Post on 17-Jan-2016
CENTRO ATOMICO BARILOCHE - ARGENTINA
MODELING AND MEASUREMENTS OF
NEUTRONIC PROPERTIES OF NEW CRYOGENIC
NEUTRON MODERATORS
CENTRO ATOMICO BARILOCHE - ARGENTINA
J.R. Granada, F. Cantargi, S. Petriw, J. DawidowskiCentro Atómico Bariloche
Comisión Nacional de Energía Atómica & CONICET
ARGENTINA
CENTRO ATOMICO BARILOCHE - ARGENTINA
NyR - SOME RESEARCH ACTIVITIES
Total Cross Section Measurement and Calculation (subthermal to epithermal range) [+T]
Neutron Diffraction [+T]
Deep Inelastic Neutron Scattering [+T]
Non Destructive Hydrogen Content Determination
Scattering Kernels for Hydrogeneous Materials
CENTRO ATOMICO BARILOCHE - ARGENTINA
Scattering Kernels for Hydrogeneous Materials
Previous Related Experience:
THE SYNTHETIC SCATTERING FUNCTION
[J.R. Granada, Phys.Rev. B 31, 4167 (1985)]
0 20 40 60 80 100 120 1400
2
4
6
8
10
12
14
16
Multiple
Single
H2O
Cro
ss S
ectio
n (b
arn/
ster
ad)
Angle (degrees)
ANGULAR DISTRIBUTIONSExperiment performed at the Orphee reactor (λ=0.7045 Ả)
TOTAL CROSS SECTIONSLight water and plexiglass
at room temperature
1E-3 0.01 0.1 1 10
20
30
40
50
60708090
100
200
300
(%10)
PMMA
H2O
Tot
al C
ross
Sec
tion
(bar
n)
Energy (eV)
0.00 0.02 0.04 0.06 0.08 0.100.0
5.0x103
1.0x104
1.5x104
2.0x104
D2O
SSF M.G. Silk J.W. Daughtry H.J. Jones F.R. Westfall N.G. Sjöstrand
Dec
ay C
onst
ant (
s-1)
Buckling (cm-2)
DIFFUSION PARAMETERSPulse decay time for a
traditional “Hokkaido configuration”
DIFFUSION PARAMETERSDecay constant of heavy water
at room temperature
0 2 4 6 8 100
50
100
150
200
250
300
TD = 124.8 s
Kiyanagi et al., NIM A312, 561 (1992)
(12x12x5)
H2 Decoupled
CH4 Decoupled
H2 Coupled
Dec
ay T
ime
(se
c)
Wavelength (Å)
J.Nucl.Mat. 139, 158 (1986)
Multiple scattering corrections to the observed spectra
(MARI experiment)
Phys.Rev. B 58, 706 (1998)
CENTRO ATOMICO BARILOCHE - ARGENTINA
1E-3 0.01 0.1 120
40
60
80
100
120
140160180200
CH4
GRANADA - CAB Nov. '94
Melkonian (293K) Rogalska (105K) SM (105K) NJOY (100k) SM (293K)
Cro
ss S
ect
ion
(b
arn
)
Energy (eV)
1020
3040
1020
3040
50
1
10
100
1020
3040
1020
3040
50
1
10
100
NJOY/ENDF/B-VI.2NJOY/Synthetic Model
Inci
dent
Inci
dent
Final
Solid Methane - 20K
Final
SYNTHETIC SCATTERING KERNELSPhys.Rev. B 31, 4167 (1985)
CENTRO ATOMICO BARILOCHE - ARGENTINA
1E-4 1E-3 0.01 0.1 1
100
150
200
250
300
350
(*) Grieger et al., J.Chem.Phys. 109,3161 (1998)
SOLID METHANE(ca 20K)
Exper.(*) NJOY NyR
4H-C
ross
Sec
tion
(b)
Energy (eV)
CENTRO ATOMICO BARILOCHE - ARGENTINA
Cross sections calculated through ‘synthetic model’ compared with exp. data at different temperatures
Cryogenic Moderators
10-5 10-4 10-3 10-2 10-1 1000.1
1
10
100
p-H2
n-H2
SSF ENDF/B-VI Expt.
