Study of Nuclear Fission Process Through Gamma-Ray Spectrometry
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PHENIICS Fest, Orsay, 30 May 2017
M
ICHAŁ
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ĄPAŁA
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Motivations
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Experimental data
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EXILL experiment
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Preliminary results
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Ba – Kr
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Conclusions
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M. Rapala, IRFU/DPhN/LERN
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May 30, 2017
M. Rapala, IRFU/DPhN/LERN
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May 30, 2017
Motivations
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May 30, 2017
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Result of gamma-ray energy
deposition
HTMR Asia Development Limited,
http://www.htmr-asia.com/en/product.php?id=27 (2014)
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May 30, 2017
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Result of gamma-ray energy
deposition
S. Sen et al., Nuclear Engineering and Design Vol. 293,
Pages 323-329 (2015)
HTMR Asia Development Limited,
http://www.htmr-asia.com/en/product.php?id=27 (2014)
Areva , UK-EPR, Fundamental safety overview Vol. 1,
Chapter A, Page 63
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Almost 100% of total heating in the reflector
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May 30, 2017
A-C. Colombier et al., EPJ Web of Conferences 42, 04001 (2013)
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May 30, 2017
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May 30, 2017
What we want to study:
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Fission process
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Prompt gamma-ray cascade in fission fragments
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May 30, 2017
Courtesy of J.F. Lemaître, SPhN, IRFU, DRF, CEA Saclay
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May 30, 2017
The continuum
The part partially
completed from
the models
The experimental
nuclear levels
O. Litaize et al., ND-2016, Bruges
Main questions concerning de-excitation process:
What happens after the scission point?
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May 30, 2017
How is the excitation energy
shared between the two
fragments?
What are the initial spin
distributions?
Are they correlated?
What is the process that
generates high spin in the
fragment?
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Simulates fission fragments de-excitation
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May 30, 2017
M. Rapala, IRFU/DPhN/LERN
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May 30, 2017
Experimental data
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May 30, 2017
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Array of Ge-detectors around a fissile target in a
intense cold neutron beam
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15 days with
235
U (575 μg/cm
2
) + Sn/Zr
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5 days with
235
U (675 μg/cm
2
) + Be
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15 days with
241
Pu (300 μg/cm
2
) + Be
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8 EXOGAM clovers + 2
ILL clovers + 6 GASP
Ge + BGO shielding
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Without LaBr
3
detectors
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Analysis of
235
U data
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May 30, 2017
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Triple-
coincidence
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Analysis software
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Choosing gates
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Selecting fission
fragments
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Fitting spectra in
triple-
coincidence
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Calculating relative
intensity of the
gamma-ray transition
and anticipation of
the uncertainty
propagation
M. Rapala, IRFU/DPhN/LERN
Page 16
May 30, 2017
Triple-
coincidence in practice
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May 30, 2017
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May 30, 2017
Urban et al., Nucl. Phys A 613 (1997) 107
Rząca-Urban et al., Eur. Phys. J. A 9 (2000) 165
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May 30, 2017
Urban et al., Nucl. Phys A 613 (1997) 107
Rząca-Urban et al., Eur. Phys. J. A 9 (2000) 165
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May 30, 2017
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Cleaner spectrum
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Still high background and many contaminants
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May 30, 2017
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Clean spectrum
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Reduced background
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Clearly visible peaks
92
Kr
142
Ba
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May 30, 2017
Preliminary Results
M. Rapala, IRFU/DPhN/LERN
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May 30, 2017
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Gamma-ray cascade
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May 30, 2017
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T. Materna et al., accepted for publ. In EPJ Web of Conferences (2017)
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Gamma-ray cascade
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May 30, 2017
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T. Materna et al., accepted for publ. In EPJ Web of Conferences (2017)
T. Materna et al., accepted for publ. In EPJ Web of Conferences (2017)
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Gamma-ray cascade
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T. Materna et al., accepted for publ. In EPJ Web of Conferences (2017)
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Gamma-ray cascade
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Good agreement for
low spin transitions
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High spin transitions
overestimated by
FIFRELIN code
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May 30, 2017
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Gamma-ray cascade
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Good agreement for
low spin transitions
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High spin transitions
overestimated by
FIFRELIN code
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Probably wrong
estimation of a mean
value of the fission
fragment spin
distribution
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May 30, 2017
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Dependence on a complementary fragment (neutron
evaporation)
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May 30, 2017
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Dependence on a complementary fragment (neutron
evaporation)
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May 30, 2017
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In FIFRELIN initial spin is
constant
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May 30, 2017
J [ħ]
E
ex
[MeV]
4 neutrons
3 neutrons
2 neutrons
1 neutron
0 neutrons
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In FIFRELIN initial spin is
constant
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Neutron evaporation follows
the mean value of the level
density distribution
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May 30, 2017
J [ħ]
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ex
[MeV]
4 neutrons
3 neutrons
2 neutrons
1 neutron
0 neutrons
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In FIFRELIN initial spin is
constant
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Neutron evaporation follows
the mean value of the level
density distribution
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With more evaporated
neutrons less high spin
transitions are produced
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May 30, 2017
J [ħ]
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ex
[MeV]
4 neutrons
3 neutrons
2 neutrons
1 neutron
0 neutrons
Conclusions
M. Rapala, IRFU/DPhN/LERN
Page 34
May 30, 2017
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Systematic study of the prompt gamma-ray cascades
of the fission fragments
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Triple-
coincidence technique
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Analysis made on a few (the most abundant) fission fragment
pairs
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Results will help to improve simulations of gamma heating in
nuclear reactors
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Benchmarking the MC simulation code FIFRELIN
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Comparison to FIFRELIN simulation results
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Some effects need further investigation
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May 30, 2017
T. Materna
1
, A. Letourneau
1
, A. Marchix
1
, O. Litaize
2
, O.
