Neutron activation of materials relevant for GERDA

Institut für Kern- und Teilchenphysik

March 12th 2009

GERDA-meeting - Padova

Alexander Domula

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① Neutron Introduction/Activation Experiments

② Neutron-Activations with 14MeV Neutrons

③ Activation of copper and stainless steel components

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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

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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

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Neutron Activation Experiments

'* n n XX AZ

AZ

inelastic scattering

74Ge(n,n‘)74Ge*

Neutron capture

74Ge(n,)75mGe

XX AZ

AZ

1 n

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Neutron Activation Experiments

xBA n

fast Neutron activation

63Cu(n,)60Co

76Ge(n,p)76Ga

59Co(n,p)59Fe

65Cu(n,2n)64Cu

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Neutron Activation Experiments

competing reaction channels• one product of different isotopes• one product of different reaction channels

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Neutron Activation Experiments

• spectroscopy of Neutron fields

• dosimetry

• measurement of Neutron-reaction cross-sections

• exploring nuclear level schemes

• material analysis

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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

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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

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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

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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

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Activation of stainless steel components• two ways to get 54Mn

56Fe(n,2np)54Mn 54Fe(n,p)54Mn not mentioned

14 MeV Neutrons!

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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

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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

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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)

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

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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

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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

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cobalt in copper ?

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Cross sections 59Co(n,x)• 59Co(n,2n)58Co only when 59Co(n,)56Mn is

visible

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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

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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 ?