Tot
al C
ross
Sec
tion
(bar
n)
Energy (eV)
CENTRO ATOMICO BARILOCHE - ARGENTINA
Development of New Cold Neutron Moderators
(Main objective of the ACoM collaboration)
SCATTERING KERNELS FOR ADVANCEDMODERATOR MATERIALS
CENTRO ATOMICO BARILOCHE - ARGENTINA
NJOY Calculations
Synthetic Frequency Spectrum
Combination of experimental and synthetic contributions
Continuous part associated to traslational and rotational motions of the molecular system
Vibrational modes (discretes)
NJOY
•(library ENDF)• scattering•mass•Scattering proc• SFS
Gaussian approx.
100 phonons
S(Q)[SFS]
LEAPR
S(Q)[SFS]
(E)kernels[SFS]
integrals libraryACE[SFS]
THERMR ACER
Solid Methane: applications of the SFS concept
0.0001 0.001 0.01 0.1 1
100
1000
10000
100000
Espectro de neutrones(MCNP)Metano Sólido a 22K
[E
]
E [eV]
HB SFS (biblio MCNP)
Solid Methane: using SFS
Neutron spectra at different temps calculated with MCNP Neutron spectra at different temps calculated with MCNP using SFS´based libraries.using SFS´based libraries.
0.001 0.01 0.1 1
100
1000
10000
100000
Espectro de neutrones (MCNP)Metano sólidoBibliotecas a partir del SFS
[E
]
E [eV]
22K 30K 50K 77K
Light Water Ice
Cross Sections obtained from SFS
1x10-4 1x10-3 1x10-2 1x10-1 1x100
0.1
1
10
Inelástica
Hielo
Se
cció
n E
fica
z [b
arn
s]
E [eV]
115K 77K 50K 30K 20K
10-2 10-1 100
20
30
40
50
60
70
80
90
100
Hielo
Se
cció
n E
fica
z [b
arn
s]
E [eV]
Experimental 115K Total SFS 115K
Clathrate
Neutron X-sections and spectra calculated with the use of a Synth. Frequency Spectrum
1x10-4 1x10-3 1x10-2 1x10-1 1x100
2.5
25
Clatrato (SFS)
Se
cció
n E
fica
z [b
arn
s]
E [eV]
Inelástica 20K Inelástica 30K Inelástica 50K Inelástica 77K
10-3 10-2 10-1
100
1000
10000
Espectro de neutrones (MCNP)Clatrato (SFS)
[E
]
E [eV]
20K 30K 50K 77K
Clathrate
10-3 10-2 10-1 100
1000
10000
100000
Espectro de neutrones (MCNP)20K
[E
]
E [eV]
Clatrato Hielo Metano
Clathrate, Methane and Ice at 20K
Cross sections calculated through ‘synthetic model’ compared with exp. data at different temperatures
Cryogenic Moderators
Neutron spectra from moderator substances at different temperatures (calculated)
Cryogenic Moderators
10-4 10-3 10-2 10-1 100 101
Neu
tron
flu
x [a
.u.]
E [eV]
Methane 22K Para-hydrogen 20 K Mesitylene 20 K
Calculated spectra of typical cryogenic moderators for the “Hokkaido Configuration”
CENTRO ATOMICO BARILOCHE - ARGENTINA
SCATTERING KERNELS FOR ADVANCEDMODERATOR MATERIALS
Latest Development of New Cold Neutron Moderators
CENTRO ATOMICO BARILOCHE - ARGENTINA
Neutron Scattering Kernel for Solid Methane in phase II
Rolando Granada
Centro Atomico Bariloche
ARGENTINA
CENTRO ATOMICO BARILOCHE - ARGENTINA
CENTRO ATOMICO BARILOCHE - ARGENTINA
The scattering law of a molecular system
R lν(t) denotes the position of the atom v within the molecule l , can be written as the sum of inter (l l´)- and intra (l l´)- molecular contributions (also referred to as the outer and inner terms, respectively).
The intermediate scattering function is
tiiaa
tiiaat
lvlvl
lvlvvv
vllvll
vllvvv
´´*
´,
´´´
´´*
´,
.exp0.exp
.exp0.exp,
RQRQ
RQRQQ
tiiaaedtS vllvll
vllvvv
ti´´
´,´´
*
´,
.exp0.exp2
1, RQRQQ
CENTRO ATOMICO BARILOCHE - ARGENTINA
'
22
222intra
1
.3
,
HHHHH
iHc
HHHi
HcCC
Cc
fSS
bb
fbbgfbt
SS
Q
Carbon self Hydrogen self
Interference caused by Proton spin correlations
gГ = 1 for disordered molecules
= 3 for ordered molecules
CENTRO ATOMICO BARILOCHE - ARGENTINA
1E-4 1E-3 0.01 0.1 1
100
200
300
400
To
tal C
ros
s S
ec
tio
n (
ba
rn)
E (eV)
Elast.self Elast. all Inelast. Total
4K
Calculated components of σT(E) for CH4 II at 4KCH4 II
CENTRO ATOMICO BARILOCHE - ARGENTINA
1E-4 1E-3 0.01
200
400
600
800
To
tal C
ros
s S
ec
tio
n (
ba
rn)
E (eV)
0.3K
10K
Comparison of calculated σT(E) with experimental data of Grieger et al.
