Date post: | 18-Dec-2015 |
Category: |
Documents |
Upload: | lilian-logan |
View: | 220 times |
Download: | 2 times |
Neutron activation of materials relevant for GERDA
Institut für Kern- und Teilchenphysik
March 12th 2009
GERDA-meeting - Padova
Alexander Domula
2
① Neutron Introduction/Activation Experiments
② Neutron-Activations with 14MeV Neutrons
③ Activation of copper and stainless steel components
3
Neutron Activation Experiments
Neutron sources:
• radioactive sources- radioactive -sources (210Po, 241Am,…)- 7Li(,n)10B, 9Be(,n)12C, 13C(,n)16O,…- 241Am-9Be source En
midd = 4,46 MeV
• nuclear fission- Maxwell- or Wattspectra; E(
max) ≈ 1 MeV
4
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 (,n)-reactions
• cosmic ray reactions
5
Neutron Activation Experiments
'* n n XX AZ
AZ
inelastic scattering
74Ge(n,n‘)74Ge*
Neutron capture
74Ge(n,)75mGe
XX AZ
AZ
1 n
6
Neutron Activation Experiments
xBA n
fast Neutron activation
63Cu(n,)60Co
76Ge(n,p)76Ga
59Co(n,p)59Fe
65Cu(n,2n)64Cu
7
Neutron Activation Experiments
competing reaction channels• one product of different isotopes• one product of different reaction channels
8
Neutron Activation Experiments
• spectroscopy of Neutron fields
• dosimetry
• measurement of Neutron-reaction cross-sections
• exploring nuclear level schemes
• material analysis
9
Activation Experiments at 14 MeVTUD Neutron Generator
motivation:
• GERDA meeting at Nov 2008
„Cosmogenic Radionuclides in stainless steel and copper“
G.Heusser, M. Laubenstein1. stainless steel2. copper
10
11
Activation Experiments at 14 MeVTUD Neutron Generator
• chemical composition of 1.4571 stainless steel (X6CrNiMoTi17-12-2)
Element C Si Mn P S Cr MoMo NiNi TiTi
Max. fraction %
0,08 1,00 2,000,04
50,01
5 18,5 2,52,5 13,513,5 0,70,7
++ rest consists of FeFe
• activation experiments at neutron facility at FZD Rossendorf- stainless steel components (1.4571):
Fe, Mo, Ni, Ti activated elementwise
12
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
13
Activation of stainless steel components (Fe)• long living nuclides
- Feb 27th 2009, 11:42:13tL = 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
14
Activation of stainless steel components• two ways to get 54Mn
56Fe(n,2np)54Mn 54Fe(n,p)54Mn not mentioned
14 MeV Neutrons!
15
cross section vs. Neutron Flux
1,12max
),(
max
)2,( pnFe
npnFe
nat
nat
22,0)MeV10(
)MeV40(
E
E
• activation 2,6 times higer for 56Fe(n,2np)54Mn reaction
54Fe(n,p)54Mn also important
16
Activation of stainless steel components (Mo)
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
• long living nuclides tL = 165‘840 s
17
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
18
Activation of stainless steel components (Ti)
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
• long living nuclides tL = 170‘465 s
19
Activation of Copper
E [keV] Nuclid
366,14 65-Ni
510,86 Annihilation
1115,7 65-Ni
1346,18 64-Cu
1482,18 65-Ni
• end irradiation Feb 12th 2009, 16:00• short living nuclides
- Feb 12th 2009, 17:07:24, tL = 1‘239 s
20
Activation of Copper• long living nuclides
- Mar 2nd 2009, 12:03:33tL = 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 60-Co
2613,64 208-Tl
21
cobalt in copper ?
22
Cross sections 59Co(n,x)• 59Co(n,2n)58Co only when 59Co(n,)56Mn is
visible
23
Activation of Cobalt• short living nuclides
- tL = 265 sE [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
24
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
25
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 ?