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Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx 1
Joint Research Centre (JRC)IRMM - Institute for Reference Materials and Measurements
Geel - Belgiumhttp://irmm.jrc.ec.europa.eu/
http://www.jrc.ec.europa.eu/
Neutron Induced
Cross Section Measurements
Workshop on Nuclear Reaction Data for Advanced Reactor Technologies
Trieste, Italy, 19 – 30 May 2008
2Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx
Importance of neutron induced reactions for reactor operation
• Nuclear fuelU, Pu, Th (n,f), (n,), …
• Fission products (“neutron poisoning”)103Rh, 135Xe, 135Cs, 149Sm (n,)
• Structural materialsFe, Cr, Ni
n,xn
n,3n
n,3n
233Th
232Th
231Th
230Th 230Pa
231Pa
232Pa
233Pa
234Pa 234U
233U
232U
n,f
n,2n n,e.g. Th-U cycle
Safety + Economics
3Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx
Cross section data
Integral data
Theory EvaluationEvaluatedData File
Industry
Microscopicdata
Research Laboratories
RegulatoryBodies
Benchmark measurements
4Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx
Neutron induced reactions
• Neutron induced reactionsn + X Y + r
• Various reaction channelsn + X X + n (n,n) elastic scattering n
Y + (n,) capture Y1 + Y2 (n, f) fission f
Y + p (n,p) p
...
• Probability for a reaction (n,r) to occur:Partial cross section: r
• Total cross sectiontot = r = n + + f + p + …
5Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx
Cross section
• A cross section has the dimension of an area.
• The unit of a cross section is taken as: 1 barn, 1 b = 10-24 cm2.
• Reaction rate for a neutron beam on a target (thin layer) :
n : neutron flux
NA : Avogadro constant
NX : number of nuclei
MX : molar mass of nucleus X
m(X) : mass of X
in most cases the number of nuclei per unit area are required (these will be denoted by n)
10-2 100 102 104 10610-4
10-2
100
102
104
59Co(n,)
(n)
/ bar
n
Neutron Energy / eV
)X(mM
NN
X
AX nXNR
6Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx
Resonance structure
A cross section as a function of En
shows a resonant structure, which can be described by a Breit-Wigner shape :
with
natural line width (FWHM)
ER resonance energy
22Rn
tot)2(EE
1~
133 134 135
0
4000
8000
t
R
ER
t /
bar
n
Neutron Energy / eV
o tot
tot /
ba
rn
7Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx
Cross sections : energy dependent
238U(n,tot) = 238U(n,n) + 238U(n,) tot = n +
• Resonance Region : D >
Resolved Resonance Region : R < D
Unresolved Resonance Region : R > D
• High Energy Region : D < 10-2 100 102 104 10610-2
102
106
88 90 92 940
5
10
15
Eo
D
Cro
ss-s
ectio
n / b
arn
Energy / eV
t
n
tot
ER
8Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx
Parameterisation of neutron cross sections by nuclear reaction theory
• Ensures consistency between partial and total cross sections
• Ensures consistency between cross section data in different energy regions
• Prevents the use and recommendation of unphysical data
• Reliable calculations of Doppler broadened reaction cross sections
• Permits inter - and extrapolation into regions were no experimental data are available
• Permits prediction of reaction cross sections for isotopes not directly accessible to experiments
9Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx
Parameterisation of neutron cross sections by nuclear reaction theory
• Thermal : R - Matrix
