measurement of the 241 am(n,2n) reaction cross section using the activation method
DESCRIPTION
Measurement of the 241 Am(n,2n) reaction cross section using the activation method. G. Perdikakis 1,2 , C. T. Papadopoulos 1 , R. Vlastou 1 , A. Lagoyannis 2 , A. Spyrou 2 , M. Kokkoris 1 , S. Galanopoulos 1 , N. Patronis 1 , D. Karamanis 3 , Ch. Zarkadas 2 , G. Kalyva 2 , and S. Kossionides 2. - PowerPoint PPT PresentationTRANSCRIPT
Measurement of the 241Am(n,2n) reaction cross section using the activation method
G. Perdikakis1,2, C. T. Papadopoulos1, R. Vlastou1, A. Lagoyannis2, A. Spyrou2, M. Kokkoris1, S. Galanopoulos1, N. Patronis1, D. Karamanis3, Ch. Zarkadas2, G. Kalyva2,
and S. Kossionides2
1 Department of Physics, National Technical University of Athens, Athens, Greece
2Institute of Nuclear Physics, NCSR “Demokritos”, Athens, Greece
3 Department of Physics, University of Ioannina, Ioannina, Greece
n_TOF Collaboration
G. Perdikakis
•Motivation
•Experimental
•Analysis
•Results for 241Am(n,2n)
•Theoretical Calculations (in
progress)
•Other reactions studied – Future
Plans
Outline of the talk
G. Perdikakis
Transmutation of MAs - Important Reaction Channels
Neutron emission channels σ(n,xn)
Fission Channels σ(n,xnf)
Not enough experimental data !
Theoretical Predictions
Experimental Investigation of Theoretical Model Parametres required
G. Perdikakis
Existing Data
241Am: One of the most abundant isotopes in nuclear waste and one of the most radiotoxic elements
G. Perdikakis
241Am(n,2n)240Am
Energy Range of Interest:
8-12 MeV
G. Perdikakis
~ 105
n/cm2s
~ 106
n/cm2s
~ 105
n/cm2s
Monoenergetic Neutron Beams @ INP “Demokritos”
p+ or d+ beam
2H(d,n)3He
3H(d,n)4He
5.5MV Tandem VdG
5 – 12 MeV
16 – 20 MeV
7Li(p,n)7
Be150 – 650 keV
Shielding
wall
G. Perdikakis
The Activation Target
27 Al foil
3mm
Pb shield
37 GBq 241 Am target
Stainless Steel
n Beam
G. Perdikakis
Irradiation Setup
241Am Target
d+
D filled Gas Cell
BF3 Neutron Counter
n Beam
HPGe
Pb
9cm
ΔΕn: < 100 keV
Parafin
G. Perdikakis
2 m
242Am
2n+240Am
240Pu
n+241Am
n+241Am
3n+239Am
T1/2=50.8h
Outline of the Reaction 241Am(n,2n)240Am
n
γ
FissionE,J,π
5 days of irradiation
for each beam
energy !
987.8 keV (I=73%)
888.8 keV (I=25%)
Most Intense γ-rays:
G. Perdikakis
@ 10.6 MeV
HPGe spectrum
1014.7 keV 241Am
987.8 keV 240Am
984.5 keV 238Np +154Eu
955.7 keV 241Am
154Eu
ΦN
N=σ
τ
p 1
εFI
NtN
γ
γBp
'''γ
'γ
τ εFI
NN
εF
εF
N
I
I
N
N
N ''
'γ
'γ
γ
γ
τ
p
Reaction Cross
Section
G. Perdikakis
G. Perdikakis
Results
Results
G. Perdikakis et al. , Phys. Rev. C - In press
G. Perdikakis
242Am
2n+240Am
240Pu
n+241Am
n+241Am
3n+239Am
T1/2=50.8h
Outline of the Reaction 241Am(n,2n)240Am
n
γ
FissionE,J,π
Hauser Feshbach:
Preequilibrium contribution : Exciton Model
c c
ba
TTT
G. Perdikakis STAPRE/F
dπJ,ε,ρε+UU
ω
2πexp+=UΤ BA,
'BA,
BA,
'JπBA,
1
1
The double-humped fission barrier
Fission
n+X
Saddle A states
Saddle B states
Deformation, β
scission
βΝ
n
Normal states
βΑβΒ
UA UB
ħωΑ
ħωΒ
ρΑ ρΒρΝ
G. Perdikakis `
Main parametres of the calculation
Fission Barrier Parametre UA,UB,ħωΑ,ħωΒ
Level Density, ρ(U,J), at the saddles and at normal deformation
Deduced from experimental data
(V. M. Maslov. RIPL-1 Handbook. TEXDOC-000, IAEA, Vienna, 1998, Ch. 5.)
