Institut für Kern- und Teilchenphysik
Neutron activation of materials
relevant for GERDA
GERDA-meeting - Padova
Alexander Domula
March 12th 2009

Neutron Introduction/Activation
Experiments

Neutron-Activations with 14MeV
Neutrons

Activation of copper and stainless
steel components
2
Neutron Activation Experiments
Neutron sources:
• radioactive sources
- radioactive a-sources (210Po, 241Am,…)
- 7Li(a,n)10B, 9Be(a,n)12C, 13C(a,n)16O,…
- 241Am-9Be source Enmidd = 4,46 MeV
• nuclear fission
- Maxwell- or Wattspectra; E(jEmax) ≈ 1 MeV
3
Neutron Activation Experiments
• accelerators
- charged particle reactions
 7Li(p,n)10B (Q=-1,646 MeV)
 2H(d,n)3He (Q=3,266 MeV)
 3H(d,n)4He (Q=17,586 MeV;
En≈14,064 MeV)
- Bremsstrahlung  (g,n)-reactions
• cosmic ray reactions
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Neutron Activation Experiments
inelastic scattering
A
Z
X  n  ZAX *  n '

74Ge(n,n‘)74Ge*
Neutron capture
A
Z
X n

X g
A1
Z
74Ge(n,
g)75mGe
5
Neutron Activation Experiments
fast Neutron activation
A n  B  x
 59Co(n,p)59Fe
 65Cu(n,2n)64Cu
 63Cu(n,a)60Co
 76Ge(n,p)76Ga
6
Neutron Activation Experiments
competing reaction channels
• one product of different isotopes
• one product of different reaction channels
7
Neutron Activation Experiments
• spectroscopy of Neutron fields
• dosimetry
• measurement of Neutron-reaction
cross-sections
• exploring nuclear level schemes
• material analysis
8
Activation Experiments at 14 MeV
TUD Neutron Generator
motivation:
• GERDA meeting at Nov 2008
„Cosmogenic Radionuclides in stainless steel
and copper“
1. stainless steel
2. copper
G.Heusser, M. Laubenstein
9
10
Activation Experiments at 14 MeV
TUD Neutron Generator
• chemical composition of 1.4571 stainless
steel (X6CrNiMoTi17-12-2)
Element
Max.
fraction %
C
Si
Mn
P
S
Cr
Mo
Ni
Ti
0,08
1,00
2,00
0,045
0,015
18,5
2,5
13,5
0,7
+ rest consists of Fe
• activation experiments at neutron facility at
FZD Rossendorf
- stainless steel components (1.4571):
 Fe, Mo, Ni, Ti activated elementwise
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Activation of stainless steel
components (Fe)
• end irradiation Feb 12th 2009, 16:00
• short living nuclides
- Feb 12th 2009, 17:33:15, tL = 580 s
E [keV]
Nuclid
846,8
56-Mn
1811,38
56-Mn
2114,04
56-Mn
2524,18
56-Mn
3371,28
56-Mn
12
Activation of stainless steel
components (Fe)
• long living nuclides
- Feb 27th 2009, 11:42:13
tL = 256‘979 s
E [keV]
Nuclid
121,38
57-Co
319,79
51-Cr
510,99
Annihilation
810,76
58-Co
834,9
54-Mn
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Activation of stainless steel
components 54
• two ways to get Mn
 56Fe(n,2np)54Mn
 54Fe(n,p)54Mn not mentioned
 14 MeV Neutrons!
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cross section vs. Neutron Flux

j E (40MeV)
 0,22 
j E (10MeV)
• activation 2,6 times higer for
56Fe(n,2np)54Mn reaction
 maxFe( n , 2 np)
nat

max
nat
Fe( n , p )

 12,1
54Fe(n,p)54Mn
also important
15
Activation of stainless steel
components (Mo)
• long living nuclides tL = 165‘840 s
E [keV]
Nuclid
140,02
99-Mo / 99m-Tc
180,5
99-Mo
235,49
95m-Nb
765,76
95-Nb
777,93
96-Nb
934,54
92-Nb
1199,89
96Nb
1204,88
91m-Nb
1477,38
93m-Mo
16
Activation of stainless steel
components (Ni)
• short living nuclides
tL = 1‘750 s
E [keV]
Nuclid
121,21
57-Co
136,88
57-Co
127,75
57-Ni
510,8
Annihilation
810,58
58-Co
847,15
56-Co ?
1377,84
57-Ni
1758,27
57-Ni
1920,5
57-Ni
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Activation of stainless steel
components (Ti)
• long living nuclides
tL = 170‘465 s
E [keV]
Nuclid
158,72
47-Sc
174,77
48-Sc
510,94
46-Sc
888,99
48-Sc
983,33
48-Sc
1037,35
46-Sc
1120,49
47-Sc
1212,82
48-Sc
1312,12
48-Sc
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Activation of Copper
• end irradiation Feb 12th 2009, 16:00
• short living nuclides
- Feb 12th 2009, 17:07:24, tL = 1‘239 s
E [keV]
Nuclid
366,14
65-Ni
510,86
Annihilation
1115,7
65-Ni
1346,18
64-Cu
1482,18
65-Ni
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Activation of Copper
• long living nuclides
- Mar 2nd 2009, 12:03:33
tL = 169‘995 s
E [keV]
Nuclid
121,02
57-Co
135,03
57-Co
510,76
Annihilation
608,50
214-Bi
809,73
58-Co
1171,96
60-Co
1331,05
60-Co
1460,30
40-K
1763,63
214-Bi
2504,83
S 60-Co
2613,64
208-Tl
20
cobalt in copper ?
21
Cross sections
•
59Co(n,2n)58Co
visible
59Co(n,x)
only when
59Co(n,a)56Mn
is
22
Activation of Cobalt
• short living nuclides
- tL = 265 s
E [keV]
Nuclid
510,92
Annihilation
810,72
58-Co
846,76
56-Mn
1099,28
59-Fe
1291,85
59-Fe
1811,31
56-Mn
2113,97
56-Mn
2524,09
56-Mn
3373,84
56-Mn
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Summary
• Neutron activation is a powerful tool to
investigate radioisotope production
• First samples of Fe, Ni, Mo, Ti, Cu and
Co have been activated with 14 MeV
Neutrons
•
54Fe(n,p)54Mn
reaction can‘t be
neglected for 54Mn production on iron
• Observed 57Co by copper activation
due to nickel within Cu
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Next steps
• activation of 1.4571 stainless steel
sample provided by G. Heusser
• work towards cross section
measurement
• activation of chrome ?
• Activation of Argon ?
• Activation of any other Material of
interest for GERDA ?
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