Sérot
2
, D. Regnier
2
, W. Urban
3
, A. Blanc
4
, M. Jentschel
4
, U.
Köster
4
, P. Mutti
4
, T. Soldner
4
, G. Simpson
5
,
Călin A. Ur
6
, and
G. de France
7
1
Irfu, Université Paris-Saclay, Gif-sur-Yvette, France
2
CEA, DEN, DER, Cadarache, Saint-Paul-lez-Durance, France
3
Faculty of Physics, University of Warsaw, Warsaw, Poland
4
Institut Laue-Langevin, Grenoble, France
5
LPSC, CNRS/IN2P3, Grenoble, France
6
INFN, Legnaro, Italy
7
GANIL, Caen, France
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May 30, 2017
CEA Saclay
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Data analysis technique
development
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Data analysis
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Gathering information about
gamma-ray cascade
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Comparing experimental data
with simulation results
CEA Cadarache
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Comparing experimental data
with simulation results
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Testing different parameter
setups
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Improving simulation code
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May 30, 2017
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Too high uncertainty
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Too high statistical error
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Peak shape too complicated
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Problems with detectors energy resolution and tails
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Our peak looks like triple Gaussian + Compton
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Additional peaks needed to reproduce the correct shape
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Wrong volume of the peaks
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Contaminants included in the gates
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May 30, 2017
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May 30, 2017
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Europium source data used for calibration
152
Eu
152
Gd or
152
Sm
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Three types of detectors with different performance
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Europium source data used for calibration
152
Eu
152
Gd or
152
Sm
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Three types of detectors with different performance
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Total coincidence efficiency formula simplification
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May 30, 2017
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Europium source data used for calibration
152
Eu
152
Gd or
152
Sm
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Three types of detectors with different performance
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Total coincidence efficiency formula simplification
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May 30, 2017
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Europium source data used for calibration
152
Eu
152
Gd or
152
Sm
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Three types of detectors with different performance
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Total coincidence efficiency formula simplification
Difference lower than 2% in range between 100keV to 1.5MeV
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May 30, 2017
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Europium source data used for calibration
152
Eu
152
Gd or
152
Sm
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Three types of detectors with different performance
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Total coincidence efficiency formula simplification
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Correction of true coincidence effect
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May 30, 2017
Energy [keV]
Efficiency [%]
Energy [keV]
Efficiency [%]
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91
Zr(n,
)
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92
