Transcript ACCELERATOR PRINCIPLES AND TECHNIQUES

FRANK LABORTORY OF NEUTRON
PHYSICS
ION BEAM ANALYSIS
1. Diale Boitshoko Phenyo (UWC)
2. Sefage Amanda (UZ)
3. Nkosi Steven (CSIR)
Republic of South Africa
Supervisor: A.P. Kobzev (JINR, Dubna)
JINR Summer Practice 2009
VAN DE GRAAFF ACCELERATOR EG-5
Main Characteristics
•Energy region 0.9-3.5 MeV
•Energy spread less than 500eV
•Beam intensity 10µA for He and
30µA for H.
Types of ions used
•4He+ and H+
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ACCELERATOR EG-5
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ANALYTICAL METHODS
• Rutherford Backscattering Spectrometry (RBS)
• Elastic Recoil Detection Analysis (ERDA)
• Particle Induced X-ray Emission (PIXE)
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PRINCIPLE OF RBS
KINEMATIC FACTOR
 m2


2
2
E
( M  M 1 sin )  M 1 cos 
 1  2

E0 
M 2  M1


1
2
Atomic mass of target. Z
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2
SCATTERING CROSS SECTION
1
Z1Z 2e 2 4[(M 2  M sin  ) 2  M 2 cos )]2
 R ( E , )  (
)
1
2
2
4
2
4E
M sin  ( M  M sin  ) 2
2
2
2
1
2
Z1 - Atomic number of incident particle
Z2 - atomic number of target
M1 – Atomic mass of incident particle
M2 – Atomic mass of target
Ѳ - Scattering angle
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2
2
1
PRINCIPLE OF RBS
Stopping cross section
E0, Z1, M1
+
x
θ1
θ2


1 dE
эВ  см 2
N dx

N-Number of particles in the layer
ΔX
dE
-Energy
dx
1
loss per unit length
θ
E1  K m2  ( E0  Ein )  Eout
E1, Z2, M2
Ω
Detector
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RBS EXPERIMENTAL RESULTS
Layer
Element
Conc.
(at.%)
1
Niobium
100
Titanium
Oxygen
79
21
Silicon
100
Intensity(arb.)
2
3
A = σΩ .Q . Nt
A – total number of detected particles
Q – total no. of inc. Particles
Nt – no. of target atoms per unit area
Channel number
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RBS EXPERIMENTAL RESULTS
Channel number
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Layer
Element
Thickness (nm)
1
Titanium
418
2
Niobium
254
3
Silicon
2 mm
RBS EXPERIMENTAL RESULTS
4000
Energy = 2.01 MeV, H
+
Detector 
3500
Yield Sc.
3000
Layer
Element
Conc.at%
1
Titanium
Carbon
Oxygen
Titanium
Silicon
Oxygen
Silicon
80
10
10
40
50
10
100
C
O
2
2500
Si
Ti
2000
3
1500
1000
Si-Substrate
500
0
200
400
600
800
1000
1200
Channel number
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Thickness
(nm)
180
42.3
2 mm
PRINCIPLE OF ELASTIC RECOIL
DETECTION ANALYSIS
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ERDA-RESULTS
experimental
simulated
4000
Detector  = 135
3000
2500
Carbon
Conc. (%)
H ydrogen
35
C arbon
35
Silicon
30
2000
1500
Silicon
1000
Thickness = 2600E+15 at./cm2
500
0
200
400
600
800
1000
1200
Channel number
Counts
BackScattering Intersity
3500
Energy = 2.297 MeV, 4He+
Element
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ERDA – RESULTS cont,d
Element
Conc. (%)
H ydrogen
26
C arbon
60
O xygen
14
Thickness = 1570E+15 at./cm2
Channel number
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Channel number
PRINCIPLE OF PIXE
Characteristics X-rays
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PRINCIPLE OF PIXE
Characteristics X-rays
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PRINCIPLE OF PIXE
Moseley law
•
•
•
•
•
Rc – Rydberg’s constant
Z – atomic number
Sn – screening constant
n – main quantum number
ν - frequency of X-ray
quantum
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CALIBRATION
90
80
13.94
17.75
70
Intensity
60
50
16.84
40
30
20.12
11.89
3.35
26.35
20
10
0
200
400
600
800
1000
Channel number
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1200
1400
1600
AEROSOL ANALYSIS BY PIXE & RBS
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AEROSOL ANALYSIS BY PIXE & RBS
4000
C
3500
N
Aerosol
Ep=2.005 MeV
Backscattering yield
3000
O
2500
=135
0
2000
F
Na Al
Si
1500
1000
S Ca Fe
500
0
550
600
650
700
Channel number
JINR Summer Practice 2009
750
800
AEROSOL ANALYSIS BY PIXE & RBS
Element
Concen. At. %
Method
Element
Concen. At. %
Method
C
41
RBS
K
0.1
PIXE
N
20.5
RBS
Ca
0.53
RBS
O
28
RBS
Mn
0.007
PIXE
F
2.6
RBS
Fe
0.14
RBS
Na
2.5
RBS
Cu
0.002
PIXE
Mg
1.3
RBS
Zn
0.01
PIXE
Al
1.3
RBS
As
0.001
PIXE
Si
1.8
PIXE
Sr
0.0006
PIXE
S
0.2
RBS
Zr
0.005
PIXE
Cl
0.01
PIXE
Ba
0.01
PIXE
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CONCLUSION
• Non-destructive methods ( Different fields i.e. Electronic devices , Multi layerstructures, geologist, archaelogist etc)
• Determine structure and composition of materials
• Elemental analysis
• Elemental concentration, depth profile in thin films ( < 1 at.%)
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CONCLUSION cont.d
ELEMENT
Ti
Nb
MINIMUM
THICKNESS, nm
30
10
MAXIMUM
THICKNESS, nm
1800
1500
264
169,5
REAL THICKNESS,
nm
SENSITIVITY, at/cm2
2x10xx16
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1x10xx16
Siyabonga
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