• RRR : R - Matrix (SLBW, Reich-Moore)
• URR : Statistical Models (Hauser – Feshbach + WF)
• High : Optical Model, precompound, direct reactions, …
10Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx
Parameterisation of neutron cross sections by nuclear reaction theory
URRStatistical Models
Res. Par.ERj , n,j , ,j , Jj , R
High EnergyOptical Models
Thermal
RRRR-Matrix
Level Statistics + RD0 , So , < >
)E,,g(f RjjnjJth
Average Par.Do,1 , So,1 , < >, R
Exp. Data
Exp. DataExp. Data
Exp. Data
11Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx
Neutron energy spectrum
10-2 100 102 104 106 1080.0
0.1
0.2
0.3
(d n
/ d
lnE
n)
/ (c
m-2 s
-1)
fast thermal
Neutron Energy / eV
Reactor ADS : Ep = 600 MeV
10-2 100 102 104 106 1080.0
0.1
0.2
0.3
0.4
(d n
/ d
lnE
n)
/ (c
m-2 s
-1)
ADS-spectrum for Ep = 600 MeV
Neutron Energy / eV
12Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx
Importance of resonance structure
3.7 3.8 3.9 4.0 4.1 4.20.0000
0.0002
Tra
nsm
issi
on
Neutron Energy / MeV
Transmission (dFe = 40 cm)
0
2
4
6
8
tot
/ b
arn
IRMM 1993 ENDF/ B-VI
natFe + nGELINA
13Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx
Resonances : compound nucleus reactions
n + X C* Y + rEntrance channel Compound nucleus Exit channel
14Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx
• Two step process
(1) Formation of compound nucleus C*
(2) Decay of compound nucleus Pr
• Partial cross section
Bohr’s hypothesis : compound nucleus reactionResonance part of cross section
22
Rn
n2n
Jn*C)2(EEk
gE
,...)f,,nr(r
r
,...)f,,nr(P rr
r*Cr P
AX
-Sn
En
A+1X
c*
E*
AX +n
nn* E
1A
ASE
15Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx
nJ2
R
o gk
4
133 134 135
0
4000
8000
Eo
n
o
n
n /
bar
n
Neutron Energy / eV133 134 135
0
4000
8000
Eo
o
/
bar
n
Neutron Energy / eV
ER = 134 eVn = 0.093 eV = 0.106 eVJ = 1-
= 0gJ = 3/4
133 134 135
0
4000
8000
t
o
Eo
t /
ba
rn
Neutron Energy / eV
e.g. 109Ag s-wave at ER = 134 eV(ER, n, , J
(), )
tot
tot
/ bar
n
ER
ER
ER
16Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx
Compound nucleus reactions
• No capture without scattering
• Relative contribution of n and to tot may be different
• Boundaries of the resonance region differ
• Not only resonances (see 58Fe + n)
10-2 100 102 10410-3
10-1
101
103
105
t
n
Cro
ss s
ectio
n /
barn
Neutron Energy / eV
197Au + n
10-2 100 102 104 10610-4
10-2
100
102
104
t
n
Cro
ss s
ectio
n /
barn
Neutron Energy / eV
56Fe + n
tot
tot
17Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx
SLBW for low energy s-wave(n,n) and (n,)
• (n,)
• (n,n)
• Total
22
Rn
n2n
Jn)2(EEk
gE
2J22
Rn
Rnn
nJ22
Rn
nn2n
Jnn R4g)2(EE
R)EE(
k
4g
)2(EEkgE
2J22
Rn
Rnn
nJ22
Rn
n2n
Jntot R4g)2(EE
R)EE(
k
4g
)2(EEkgE
n
)1I2(2
1J2gJ
fmA23.1R 31
(ER, n, , J(), )
18Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx
Interference term s-wave <---> p-wave ( > 0)
3.350 3.355 3.360 3.3650
400
800
1200
Neutron Energy / keV
p-waveE
0 = 3357.1 eV
n = 0.240 eV
= 0.087 eV
tot
/ ba
rn
64 66 68
0
10
20
30
40
Neutron Energy / keV
tot
/ ba
rn
E0 = 65.954 keV
n = 93.0 eV
= 1.3 eV
s-wave
(ER, n, , J(), )
n
22n
J22Rn
nnRn2n
J22on
nn2n
Jntot sink
4g
)2(EE
)2sin()EE(
k
2g
)2(EE
)2cos(
kgE
19Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx
Ideal experiment
• In ideal conditions, without any instrumental resolution broadening, we can determine o/ and from one experiment.