Zr peak at 1405 keV
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FWHM equal to 3.7 keV
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Chi
2
/NDF equal to 1.7
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May 30, 2017
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Peak shape
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Not a simple Gaussian
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Gating with subtracted background
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Choosing correct background
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Peak/Background ratio
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Gates width
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Contaminants in the gates
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Gates width
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May 30, 2017
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Page 47
May 30, 2017
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Better value of the peak/background ratio
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2 bins gate width
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1 bin gate width
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Page 48
May 30, 2017
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Better
visibility of
contaminants
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More precise
contamination
positioning
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More precise
results
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Lower
uncertainty
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2 bins gate width
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1 bin gate width
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Dependence on a complementary fragment (neutron
evaporation)
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Page 49
May 30, 2017
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Effect caused by dependence
between excitation energy and
level density
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Dependence on a complementary fragment (neutron
evaporation)
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Page 50
May 30, 2017
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Effect caused by dependence
between excitation energy and
level density
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More evaporated neutrons
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Lower excitation energy of the
fission fragments after
neutron evaporation
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Lower probability of high-spin
transition production
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May 30, 2017
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May 30, 2017
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May 30, 2017
3
5
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5
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Page 54
May 30, 2017
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Clean spectrum
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Reduced background
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Clearly visible peaks
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Three-dimensional histogram
→
γγγ
-cube
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Page 55
May 30, 2017
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Fixed time window
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Transitions coming
within the time
window limit are
considered to be
in coincidence
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Selection of fission fragments
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Gating (with back ground subtraction)
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Identification of peaks
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Page 56
May 30, 2017
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Selection of fission fragments
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Gating (with back ground subtraction)
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Identification of peaks
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Fitting of the peaks