J.Chem.Phys.109,3161 (1998)
CH4 II
CENTRO ATOMICO BARILOCHE - ARGENTINA
0.1 1 10
300
400
500
600
To
tal C
ros
s S
ec
tio
n (
ba
rn)
T (K)
1.5 meV
0.9 meV 0.1 meV
Temperature dependence of σT at low energies caused by spin correlations
Open circles: this workClosed circl.: Grieger exper.Lines: Ozaki calculations
CH4 II
CENTRO ATOMICO BARILOCHE - ARGENTINA
1E-3 0.01 0.1 1
1E-6
1E-5
1E-4
Ne
utr
on
Flu
x (
au
)
E (eV)
Meth 22K Meth 4K
CENTRO ATOMICO BARILOCHE - ARGENTINA
Neutron Cross Section Libraries for Aromatic Systems of interest as Cold Neutron Moderators
F. Cantargi, J.R. Granada, L.A. Rodríguez Palomino,S. Petriw, M.M. Sbaffoni
Centro Atomico Bariloche
ARGENTINA
CENTRO ATOMICO BARILOCHE - ARGENTINA
• Good moderator for a cold neutron source good resistance to radiation (S.Kulikov, E. Shabalin, V. Melikhov, E. Kulagin, Proceedings of the ICANS-XVI Meeting, Neuss, Germany, 2003)
high protonic density low-energy excitations (I. Natkaniec, Proceedings of the ACoM6 Meeting, ESS-FZ Julich, 2002)
easy handling
MESITYLENE
CENTRO ATOMICO BARILOCHE - ARGENTINA
0.00 0.02 0.04 0.06 0.08 0.100
2
4
6
8
10
12
Z(E
) (a
u))
E (eV)
Phase I Phase II Phase III
MESITYLENE
Low energy part of ouradopted SFS
CENTRO ATOMICO BARILOCHE - ARGENTINA
1E-3 0.01 0.1 1200
400
600
800
1000
1200
To
tal
Cro
ss
Se
cti
on
(b
arn
s)
E (eV)
Experim. Calcul.
MESITYLENE32K
(Phase III)
Experiments using the Bariloche LINAC
CENTRO ATOMICO BARILOCHE - ARGENTINA
1E-3 0.01 0.1 1200
400
600
800
1000
To
tal
Cro
ss
Se
cti
on
(b
arn
s)
E (eV)
Experim. Calcul.
MESI (3:2) TOL32 K
Experiments using the Bariloche LINAC
CENTRO ATOMICO BARILOCHE - ARGENTINA
1E-3 0.01 0.11E-6
1E-5
Ne
utr
on
Flu
x
E (eV)
Benzene Toluene Mesityl ph II Mesityl ph III Mesi (3:2) Tol
20 K
Calculated Spectra for the Methyl derivatives of Benzene
CENTRO ATOMICO BARILOCHE - ARGENTINA
1E-3 0.01 0.1 11E-7
1E-6
1E-5
1E-4
Neu
tro
n F
lux
E (eV)
Methane ph I Clathrate Mesitylene ph II Mesi (3:2) Tol Para hydrogen
20 K
Comparison of Mesitylene and Mixture with standard moderators
CENTRO ATOMICO BARILOCHE - ARGENTINA
Thank you!
CENTRO ATOMICO BARILOCHE - ARGENTINA
25 MeV e-LINAC
LINAC
Bunker Experimental room
Scattering Experiments
Detector bank
Sample changer
P b n
n
e-
WATER
25 MeV e-LINAC
73 cm total height; 50 cm diameter; 38 cm moderator height. Stainless steel. Zircaloy-4 windows
Cryogenic Moderators
Cryo-Moderator contained in succession of zircalloy-4 containers
Cryogenic Moderators
19,6cm20,2cm
5 cm
CENTRO ATOMICO BARILOCHE - ARGENTINA
CENTRO ATOMICO BARILOCHE - ARGENTINA