Presented by Gawie Nothnagel
Necsa-Wits Workshop; 10-11 September 2105
Frikkie de Beer, Mabuti Radebe,
Robert Nshimirimana
Kobus Hoffman, Lunga Bam
Senior Manager
Radiation Science Department

2. 4. Selective applications
2. Principle of radiography and tomography
5. Discussions
Outline
1. Introduction
4. Importance of users and collaboration
3. Facilities/instrumentation

3. The start of non-destructive imaging
“Horrified at the result, Bertha Roentgen saw in the image a premonition of death.”

4. Principle of Radiography
4
 
x
ρ
μ
exp
I
I 0 

  a
x
ρ
μ
I
I
ln 0 

Mass attenuation coefficient

5. 5
X-ray and neutron attenuation properties
Source
Collimator
Detector
Object
x
e
I
I 

 0
Beer-Lamberd Law of
radiation attenuation:
I : the transmission radiation beam
I0
: the incoming radiation beam
Σ : macroscopic cross-section (cm-1)
x : thickness of the sample (cm)
This why
Necsa have
both X-ray
and neutron
radiography

6. Water distribution in H-fuel cells
PSI

7. 1.
Principles of tomography

8. Cylindrical symmetry
2
2
y
r
dr
r
dx


    dr
y
r
r
r
g
y
f
2
2



 

  




r y
r
dy
dy
df
r
g
2
2
1

 
y
f
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
 




 dx
r
g
f(y) L

9. General geometry
f(p, )
     
0
L
I
I
ln
dl
θ
r,
g
φ
p,
f 
 


Q
p

10. Radon’s method (1917)
10
    



d
p
f
p
f 

2
0
2
1
,
f(p, )
Q
  



0
1
p
f
d
Q
g 
p
dp
dp
f
d




0
1

If repeated for many p values the integral can be computed
  




r y
r
dy
dy
df
r
g
2
2
1

Repeat for many Q values
Not a practical method, very noise sensitive

11. Nobel Prize: CAT
Fourier expansion
Filtered back projection
Iterative reconstruction

12. Reconstruction
12
2D 3D

13. 1.
Selected Applications

14. Water distribution in concrete
Notice
Aggregate
Distribution
Water
NUCLEAR WASTE RESEARCH
BUILDING MATERIALS
OIL & MINERALS EXPLORATION
ARCHEOLOGY & PALEOANTHROPOLOGY
(HERITAGE STUDIES)

15. Virtual extraction of a fossil from its host rock
No preparation
No damage or
deconsolidation

16. Probing the remote past
Cynodont
Thermoregulation ?
Secondary Palate ?
200 million years

17. Travelling on a neutron beam
Osiris statuette
Egypt

18. Hypothesis: Symbolic markings
Archeology with neutrons
Archaeology: Iron Stones from Wonderwerk Cave
Jacobson, L., et al., Archeometry 55, 1 (2013) 1- 13.
Neutrons tell a different story

19. Geology: Plaglioclase
Red (ortho) and green (clino) pyroxenes

20. Drill Core of oil bearing rock
Green pores: empty
Red pores: oil filled
Can quantify pore interconnectedness

21. Water uptake in cement
Can extract quantitative
data of comparable
quality to weighing
But get spatial
information

22. 1.
Our Facilities

23. MIXRAD @ Necsa
MICRO-FOCUS X-RAY TOMOGRAPHY FACILITY
- NRF Sponsored
- 1 July 2011

24. Beam line 2 :
Neutron Radiography
SAFARI-1
reactor wall
Shielding
Beam stop /
door

25. SAFARI-1 NEUTRON BEAMS
LINES
NDIFF NRAD SANS

26. Hosted by: Necsa ; Wits; SU
Workshop: imaging with radiation

27. RESEARCH NEEDS
• Radiography / tomography in a real time application mode:
– Conveyer belt : Evaluation of fruit (infestation)
• NEED: Fast computing

28. Thank You