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Fitting with simple Gaussian
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Fit integration
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Calculation of normalized intensities of the peaks
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Normalized to the most intense transition of the particular
fission fragment
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Comparison to other experimental data and FIFRELIN
simulation results
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M
E
M. Rapala, IRFU/DPhN/LERN
Page 57
May 30, 2017
C
O
N
T
E
X
T
O
F
T
H
E
T
H
E
S
I
S
M. Rapala, IRFU/DPhN/LERN
Page 58
May 30, 2017
C
E
A
,
D
P
h
N
,
I
R
F
U
,
S
a
c
l
a
y
C
O
N
T
E
X
T
O
F
T
H
E
T
H
E
S
I
S
M. Rapala, IRFU/DPhN/LERN
Page 59
May 30, 2017
C
E
A
,
D
E
N
,
D
E
R
,
C
a
d
a
r
a
c
h
e
C
E
A
,
D
P
h
N
,
I
R
F
U
,
S
a
c
l
a
y
•
Simulates fission fragments de-excitation
F
I
F
R
E
L
I
N
M
O
N
T
E
-
C
A
R
L
O
S
I
M
U
L
A
T
I
O
N
C
O
D
E
M. Rapala, IRFU/DPhN/LERN
Page 60
May 30, 2017
Data obtained from the EXILL experiment
M. Rapala, IRFU/DPhN/LERN
Page 61
May 30, 2017
Problems with analysis and solutions
•
Peak shape
•
Not a simple Gaussian
S
P
E
C
T
R
A
F
I
T
T
I
N
G
P
R
O
B
L
E
M
S
M. Rapala, IRFU/DPhN/LERN
Page 62
May 30, 2017
S
P
E
C
T
R
A
F
I
T
T
I
N
G
P
R
O
B
L
E
M
S
-
P
E
A
K
S
H
A
P
E
M. Rapala, IRFU/DPhN/LERN
Page 63
May 30, 2017
•
Simple Gaussian
data
fit function
integrated over
the bin
fit function
S
P
E
C
T
R
A
F
I
T
T
I
N
G
P
R
O
B
L
E
M
S
-
P
E
A
K
S
H
A
P
E
M. Rapala, IRFU/DPhN/LERN
Page 64
May 30, 2017
•
Simple Gaussian
data
fit function
integrated over
the bin
fit function
•
Bad resolution
•
Sum of all detectors
•
Sum of all runs
•
Compton – tails
•
91
Zr(n,
),
92
Zr(n,
)
•
A
DJUSTED
ON
92
Z
R
AND
93
Z
R
CLEAN
PEAKS
•
Fit function
•
S
UM
OF
3 G
AUSSIANS
•
Same center
•
C
OMPTON
–
TAILS
E
X
I
L
L
R
E
S
O
L
U
T
I
O
N
M. Rapala, IRFU/DPhN/LERN
Page 65
May 30, 2017
S
P
E
C
T
R
A
F
I
T
T
I
N
G
P
R
O
B
L
E
M
S
-
P
E
A
K
S
H
A
P
E
M. Rapala, IRFU/DPhN/LERN
Page 66
May 30, 2017
•
Triple Gaussian + Compton tails
•
Peak shape
•
Not a simple Gaussian
•
Gating with subtracted background
•
Choosing correct background
S
P
E
C
T
R
A
F
I
T
T
I
N
G
P
R
O
B
L
E
M
S
M. Rapala, IRFU/DPhN/LERN
Page 67
May 30, 2017
•
Gating with subtracted background
•
Gate background close to the peak
S
P
E
C
T
R
A
F
I
T
T
I
N
G
P
R
O
B
L
E
M
S
-
B
A
C
K
G
R
O
U
N
D
M. Rapala, IRFU/DPhN/LERN
Page 68
May 30, 2017
401.6keV
Gate 1
Background
•
Gating with subtracted background
•
Gate background close to the peak
S
P
E
C
T
R
A
F
I
T
T
I
N
G
P
R
O
B
L
E
M
S
-
B
A
C
K
G
R
O
U
N
D
M. Rapala, IRFU/DPhN/LERN
Page 69
May 30, 2017
199.2keV
Gate 2
Background
•
Gating with subtracted background
•
Choosing correct background
S
P
E
C
T
R
A
F
I
T
T
I
N
G
P
R
O
B
L
E
M
S
-
B
A
C
K
G
R
O
U
N
D
M. Rapala, IRFU/DPhN/LERN
Page 70
May 30, 2017
•
Gating with subtracted background
•
Choosing correct background
S
P
E
C
T
R
A
F
I
T
T
I
N
G
P
R
O
B
L
E
M
S
-
B
A
C
K
G
R
O
U
N
D
M. Rapala, IRFU/DPhN/LERN
Page 71
May 30, 2017
330.7keV
•
Baseline depends on the placing the background
•
Up to 10% difference depending on the background choice
S
P
E
C
T
R
A
F
I
T
T
I
N
G
P
R
O
B
L
E
M
S
-
B
A
C
K
G
R
O
U
N
D
M. Rapala, IRFU/DPhN/LERN
Page 72
May 30, 2017
330.7keV
A
N
A
L
Y
S
I
S
P
R
O
C
E
D
U
R
E
M. Rapala, IRFU/DPhN/LERN
Page 73
•
Redefinition of background treatment
•
No background subtraction
→ gate scanning needed
May 30, 2017
A
N
A
L
Y
S
I
S
P
R
O
C
E
D
U
R
E
M. Rapala, IRFU/DPhN/LERN
Page 74
May 30, 2017
Horizontal Gates
Vertical Gates
Diagonal Gates
•
Fitted background
•
No contamination
•
N = N
m
- B
H
- B
V
+ B
D
•
Contamination only in
horizontal gate
•
N = N
H
- B
V
+ B
D
D
A
T
A
P
R
E
P
R
O
C
E
S
S
I
N
G
-
T
R
I
P
L
E
-
C
O
I
N
C
I
D
E
N
C
E
M. Rapala, IRFU/DPhN/LERN
Page 75
May 30, 2017
•
Three-dimensional histogram
→
γγγ
-cube
•
Time shift correction for all Ge crystals
•
Energy calibration of all Ge crystals (run after run)
•
Coincidence time window
•
Fixed to 200ns
•
Cube created in Poland at Warsaw University
•
Time needed: 6 to 12 months
D
A
T
A
P
R
E
P
R
O
C
E
S
S
I
N
G
-
T
R
I
P
L
E
-
C
O
I
N
C
I
D
E
N