and n o = f(gJ, n, )
However,
• Due to instrumental limitations and Doppler effect it is in most cases impossible to determine and o/
• Due to the instrumental limitations the effective experimental observable is :the area of a resonance
133 134 135
0
4000
8000
Eo
o
/
ba
rn
Neutron Energy / eV
ER
20Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx
3340 3350 3360 3370
0
20
40
60
Neutron Energy / keV
0.0
0.2
0.4
0.6
0.8
1.0
Experimental observables
• Transmission
• Capture
nJthick,t ngA
n
Jthin, ngA
nJthin,t ngA
n is the number of nuclei per unit area
Neutron energy / eV
Rae et al., Nucl. Phys. 5 (1958) 89F. Fröhner et al., ND1966, p. 55
totneT
21Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx
Capture + Transmission
n n
Ideally : combine thin capture measurements with transmission measurements on samples with different thicknesses
n
JngA nJgn Jgn• Capture
nJgn thick,tA nJgn
thin,tA nJgn • Transmission nJgn
Rae et al., Nucl. Phys. 5 (1958) 89F. Fröhner et al., ND1966, p. 55
more sensitive to small resonances
22Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx
Example: 109Ag s-wave at 5.2 eV
n / meV
gn = 3/4 gn = 1/4
12.7 38.0
I = 1/2-, i = 1/2 , and = 0 J = 0- or J = 1-
gJ = 1/4 or gJ = 3/4
nJ2n
2
thin,t ngk
2A
n / meV
/ meV gn = 3/4 gn = 1/4
50 37.8 113.5
100 18.9 56.7
150 12.6 37.8
200 9.5 28.4
300 6.3 18.9
400 4.7 14.2
nJn
thick,t ngk
2A
Thin Sample Transmission
n = 1.39 10-5 at/bAt,thin = 0.106 eV
Thick Sample Transmission
n = 4.74 10-4 at/bAt,thick = 1.039 eV
gJ = 3/4 gJ = 1/4 gJ = 3/4 gJ = 1/4
Rae et al., Nucl. Phys. 5 (1958) 89
(gJ n 9.5 meV , 150 meV, =0)
23Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx
Resonance Area Analysis e.g. 109Ag 5.2 eV
0 100 200 300 400 5000
10
20
c2
min = 3.2
At,thin
At,thick
A A
n
g = 3/4
n /
meV
/ meV
ER = 5.2 eV, n = 12.7 (0.23) meV , = 149.0 (7.8) meV, gJ = 3/4
0 100 200 300 400 5000
25
50g = 1/4
c2
min = 75
At,thin
At,thick
A A
n
n /
meV
/ meV
gJ = 3/4 gJ = 1/4gJ = 3/4
Rae et al., Nucl. Phys. 5 (1958) 89
(ER, n, , J(), )
24Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx
10-2 100 10210-2
100
102
104
106
109Ag(n,)
EO = 5.2 eV
th = 91 b
s-wave p-wave
/
bar
n
Neutron Energy / eV
Neutron widths-wave <----> p-wave ( > 0)
n depends on En : due to the centrifugal-barrier penetrability, which depends on the angular momentum quantum number of the incoming neutron and En
(penetration probability depends on )
• s-wave ( = 0)
• p-wave ( = 1)
cross section at 0.025 eV (Thermal)
eV1
E)E( n0
nnn
22n
22nn1
nnnak1
ak
eV1
E)E(
N
1j2
Rj
rjonjJ2
6thr
E
g
A
1A10.099.4
22
Rn
n2n
Jn)2(EEk
gE
25Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx
th and contribution of s-wave resonances
•
• Additional contribution from bound states (negative resonances)
N
1j2
Rj
jonjJ
2
A
A6th0E
th
E
g
m
1m10.099.4
10-3 10-1 10110-2
100
102
104
106 , total
for Er = 1 eV
for Er = - 1 eV
(n,)
/ bar
n
Neutron Energy / eV
AX
-Sn A+1X
c*
E*
AX +n
26Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx
Determination of resonance parameters
• SLBW and Resonance Area Analysis– Instructive– Principles remain valid !
