A nton ín Krása, Mitja Majerle for the Energy plus Transmutation collaboration
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Transcript of A nton ín Krása, Mitja Majerle for the Energy plus Transmutation collaboration
Antonín Krása, Mitja Majerle
for the Energy plus Transmutation Energy plus Transmutation collaboration
Neutron Production in Spallation Neutron Production in Spallation Reactions Reactions
ofof p+Pb, d+Pb at p+Pb, d+Pb at GeV EnergiesGeV Energies(Experiment versus Monte Carlo simula(Experiment versus Monte Carlo simulationtion))
OutlineOutline
• Motivation • Performed experiments• Energy + Transmutation setup• Monte-Carlo simulations• Neutron spectra
• Low-energy region (activation foils)• Intermediate region (activation foils)• High-energy region (SSNTD)
• Sources of differences experiment × simulations
Motivation and Motivation and TTasksasks
• Experimental data for testing the codes for simulation of neutron production and transport in ADT systems
• Measurement of neutron field produced in irradiation of:
• thick target,
• thick target + moderator,
• thick target + fissionable blanket + moderator
with relativistic protons and deuterons
• Comparison: experimental × Monte-Carlo simulations check accuracy of nuclear models and x-section libraries
Experiments onExperiments on thick target (+ thick target (+ moderator)moderator)
.
Beam energy [GeV]
YearIrradiation time [h:m]
Integral beam flux
[1013]Setup Accelerator
1.5 1998 8:35 8.9Pb target
Synchro-phasotron
W target
0.885 1999 2:03 3.46Pb target + moderator
1.3 2000 3:17 2.77
Pb target2.5 2000 2:02 4.07
0.66 2003 0:10 158 Pb target Phasotron
Phasotron setup 660 MeVPhasotron setup 660 MeV
Synchrophasotron setup 885 MeVSynchrophasotron setup 885 MeV
Beam energy [GeV]
Beam particles
YearIrradiation time [h:m]
Integral beam flux
[1013]Set-up Accelerator
0.7
protons
2004 8:51 1.47
Pb-target
+
U-blanket
+
(CH2)n-
moderator
Nuclotron
1.0 2003 6:03 3.26
1.5 2001 12:03 1.14
2.0 2003 7:43 1.25
2.52
deuterons
2005 8:00 0.64
1.6 2006 6:46
ExperimentExperimentss onon Energ Energyy+Transmuta+Transmutation tion setupsetup
ENERGY ENERGY ++ TRANSMUTATION setup TRANSMUTATION setup
• target: Pb (28.66 kg) • blanket: U (206.4 kg)• shielding: Cd + (CH2)n
Measurement of Measurement of activated foilsactivated foils
TypeEnergy resolution (FWHM of 60Co at
1332keV)
Relative efficiency
Amplifier ADC
ORTECcoaxial
GR-1819-7600SL
1.90 keV 28.3 %CANBERRA
2026
ORTEC 919 SPECTRUM
MASTER
• High Purity Germanium -spectrometer
Spatial Spatial distributions of distributions of
yields in yields in Al- and Au-foilsAl- and Au-foils
• Example of yields at 1.5 GeV proton
irradiation of E+T setup
Monte-Carlo simulationsMonte-Carlo simulations
Description of U/Pb assembly in MCNPX
• MCNPX 2.6.C• FLUKA
Produced neutron spectrum
• Spallation produces neutrons with keV-GeV energies
• (n,)-reaction covers neutrons with energies up to MeV
1E-8
1E-7
1E-6
1E-5
1E-4
1E-3
1E-2
1E-1
1E-10 1E-8 1E-6 1E-4 1E-2 1E+0 1E+2 1E+4
Energy [MeV]
Nn
eu
tro
ns [
cm-2
pro
ton
-1] target-blanket
tb+box+Cd
1E-5
1E-3
1E-1
1E+1
1E+3
1E+5
1E-10 1E-8 1E-6 1E-4 1E-2 1E+0 1E+2 1E+4
Neutron energy [MeV]
XS
[b
arn
s]
n,gamma
n,xn
n,fission
n,g n,x n n,f
1E-5
1E-3
1E-1
1E+1
1E+3
1E+5
1E-10 1E-8 1E-6 1E-4 1E-2 1E+0 1E+2 1E+4
Neutron energy [MeV]
XS
[b
arn
s]
n,gamma
n,xn
n,fission
n,g n,x n n,f
Activation detectors
SSNTD
Detectors
• Activation detectors :– 197Au(n,xn)197-x+1Au– Bi, Al, Co, Ta, In– Gamma spectrometry
• Solid State Nuclear Track Detectors :– natPb, natU, 235U + mica foils where fission
fragments leave their tracks– Optical microscopy
Results – Phasotron experiment660 MeV, bare, lead target
0
0.5
1
1.5
2
2.5
3
3.5
4
0 10 20 30 40 50
Distance along the target [cm]
Rat
io e
xp/s
im Au-198Au-196Au-194Na-24
1E-08
1E-07
1E-06
1E-05
1E-04
0 10 20 30 40 50
Distance along the target [cm]
B [g
-1 pr
oton
-1]
Au-198
Au-196
Au-194
Na-24
Experiment Experiment/simulation
Energy Plus Transmutation
• Au detectors– Longitudinal– Radial in the first gap
• SSNTD– Radial in all gaps
Results – EPT, 1 GeV protons
0
1
2
3
4
5
0 5 10 15
Radial distance [cm]
Bex
p/B
sim Au-196
Au-194Au-193Au-192
Results – EPT, 1.5 GeV protons
0
1
2
3
4
5
0 5 10 15
Radial distance [cm]
Bex
p/B
sim
Au-196Au-194Au-193Au-192Au-191
Discrepancies
• Disagreement – 1.5 GeV– 2 GeV bigger– 2.52 GeV deuterons – zero ?!
• Only in radial direction• Only for threshold detectors, SSNTD are ok• Causes :
– Experimental error – Simulations
Experimental error ?
• Systematic uncertainties were studied carefully with sets of MCNPX simulations, they are limited to ca. 30% (foil displacement, beam determination)
• Transport of activated material out of foil is below 5%
• Spectrometry – 5%
• … ?
Simulation errors ?• Spallation :
– INC (E>160 MeV), – pre-equilibrium (160MeV>E>40MeV), – evaporation(40 MeV>E).
• Transport of HE neutrons in uranium blanket• More tests:
– Analysis of Yurevich experiments (angular spallation neutron distribution, Ep>1.5 GeV)
– EPT experiment without blanket at 1.5 GeV or 2 GeV– Repeat 1 experiment (1.5 GeV or 2 GeV)