C
E
M. Rapala, IRFU/DPhN/LERN
Page 76
May 30, 2017
•
Three-dimensional histogram
→
γγγ
-cube
•
Time shift correction for all Ge crystals
•
Energy calibration of all Ge crystals (run after run)
•
Coincidence time window
•
Fixed to 200ns
•
Cube created in Poland at Warsaw University
•
Time needed: 6 to 12 months
•
Dedicated analysis software
•
Choosing gates
•
Fitting spectra in triple-
coincidence
•
No access to the source code
•
Gamma-ray cascade
P
R
E
L
I
M
I
N
A
R
Y
R
E
S
U
L
T
S
M. Rapala, IRFU/DPhN/LERN
Page 77
May 30, 2017
G
a
m
m
a
-
r
a
y
c
a
s
c
a
d
e
i
n
1
4
2
B
a
a
c
c
o
r
d
i
n
g
t
o
E
X
I
L
L
d
a
t
a
G
a
m
m
a
-
r
a
y
c
a
s
c
a
d
e
i
n
1
4
2
B
a
a
c
c
o
r
d
i
n
g
t
o
2
4
8
C
m
d
a
t
a
Urban et al., Nucl. Phys A 613 (1997) 107
T. Materna et al., accepted for publ. In EPJ Web of Conferences (2017)
•
Gamma-ray cascade
•
Transition intensity
values very close
especially in ground
state band
P
R
E
L
I
M
I
N
A
R
Y
R
E
S
U
L
T
S
M. Rapala, IRFU/DPhN/LERN
Page 78
May 30, 2017
•
Gamma-ray cascade
•
Transition intensity
values very close
especially in ground
state band
•
Probably initial spins
of the primary fission
fragments in both
systems are similar
P
R
E
L
I
M
I
N
A
R
Y
R
E
S
U
L
T
S
M. Rapala, IRFU/DPhN/LERN
Page 79
May 30, 2017
P
R
E
L
I
M
I
N
A
R
Y
R
E
S
U
L
T
S
M. Rapala, IRFU/DPhN/LERN
Page 80
May 30, 2017
G
a
m
m
a
-
r
a
y
c
a
s
c
a
d
e
i
n
9
2
K
r
a
c
c
o
r
d
i
n
g
t
o
E
X
I
L
L
d
a
t
a
(in coincidence with
142
Ba)
T. Materna et al., accepted for publ. In EPJ Web of Conferences (2017)
P
R
E
L
I
M
I
N
A
R
Y
R
E
S
U
L
T
S
M. Rapala, IRFU/DPhN/LERN
Page 81
May 30, 2017
G
a
m
m
a
-
r
a
y
c
a
s
c
a
d
e
i
n
9
2
K
r
a
c
c
o
r
d
i
n
g
t
o
E
X
I
L
L
d
a
t
a
(in coincidence with
142
Ba)
G
a
m
m
a
-
r
a
y
c
a
s
c
a
d
e
i
n
9
2
K
r
a
c
c
o
r
d
i
n
g
t
o
F
I
F
R
E
L
I
N
(old RIPL-3 version, without low intensity transitions, in coincidence with
142
Ba)
T. Materna et al., accepted for publ. In EPJ Web of Conferences (2017)
P
R
E
L
I
M
I
N
A
R
Y
R
E
S
U
L
T
S
M. Rapala, IRFU/DPhN/LERN
Page 82
May 30, 2017
G
a
m
m
a
-
r
a
y
c
a
s
c
a
d
e
i
n
9
2
K
r
a
c
c
o
r
d
i
n
g
t
o
E
X
I
L
L
d
a
t
a
(in coincidence with
142
Ba)
G
a
m
m
a
-
r
a
y
c
a
s
c
a
d
e
i
n
9
2
K
r
a
c
c
o
r
d
i
n
g
t
o
F
I
F
R
E
L
I
N
(new RIPL-3 version, without low intensity transitions,
in coincidence with
142
Ba)
•
RIPL-3 update
•
Strong dependence of the
FIFRELIN simulation output on
spin values
T. Materna et al., accepted for publ. In EPJ Web of Conferences (2017)
T. Materna et al., accepted for publ. In EPJ Web of Conferences (2017)
CEA Saclay:
•
Analysis of other fission fragment pairs
•
Comparison to
248
Cm and
252
Cf experimental data
•
Comparison to FIFRELIN simulation results
P
H
D
O
U
T
L
O
O
K
M. Rapala, IRFU/DPhN/LERN
Page 83
May 30, 2017
CEA Saclay:
•
Analysis of other fission fragment pairs
•
Comparison to
248
Cm and
252
Cf experimental data
•
Comparison to FIFRELIN simulation results
CEA Cadarache:
•
Comparison of gathered experimental data results to
FIFRELIN simulation results
•
Evaluation and improvement of the models
implemented in the code
P
H
D
O
U
T
L
O
O
K
M. Rapala, IRFU/DPhN/LERN
Page 84
May 30, 2017
FIPPS experiment
•
At ILL in Grenoble (the same beamline as EXILL)
•
Phase I started operation in January 2017
•
HPGe array – 8 detectors
O
U
T
L
O
O
K
M. Rapala, IRFU/DPhN/LERN
Page 85
May 30, 2017
Institut Laue-Langevin,
https://www.ill.eu/instruments-support/instruments-
groups/instruments/fipps/description/fipps-hpge-array/ (2017)
FIPPS experiment
•
At ILL in Grenoble (the same beamline as EXILL)
•
Phase I started operation in January 2017
•
HPGe array – 8 detectors
O
U
T
L
O
O
K
M. Rapala, IRFU/DPhN/LERN
Page 86
May 30, 2017
•
Plans:
•
Active target (fission trigger)
•
Anti-Compton shield
•
Outcomes:
•
Lower background
•
Less contaminants
•
Better energy resolution
Institut Laue-Langevin,
https://www.ill.eu/instruments-support/instruments-
groups/instruments/fipps/description/fipps-hpge-array/ (2017)
Delve into the nuclear fission process through prompt gamma-ray spectrometry, exploring motivations, experimental data, and preliminary results. Understand the gamma heating process in nuclear reactors and its significance in reactor safety. Contextualize the study within Generation III+ and IV reactors, aiming for higher accuracy and safety through precise simulations and code improvements.