• Resonance Shape Analysis (RSA)
(R- Matrix : theory)
– Extension of RRR– Direct treatment of broadening effects (Resolution & Doppler)– Direct treatment of multiple scattering effects (capture data)– Reduction of uncertainties
– SAMMY ( N. Larson) S. Marrone– REFIT ( M. Moxon) Summer School on Neutron Resonance Analysis
2- 6 June 2008, IRMM Geel
27Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx
TOF - measurements
• Introduction
• TOF - measurements
– TOF-principle– Neutron production– Resolution– Experimental observables
• Transmission experiments
• Examples
28Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx
Cross section measurements
• Thermal– Reactor– TOF-facilities
• Resolved Resonance Region– TOF-facilities (photonuclear reactions, spallation sources)
• Unresolved Resonance Region– TOF-facilities– VdG + TOF– Filtered beams (+ TOF)– Activation
• High Energy Region– TOF-facilities (spallation sources)– Activation– VdG (< 20 MeV)– Cyclotron
N. Colonna
29Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx
TOF - measurements
• Photonuclear reactions– GELINA (n,tot) + (n,), (n,f), (n,p), (n,)– ORELA (n,tot) + (n,), (n,f), (n,p), (n,)– RPI (+ filtered) (n,tot) + (n,), (n,f), (n,n)– POHANG (KAERI) (n,tot)– KURRI (n,tot) + (n,)
• Spallation sources (N. Colonna)– n_TOF (n,), (n,f)– LANSCE (n,tot) + (n,), (n,f)
30Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx
• Velocity from TOF
• Resolution L
• Neutron flux L
TOF - measurements
nn t
Lv
2
2
2n
2n
n
n
L
L
t
t
v
v
2n L
1)L(
1
)c/v(1
1cmE
2n
2nn
150
MeV
LIN
AC Sample
Flight pathUdepl.
fn’
tot
tn
Lvn
31Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx
TOF-facility : GELINA
• Time-of-flight facility
• Pulsed white neutron source (5 meV < En < 20 MeV)
• Multi-user facility with 10 flight paths (10 m - 400 m)
• The measurement stations have special equipment to perform:
– Total cross section measurements– Partial cross section measurements
Pulse Width : 1ns
Frequency : 50 – 800 Hz
Average Current : 4.7 – 75 A
Neutron intensity : 1.6 1012 – 2.5 1013 n/s
32Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx
GELINA : neutron production
NEUTRONMODERATOR
ELECTRONBEAMLINE EXIT
NEUTRONTARGET
NEUTRONFLIGHT PATHS
• e- accelerated to Ee-,max ≈ 140 MeV
• (e-, ) Bremsstrahlung in U-target
(rotating & cooled with liquied Hg)
• ( , n) , ( , f ) in U-target
• Low energy neutrons by water
moderator in Be-canning
33Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx
Compression Magnet
140 MeV
80 MeV
10 ns 1 ns
100 A
10 A
E
qc
2B
qc
E
B
1
eq;pcE;q
pB
2
compressed pulse length ~ 1 ns
E = 60 MeV = 10 ns
34Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx
GELINA : neutron production
SHIELDING for MODERATED SPECTRUM
SHIELDING for FAST SPECTRUM
10-2 100 102 104 106102
103
104
105 GELINA 30 m 800 Hz
Exp. Mod. Fast
MCNP Mod. Fast
dn/
dlnE
n /
(cm
-2 s
-1)
Neutron Energy / eV
Flaska et al.,NIM A , 531, 394 (2004)
35Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx
ORELA : neutron production
