x-ray and neutron radiography and tomography at necsa presented by gawie nothnagel necsa-wits...
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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.”
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
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
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
Water distribution in concrete
NoticeAggregateDistribution
Water
NUCLEAR WASTE RESEARCH
BUILDING MATERIALS
OIL & MINERALS EXPLORATION
ARCHEOLOGY & PALEOANTHROPOLOGY
(HERITAGE STUDIES)
Probing the remote past
Cynodont
Thermoregulation ?
Secondary Palate ?
200 million years
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
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
RESEARCH NEEDS
• Radiography / tomography in a real time application mode:– Conveyer belt : Evaluation of fruit (infestation)
• NEED: Fast computing