Transmission Coefficients
for neutrons,Τn
Coupled Channels OMP for actinides
(Ignatyuk et. al. Sov. J. Nucl. Phys. 51, (5), 1990)
G. Perdikakis
Generalized Superfluid Model of the nucleus
Shell, Superfluid pairing and Collective effects, important for the calculation
Ignatyuk et al, Sov. J. Nucl. Phys 29, (4), 1979
JfJ),(U')Κ(U'Κ)ρ(U'J),ρ(U' rotvibr
a=ã[1+δw·f(U-Econd)]
G. Perdikakis
Results 241Am(n,F)
Preliminary !!!
G. Perdikakis
241Am(n,2n)
• 232Th(n,2n) D. Karamanis et al. NIM A 505, 381, (2003)
• n-induced reactions on Ge, Hf and Ir isotopes In progress
• 237Np(n,2n) To be done
G. Perdikakis
Conclusions
Measurement of the 241Am(n,2n) reaction @ En = 8.8 – 11.4 MeV
Theoretical calculations in progress 241Am(n,2n)
241Am(n,F)
Other measurements
THE END
Results
241Am(n,2n)
Preliminary !!!
G. Perdikakis
Conclusions and Future Perspectives
Systematic Experimental Investigation of 241Am(n,2n) Reaction Cross Section,
for the first time
Consistent Theoretical Description of 241Am(n,2n) Reaction, in Reasonable
Agreement with Experimental Data.
Experimental Investigation to be Continued at Lower Energies
Improvement of Theoretical Description over the whole energy range
241Am(n,2n)240Am
Results
241Am(n,2n)240Am
241Am(n,f)
Energy Production and Nuclear Waste Transmutation in ADS Systems
Higher Fission/Captu
re ratio
More effective
Transmutation
S. Taczanowski et. al. Applied Energy 75, 97, (2003)
Sub-critical Systems
Transmutation of
Nuclear Waste
Neutrons produced
by Spallation Reaction
in Accelerator
Main Characteristics
Neutron Flux in Reactor Core affected by n-induced reactions
HPGe
Pb shielding
241Am Target
Off Line
Irradiation Setup
241Am Target
d+
D filled Gas Cell
BF3 Neutron Counter
n Beam
Parafin
0 100000 200000 300000 400000
0
1000000
2000000
3000000
4000000
5000000
Neu
tron
Flu
x(c
ou
nts
)
Irradiation Time (sec)
En= 10.6 MeV
Neutron Flux vs Time
5 days of Irradiation
Mapping the Neutron beam fluctuations
0 100000 200000 300000 400000
0
1000000
2000000
3000000
4000000
5000000
Neu
tron
Flu
x
(cou
nts
)
Irradiation Time (sec)
En = 10.6 MeV
Neutron Flux vs Time
5 days of Irradiation
HPGe
Pb
Experimental DifficultiesHighly radioactive target,
Relatively long half life of 240Am (50.8 h)
Measurement of the 241Am(n,2n) cross section by
the activation method