10-3 10-2 10-1 100 101 102 103 104 105 106 107 108105
106
107
108
109
1010
1011
OR
EL
A F
lux
n/s
ec/s
r/kW
Cap
abili
ties
Neutron Energy (eV)
36Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx
Resolution
T
– Initial burst width
– Time jitter of detector
– Electronics
L
– Neutron transport in target and moderator
– Neutron transport in the detector or sample
2
2
2
2
n
n
L
L
T
T
v
v
Detector
L0
Resolution
L = L0 + L’m
En
e- beam
L’m
R(L’m)
37Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx
Resolution: Monte Carlo simulations
-5 0 5 10 1510-4
10-3
10-2
10-1
100E
n = 10000 - 30000 eV
Distance / cm
-5 0 5 10 1510-4
10-3
10-2
10-1
100
MCNP (PhD M. Flaska) Coceva
En = 100 - 1000 eV
Distance / cm-5 0 5 10 15
10-4
10-3
10-2
10-1
100 En = 1 - 10 eV
Res
pons
e /
(1/
cm)
Distance / cm
Flaska et al.,NIM A , 531, 394 (2004)
38Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx
Resolution : experimental verification
3.34 3.35 3.36 3.370
20
40206Pb(n,)
C
aptu
re Y
ield
/ B
arn
FWHM
= 3.89 eV
R = 3.25 eV
D = 2.24 eV
t = 0.34 eV
Neutron Energy / keV
Exp RSA (REFIT) Resolution (Coceva)
34.1 34.2 34.3 34.40
1
256Fe(n,)
FWHM
= 42.88 eV
R = 42.29 eV
D = 6.84 eV
t = 1.96 eV
Exp. RSA (REFIT) Resolution (Coceva)
Neutron Energy / keV
39Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx
Direct spectrumModerated spectrum
(n,) NIM, A577 (2007) 626
(n,tot) NP A 773, 173 (2006)
(n,f) and (n,cp) NSE 156, 211 (2007)
(n,n’) NP A 786, 1 (2007)
Measurement Stations
40Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx
Experimental observables
Reaction Measurements Transmission
Detector
Detector
totneT rrrrr AYC
41Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx
Transmission
• Incoming flux cancels
• Detection efficiency cancels
• Good geometry
Direct relation between T and tot
Reaction
r Neutron fluence rate
r Detection efficiency
• Ar Effective area
• Yr Reaction Yield
Beam fraction undergoing (n,r)
Complex relation between Cr and Yr
Yr related to r
totn
out
in eC
CT rrrrr AYC
Experimental observables
42Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx
Reaction yield : thin Sample
• Thin sample, no scattering only self-shielding
Yr = f(r , tot)
• Infinitely thin sample
Direct Relation : Yr <--> r
t
rnr )e1(Y tr
rrt
rσnthin,r n
σ
σe1Y tr
n
x
n(x)
43Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx
n nn’
nn’
n’’
Yo Y1 Y2
j
jYY
tot
n
n
)e1(nY
tot
2
22
n
A2
nA
nn
'n sin
m
mcos
mm
mEE
Correction for self-shielding and multiple scattering requires
tot & n
Reaction yield : thick sample
44Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx
Transmission experiments
• Introduction
• TOF – measurements
• Transmission experiments
– Principle– Experimental set-up– Facilities– Data reduction
• Applications
45Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx
Transmission : principle
– All detected neutrons have traversed the material– Neutrons scattered in the target do not reach the detector
Homogeneous sample
Importance of collimation (good geometry!)