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Study of the nuclear fission process by prompt gamma-ray spectrometry MICHA R PA A PHENIICS Fest, Orsay, 30 May 2017
PRESENTATION OUTLINE Motivations Experimental data EXILL EXPERIMENT Preliminary results BA KR Conclusions M. Rapala, IRFU/DPhN/LERN May 30, 2017 Page 2
Motivations M. Rapala, IRFU/DPhN/LERN May 30, 2017 Page 3
GAMMA HEATING PROCESS IN A NUCLEAR REACTOR Result of gamma-ray energy deposition HTMR Asia Development Limited, http://www.htmr-asia.com/en/product.php?id=27 (2014) M. Rapala, IRFU/DPhN/LERN May 30, 2017 Page 4
GAMMA HEATING PROCESS IN A NUCLEAR REACTOR Result of gamma-ray energy deposition HTMR Asia Development Limited, http://www.htmr-asia.com/en/product.php?id=27 (2014) Areva , UK-EPR, Fundamental safety overview Vol. 1, Chapter A, Page 63 S. Sen et al., Nuclear Engineering and Design Vol. 293, Pages 323-329 (2015) M. Rapala, IRFU/DPhN/LERN May 30, 2017 Page 5
GAMMA HEATING PROCESS IN A NUCLEAR REACTOR Almost 100% of total heating in the reflector A-C. Colombier et al., EPJ Web of Conferences 42, 04001 (2013) M. Rapala, IRFU/DPhN/LERN May 30, 2017 Page 6
CONTEXT OF THE STUDY Generation III+ and IV reactors More accurate simulation Higher safety Gamma heating process More precise simulation M. Rapala, IRFU/DPhN/LERN May 30, 2017 Page 7
CONTEXT OF THE STUDY Generation III+ and IV reactors More accurate simulation Higher safety Gamma heating process More precise simulation Fission fragment deexcitation simulation code Improvement of implemented models Fission Prompt gamma-ray cascade M. Rapala, IRFU/DPhN/LERN May 30, 2017 Page 8
FISSION PROCESS What we want to study: FISSION PROCESS PROMPT GAMMA-RAY CASCADE IN FISSION FRAGMENTS Courtesy of J.F. Lema tre, SPhN, IRFU, DRF, CEA Saclay M. Rapala, IRFU/DPhN/LERN May 30, 2017 Page 9
FISSION FRAGMENT DEEXCITATION The continuum The part partially completed from the models The experimental nuclear levels O. Litaize et al., ND-2016, Bruges M. Rapala, IRFU/DPhN/LERN May 30, 2017 Page 10
PROMPT GAMMA-RAY CASCADE Main questions concerning de-excitation process: What happens after the scission point? How is the excitation energy shared between fragments? the two What distributions? Are they correlated? are the initial spin What generates fragment? is the high process spin that the in M. Rapala, IRFU/DPhN/LERN May 30, 2017 Page 11
FIFRELIN MONTE-CARLO SIMULATION CODE Simulates fission fragments de-excitation Observables M. Rapala, IRFU/DPhN/LERN May 30, 2017 Page 12
Experimental data M. Rapala, IRFU/DPhN/LERN May 30, 2017 Page 13
EXOGAM EXPERIMENT AT ILL - EXILL Array of Ge-detectors around a fissile target in a intense cold neutron beam 15 DAYS WITH235U (575 G/CM2) + SN/ZR 5 DAYS WITH235U (675 G/CM2) + BE 15 DAYS WITH241PU (300 G/CM2) + BE 8 EXOGAM clovers + 2 ILL clovers + 6 GASP Ge + BGO shielding WITHOUT LABR3DETECTORS Analysis of 235U data M. Rapala, IRFU/DPhN/LERN May 30, 2017 Page 14
DATA ANALYSIS Triple- coincidence Analysis software CHOOSING GATES Selecting fragments fission FITTING TRIPLE- COINCIDENCE SPECTRA IN CALCULATING INTENSITY GAMMA-RAY TRANSITION AND ANTICIPATION THE UNCERTAINTY PROPAGATION RELATIVE OF THE OF M. Rapala, IRFU/DPhN/LERN May 30, 2017 Page 15
Triple- coincidence in practice M. Rapala, IRFU/DPhN/LERN May 30, 2017 Page 16
RAW DATA M. Rapala, IRFU/DPhN/LERN May 30, 2017 Page 17
GATES SELECTION 92Kr 142Ba Rz ca-Urban et al., Eur. Phys. J. A 9 (2000) 165 Urban et al., Nucl. Phys A 613 (1997) 107 M. Rapala, IRFU/DPhN/LERN May 30, 2017 Page 18
GATES SELECTION 92Kr 142Ba Rz ca-Urban et al., Eur. Phys. J. A 9 (2000) 165 Urban et al., Nucl. Phys A 613 (1997) 107 M. Rapala, IRFU/DPhN/LERN May 30, 2017 Page 19
SIMPLE COINCIDENCE OUTCOME Cleaner spectrum STILL HIGH BACKGROUND AND MANY CONTAMINANTS 769.0keV M. Rapala, IRFU/DPhN/LERN May 30, 2017 Page 20
TRIPLE- COINCIDENCE OUTCOME Clean spectrum REDUCED BACKGROUND CLEARLY VISIBLE PEAKS 359.5keV 769.0keV M. Rapala, IRFU/DPhN/LERN May 30, 2017 Page 21
PEAK IDENTIFICATION 92Kr 142Ba M. Rapala, IRFU/DPhN/LERN May 30, 2017 Page 22