totneT
sample detector
46Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx
Neutron DetectorLithium-glas scintillator
• Neutrons interact with lithium via 6Li(n,)t
• The charged particles create fluorescence
in the scintillator material
• The light is reflected to the entrance
window of the photomultiplier
• The light is transformed into electrons in
a photocathode
• The electron signal is amplified in the
photo-multiplier tube
6Li(n,t) Scintillator + Photomultiplier
47Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx
Transmission detector
Time Resolution
6Li(n,t) Scintillator + Photomultiplier
0 1 2 3 410-3
10-2
10-1
100
101
Res
pons
e / (
1/cm
)
MCNP REFIT
En = 10 eV
Distance / cm
48Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx
Transmission: experimental set-up
Sample & Background Filters Detector
Kopecky and Brusegan, Nucl. Phys. A 773 (2006) 173Borella et al., Phys. Rev. C 76 (2007) 014605
Low energy : 6Li(n,t) Li-glassHigh energy : H(n,n)H Plastic scintillator
Detector stations at GELINAModerated : at 30 m, 50 m, (100 m, 200 m)Fast : at 400 m
49Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx
Transmission
103 104 105 10610-2
10-1
100
101
102
103
Total BKG fit BKG points
SAMPLE OUT
Re
spo
nse
/ (1
/ns)
TOF / ns
103 104 105 10610-2
10-1
100
101
102
103
Total BKG fit BKG points
SAMPLE IN
Re
spon
se /
(1/n
s)
TOF / ns
0 20000 40000 60000 800000.0
0.2
0.4
0.6
0.8
1.0
Tra
nsm
issi
on
Neutron Energy / eV
'out
'out
'in
'in
BC
BCT
50Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx
Transmission
Sample out
(1) Dead time correction
(2) Background subtraction
'out
'out
'in
'in
TexpBC
BCNT
n)E(
nnTnexp dEe)E,T(R)T(T ntot
Sample in
(1) Dead time correction
(2) Background subtraction
RRRResonance shape analysis
URRCorrection for resonance structure
...)var2
n1(ee tot
2nn tottot
totnexp eT
51Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx
Resonance analysis : 241Am
0.1 1 10
-4
0
4
Res
idua
ls
Neutron Energy / eV
0.0
0.5
1.0
Exp. REFIT
Tra
nsm
issi
on
52Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx
ORELA : transmission + capture
Guber et al., Phys. Rev C 65 (2002) 058801
35,37Cl + n
Transmission- at 20, 80 and 200 m- 6Li-glass scintillator
Capture- at 40 m- C6D6-detectors
Measurements on over 180 nuclides: ORELA measurements have contributed to ~80% of U.S. Evaluated Nuclear Data File (ENDF/B) evaluations
53Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx
RPI : transmission + capture
Transmission- at 15, 25 and 100 m- 6Li-glass scintillator
Capture- at 30 m- 16 segment NaI(Tl)-scintillator
Drindak et al., Nucl. Sci. Eng. 154 (2006) 294
Leinweber et al.,Nucl. Sci. Eng. 134 (2000) 50
Nb
54Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx
POHANG : transmission
Transmission- at 10 m- 6Li-glass scintillator (1.5 cm thick)
Lee et al., Radiat. Meas. 35 (2002) 321
55Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx
LANSCE : transmission in high energy region
Transmission- at 38 m- plastic scintillator (1.27 cm thick)
Abfalterer et al., Phys. Rev. 63 C (2001) 044608
56Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx
Applications
• Introduction
• TOF – measurements
• Transmission experiments
• Applications
– Doppler– Thermal region– RRR & URR– High energy region
57Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx
Doppler measurements
Temperatures from 10 K - 300 K
19 20 21 220.7
0.8
0.9
1
Temperature 15K 300K
Tra
nsm
issi
on F
acto
r
Neutron Energy / eV
240Pu : target thickness = 8.7 10-5 at/b
ER = 22.45 eV
58Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx
Optimise the U - Pu fuel cycle
More accurate nuclear data are needed for:
1) Tendency to operate conventional nuclear power plants at increased fuel burn-up
2) Fuel cycles based on reprocessed fuel(closed fuel cycle)
3) Spent fuel storages (ORNL – RADWASTE)
M. Salvatores, ND2002, J. Sci. & Techn. 2 (2002) p. 4F. Storrer et al., ND2002, J. Sci. & Techn. 2 (2002) p. 1357NEA High Priority List, March 2001
< 2-3%
1 & 2 : Collaboration with CEA Saclay (F)
3 : Collaboration with ORNL (US)
Nuclide Priority Level
Storrer et al.