Preliminary Results M. Rapala, IRFU/DPhN/LERN May 30, 2017 Page 23
PRELIMINARY RESULTS Gamma-ray cascade Gamma-ray cascade in 142Ba according to FIFRELIN T. Materna et al., accepted for publ. In EPJ Web of Conferences (2017) M. Rapala, IRFU/DPhN/LERN May 30, 2017 Page 24
PRELIMINARY RESULTS Gamma-ray cascade Gamma-ray cascade in 142Ba according to FIFRELIN T. Materna et al., accepted for publ. In EPJ Web of Conferences (2017) Gamma-ray cascade in 142Ba according to EXILL data T. Materna et al., accepted for publ. In EPJ Web of Conferences (2017) M. Rapala, IRFU/DPhN/LERN May 30, 2017 Page 25
PRELIMINARY RESULTS Gamma-ray cascade I E (keV) J1 J2 EXILL* FIFR.** Ratio(**/*) 1.00 (3) 359.6 2+ 0+ 100 (3) 100.0 (1) 475.2 4+ 2+ 80 (2) 91.4 (2) 1.14 (3) 631.2 6+ 4+ 42 (2) 66.3 (1) 1.58 (8) 693.4 8+ 6+ 12 (1) 26.0 (1) 2.2 (2) 766.5 10+ 8+ 2.4 (7) 3.60 (3) 1.5 (4) 706.8 5- 4+ 10 (1) 10.17 (5) 1.0 (1) 486.7 7- 6+ 8 (1) 15.60 (6) 1.9 (2) 354.4 9- 8+ 4.4 (5) 8.40 (4) 1.9 (2) 561.1 9- 7- 4.0 (5) 7.52 (4) 1.9 (2) 640.1 11- 9- 2 (1) 6.22 (3) 3 (2) 380.9 8+ 6+ 4.0 (6) 5.06 (3) 1.3 (2) 585.6 10+ 8+ 4 (1) 5.66 (3) 1.4 (4) Gamma-ray cascade in 142Ba according to FIFRELIN T. Materna et al., accepted for publ. In EPJ Web of Conferences (2017) M. Rapala, IRFU/DPhN/LERN May 30, 2017 Page 26
PRELIMINARY RESULTS Gamma-ray cascade GOOD AGREEMENT LOW SPIN TRANSITIONS FOR I E (keV) J1 J2 EXILL* FIFR.** Ratio(**/*) 1.00 (3) 359.6 2+ 0+ 100 (3) 100.0 (1) HIGH OVERESTIMATED FIFRELIN CODE SPIN TRANSITIONS 475.2 4+ 2+ 80 (2) 91.4 (2) 1.14 (3) BY 631.2 6+ 4+ 42 (2) 66.3 (1) 1.58 (8) 693.4 8+ 6+ 12 (1) 26.0 (1) 2.2 (2) 766.5 10+ 8+ 2.4 (7) 3.60 (3) 1.5 (4) 706.8 5- 4+ 10 (1) 10.17 (5) 1.0 (1) 486.7 7- 6+ 8 (1) 15.60 (6) 1.9 (2) 354.4 9- 8+ 4.4 (5) 8.40 (4) 1.9 (2) 561.1 9- 7- 4.0 (5) 7.52 (4) 1.9 (2) 640.1 11- 9- 2 (1) 6.22 (3) 3 (2) 380.9 8+ 6+ 4.0 (6) 5.06 (3) 1.3 (2) 585.6 10+ 8+ 4 (1) 5.66 (3) 1.4 (4) M. Rapala, IRFU/DPhN/LERN May 30, 2017 Page 27
PRELIMINARY RESULTS Gamma-ray cascade GOOD AGREEMENT LOW SPIN TRANSITIONS FOR I E (keV) J1 J2 EXILL* FIFR.** Ratio(**/*) 1.00 (3) 359.6 2+ 0+ 100 (3) 100.0 (1) HIGH OVERESTIMATED FIFRELIN CODE SPIN TRANSITIONS 475.2 4+ 2+ 80 (2) 91.4 (2) 1.14 (3) BY 631.2 6+ 4+ 42 (2) 66.3 (1) 1.58 (8) 693.4 8+ 6+ 12 (1) 26.0 (1) 2.2 (2) 766.5 10+ 8+ 2.4 (7) 3.60 (3) 1.5 (4) PROBABLY ESTIMATION VALUE FRAGMENT DISTRIBUTION WRONG A MEAN FISSION SPIN 706.8 5- 4+ 10 (1) 10.17 (5) 1.0 (1) OF THE 486.7 7- 6+ 8 (1) 15.60 (6) 1.9 (2) OF 354.4 9- 8+ 4.4 (5) 8.40 (4) 1.9 (2) 561.1 9- 7- 4.0 (5) 7.52 (4) 1.9 (2) 640.1 11- 9- 2 (1) 6.22 (3) 3 (2) 380.9 8+ 6+ 4.0 (6) 5.06 (3) 1.3 (2) 585.6 10+ 8+ 4 (1) 5.66 (3) 1.4 (4) M. Rapala, IRFU/DPhN/LERN May 30, 2017 Page 28
PRELIMINARY RESULTS Dependence on a complementary fragment (neutron evaporation) 61+ 4+ 81+ 61+ 7- 61+ 5- 4+ FIFRELIN simulated transition intensities in 142Ba M. Rapala, IRFU/DPhN/LERN May 30, 2017 Page 29
PRELIMINARY RESULTS Dependence on a complementary fragment (neutron evaporation) 61+ 4+ 61+ 4+ 5- 4+ 81+ 61+ 81+ 61+ 7- 61+ 5- 4+ 7- 61+ EXILL data transition intensities in 142Ba FIFRELIN simulated transition intensities in 142Ba M. Rapala, IRFU/DPhN/LERN May 30, 2017 Page 30
PRELIMINARY RESULTS 4 neutrons In FIFRELIN initial spin is constant 3 neutrons Eex [MeV] 2 neutrons 1 neutron 0 neutrons J [ ] M. Rapala, IRFU/DPhN/LERN May 30, 2017 Page 31
PRELIMINARY RESULTS 4 neutrons In FIFRELIN initial spin is constant 3 neutrons Neutron evaporation follows the mean value of the level density distribution Eex [MeV] 2 neutrons 1 neutron 0 neutrons J [ ] M. Rapala, IRFU/DPhN/LERN May 30, 2017 Page 32
PRELIMINARY RESULTS 4 neutrons In FIFRELIN initial spin is constant 3 neutrons Neutron evaporation follows the mean value of the level density distribution Eex [MeV] 2 neutrons With neutrons transitions are produced more evaporated high 1 neutron less spin 0 neutrons J [ ] M. Rapala, IRFU/DPhN/LERN May 30, 2017 Page 33
Conclusions M. Rapala, IRFU/DPhN/LERN May 30, 2017 Page 34
CONCLUSIONS Systematic study of the prompt gamma-ray cascades of the fission fragments TRIPLE- COINCIDENCE TECHNIQUE ANALYSIS MADE ON A FEW (THE MOST ABUNDANT) FISSION FRAGMENT PAIRS RESULTS WILL HELP TO IMPROVE SIMULATIONS OF GAMMA HEATING IN NUCLEAR REACTORS Benchmarking the MC simulation code FIFRELIN COMPARISON TO FIFRELIN SIMULATION RESULTS SOME EFFECTS NEED FURTHER INVESTIGATION M. Rapala, IRFU/DPhN/LERN May 30, 2017 Page 35