Burnup
Salvatores
Reprocessing 103Rh 1 133Cs 1 155Gd 1 147Sm 1 149Sm 1 152Sm 1 143Nd 2 1 145Nd 1 153Eu 2 1 155Eu 1
59Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx
103Rh: Thermal region
(n,) at 25.3 meV
WF : 142.0 (1.5) b
1.0 % normalization
0.5 % uncorrelated
Counts : 143.3 b
0.01 0.1 1 1010-3
10-2
10-1
100 Experiment REFIT
Cap
ture
Yie
ld
Neutron Energy / eV
Transmission: 50 m 100 Hz Capture : 15 m 40 Hz
n = 3.35 10-4 at/b
n = 1.87 10-3 at/b
ER = 1.260 eV
n = 0.464 meV
= 156.0 meV
gJ = 3/4D 35 meVR < 5 meV
60Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx
55Mn Transmission measurements at 50 m
10000 20000 30000 40000 50000
-4
4
Re
sid
ua
ls
Neutron Energy / eV
0.2
0.4
0.6
0.8
1.0
Tra
nsm
issi
on
10000 20000 30000 40000 50000
-4
0
4
Sputtering target n = 1.92 10-2R
esi
ud
als
0.2
0.4
0.6
0.8
1.0
Tra
nm
smis
sio
n
Mn powder n = 9.94 10-3
100 1000 10000
-4
4
Res
idua
ls
Neutron Energy / eV
0.2
0.4
0.6
0.8
1.0
Exp. REFIT
Mn + S powder n = 1.53 10-3
Tra
nsm
issi
on
100 1000 10000
-4
0
4
Res
iuda
ls
0.2
0.4
0.6
0.8
1.0
Tra
nmsm
issi
on
Mn + S powder n = 4.35 10-4
61Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx
IAEA CRP: Thorium – Uranium Fuel Cycle
Resonance parameters (RRR & URR) for 232Th + n
Facility Measurement
Type
Flight Path
Length
Target Thickness
at/b
ORELA Transmission 180 m 1.68 10-4 14.00 10-4 38.70 10-4 193.1 10-4
GELINA Transmission 50 m 8.00 10-4 34.0 10-4 61.0 10-4
GELINA Capture 15 m 15.8 10-4 60 m 34.0 10-4
n-TOF Capture 200 m 41.0 10-4
62Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx
232Th Resolved Resonance Region
Simultaneous analysis of
transmission and capture
• Determine R
• Determine
• Determine n
• Verify gJ
Examples
0.0
0.5
1.0
Cap
ture
Yie
ld
0 200 400 600 800 10000.0
0.5
1.0
Tra
nsm
issi
on
Energy / eV
63Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx
Scattering radius : transmission with thick sample
R’ = 8.9 fm R’ = 9.5 fm
Neutron Energy / eV Neutron Energy / eV
200.0199.0 199.0 200.0
Tra
nsm
iss
ion
Interferencepotres
2J22
Rn
Rnn
nJ22
Rn
n2n
Jntot R4g)2(EE
R)EE(
k
4g
)2(EEkgE
232Th + n
64Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx
Statistical factor : simultaneous analysis of capture and transmission data
7.22
c
Neutron Energy / eV Neutron Energy / eV
Cap
ture
Yie
ld
Cap
ture
Yie
ldT
ran
smis
sio
n
Tra
nsm
iss
ion
gJ = 2gJ = 1 2.1
2
c
200.0199.0 200.0199.0232Th + n
65Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx
Average radiation width from capture datawith REFIT
0 250 5000.0
0.1
0.2
Cap
ture
Yie
ld
Neutron Energy / eV
ORELA (Transmission) : <> = 25.10 (0.40) meV
IRMM (Capture) : <> = 25.12 (0.06) meV
232Th(n,)
66Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx
Evaluation in URR and high energy region
0 50 100 15010
15
20
25 Capote Iwasaki et al. Poenitz et al. Uttley et al. Vertebnyj et al. Kobayashi et al. Grigor'ev et al.
< n
,tot>
/ b
arn
Neutron Energy / keV
0 50 100 15060
70
80
90
100
This work Capote
(< n>E
1/2 )
/
(bar
n eV
1/2 ) Macklin and Winters
Kobayashi et al. Aerts et al. Borella et al. Average
Neutron Energy / keV
Sirakov et al., Annals of Nuclear Energy, accepted 2008Capote et al., Phys. Rev. C 72 (2005) 064610Soukhovitskii et al., Phys. Rev. C 72 (2005) 024604
67Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx
10-3 10-1 101 103 105 10710-5
10-3
10-1
101
103
t
Cro
ss s
ectio
n / b
Neutron Energy / eV
206Pb + n : new evaluation in RRR
Thermalneutronenergy
BNC
RRR
GELINA
68Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx
60 64 68 720.5
0.6
0.7
0.8
0.9 Measurement FIT
Tra
nsm
issi
on
Neutron Energy / keV
Scattering radius from transmission of s-wave at 66 keV
R = 9.55 (0.02) fm
R = 9.46 (0.15) fm (Mughabghab)
Interferencepotres
2J22
Rn
Rnn
nJ22
Rn
n2n
Jntot R4g)2(EE
R)EE(
k
4g
)2(EEkgE
Borella et al., Phys. Rev. C 76 (2007) 014605
206Pb+n
69Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx
Determination of statistical factor gJ
thin <--> thick transmission
95.01g2
J c
25000 25500 260000.2
0.4
0.6
0.8
1.0t=3.00 x 10-2 at/b Measurement
FIT
Tra
snm
issi
on
Neutron Energy / eV
0.2
0.4
0.6
0.8
1.0 Measurement FIT
Tra
snm
issi
on
t = 1.60 x 10-2 at/b
25000 25500 260000.2
0.4
0.6
0.8
1.0t=3.00 x 10-2 at/b Measurement
FIT
Tra
snm
issi
on
Neutron Energy / eV
0.2
0.4
0.6
0.8
1.0t = 1.60 x 10-2 at/b Measurement
FIT
Tra
snm
issi
on
25.22g2
J c
nJthin,t ngA
nJthick,t ngA
)1I2(2
1J2gJ
206Pb+n
70Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx
Final RSA results: 206Pb+n
• 304 resonances observed
• 221 resonances in evaluated files
• R = 9.54 (0.02) fm
• En, n from transmission < 80 keV : IRMM data (Borella et al.)> 80 keV : ORELA data (Horen et al.)
• E0, up to 620 keV (Borella et al.)(before up to 200 keV )
• fE1 and fM1 from unfolding of C6D6 spectra
1E-5
1E-3
0.1
Yie
ld
Capture
Horen et al., Phys. Rev. C 24 (1981) 1961, C20 (1979) 478Borella et al., Phys. Rev. C 76 (2007) 014605Rochman and Koning, Nucl. Instr. Meth. A (2008), doi:10.1016/j.nima.2008.02.003
0 20000 40000 60000 800000.0
0.2
0.4
0.6
0.8
1.0
Transmission
Tra
nsm
issi
on
Neutron Energy / eV
71Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx
High energy region + Optical Model
LANSCEFinlay et al., Phys. Rev. C 47 (1993) 237Abfalterer et al., Phys. Rev. C 63 (2001) 044608
72Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx
Total cross section + Optical model
Deb et al., Phys. Rev. Lett. 86 (2001) 3248
73Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx
Importance of transmission data
• Easiest and most accurate measurement
• No need for a standard cross section !
• Resonance region– parity assignment– thick & thin measurements result in (gJ, n) and R (scattering radius)– partial cross section data complementary to transmission for << n
– normalization of capture data (n<< )
tot data are a prerequisite to good partial cross section analysis(Fröhner, JEF Report 18)
– self-shielding and multiple scattering corrections– neutron sensitivity of the detectors
• Total cross section + optical model (predictive power)
• High resolution transmission data for shielding calculations