COLLABORATION T. Materna1, A. Letourneau1, A. Marchix1, O. Litaize2, O. S rot2, D. Regnier2, W. Urban3, A. Blanc4, M. Jentschel4, U. K ster4, P. Mutti4, T. Soldner4, G. Simpson5, C lin A. Ur6, and G. de France7 1 Irfu, Universit Paris-Saclay, Gif-sur-Yvette, France 2 CEA, DEN, DER, Cadarache, Saint-Paul-lez-Durance, France 3 Faculty of Physics, University of Warsaw, Warsaw, Poland 4 Institut Laue-Langevin, Grenoble, France 5 LPSC, CNRS/IN2P3, Grenoble, France 6INFN, Legnaro, Italy 7 GANIL, Caen, France M. Rapala, IRFU/DPhN/LERN May 30, 2017 Page 36
PHD AIMS CEA Saclay DATA ANALYSIS TECHNIQUE DEVELOPMENT DATA ANALYSIS GATHERING INFORMATION ABOUT GAMMA-RAY CASCADE COMPARING EXPERIMENTAL DATA WITH SIMULATION RESULTS CEA Cadarache COMPARING EXPERIMENTAL DATA WITH SIMULATION RESULTS TESTING DIFFERENT PARAMETER SETUPS IMPROVING SIMULATION CODE M. Rapala, IRFU/DPhN/LERN May 30, 2017 Page 38
FITTING PROBLEMS Too high uncertainty TOO HIGH STATISTICAL ERROR Peak shape too complicated PROBLEMS WITH DETECTORS ENERGY RESOLUTION AND TAILS OUR PEAK LOOKS LIKE TRIPLE GAUSSIAN + COMPTON ADDITIONAL PEAKS NEEDED TO REPRODUCE THE CORRECT SHAPE Wrong volume of the peaks CONTAMINANTS INCLUDED IN THE GATES M. Rapala, IRFU/DPhN/LERN May 30, 2017 Page 39
DETECTION SYSTEM CALIBRATION Europium source data used for calibration 152Eu 152Gd or 152Sm Three types of detectors with different performance M. Rapala, IRFU/DPhN/LERN May 30, 2017 Page 40
DETECTION SYSTEM CALIBRATION Europium source data used for calibration 152Eu 152Gd or 152Sm Three types of detectors with different performance Total coincidence efficiency formula simplification M. Rapala, IRFU/DPhN/LERN May 30, 2017 Page 41
DETECTION SYSTEM CALIBRATION Europium source data used for calibration 152Eu 152Gd or 152Sm Three types of detectors with different performance Total coincidence efficiency formula simplification M. Rapala, IRFU/DPhN/LERN May 30, 2017 Page 42
DETECTION SYSTEM CALIBRATION Europium source data used for calibration 152Eu 152Gd or 152Sm Three types of detectors with different performance Total coincidence efficiency formula simplification DIFFERENCE LOWER THAN 2% IN RANGE BETWEEN 100KEV TO 1.5MEV M. Rapala, IRFU/DPhN/LERN May 30, 2017 Page 43
DETECTION SYSTEM CALIBRATION Europium source data used for calibration 152Eu 152Gd or 152Sm Three types of detectors with different performance Total coincidence efficiency formula simplification Correction of true coincidence effect Efficiency [%] Efficiency [%] Energy [keV] Energy [keV] M. Rapala, IRFU/DPhN/LERN May 30, 2017 Page 44
EXILL RESOLUTION 91Zr(n, ) 92ZR PEAK AT 1405 KEV FWHM EQUAL TO 3.7 KEV CHI2/NDF EQUAL TO 1.7 M. Rapala, IRFU/DPhN/LERN May 30, 2017 Page 45
SPECTRA FITTING PROBLEMS Peak shape NOT A SIMPLE GAUSSIAN Gating with subtracted background CHOOSING CORRECT BACKGROUND Peak/Background ratio GATES WIDTH Contaminants in the gates GATES WIDTH M. Rapala, IRFU/DPhN/LERN May 30, 2017 Page 46
SPECTRA FITTING PROBLEMS - PEAK/BACKGROUND Better value of the peak/background ratio 2 bins gate width 1 bin gate width M. Rapala, IRFU/DPhN/LERN May 30, 2017 Page 47
SPECTRA FITTING PROBLEMS - CONTAMINATION Better visibility of contaminants More precise contamination positioning More precise results Lower uncertainty 2 bins gate width 1 bin gate width M. Rapala, IRFU/DPhN/LERN May 30, 2017 Page 48
PRELIMINARY RESULTS Dependence on a complementary fragment (neutron evaporation) EFFECT CAUSED BY DEPENDENCE BETWEEN EXCITATION ENERGY AND LEVEL DENSITY 61+ 4+ 81+ 61+ 7- 61+ 5- 4+ FIFRELIN simulated transition intensities in 142Ba M. Rapala, IRFU/DPhN/LERN May 30, 2017 Page 49
PRELIMINARY RESULTS Dependence on a complementary fragment (neutron evaporation) EFFECT CAUSED BY DEPENDENCE BETWEEN EXCITATION ENERGY AND LEVEL DENSITY 61+ 4+ MORE EVAPORATED NEUTRONS 81+ 61+ LOWER EXCITATION ENERGY OF THE FISSION FRAGMENTS AFTER NEUTRON EVAPORATION 7- 61+ 5- 4+ FIFRELIN simulated transition intensities in 142Ba LOWER PROBABILITY OF HIGH-SPIN TRANSITION PRODUCTION M. Rapala, IRFU/DPhN/LERN May 30, 2017 Page 50
