a nton ín krása, mitja majerle for the energy plus transmutation collaboration
DESCRIPTION
Neutron Production in Spallation Reactions of p+Pb, d+Pb at GeV Energies (Experiment versus Monte Carlo simula tion ). A nton ín Krása, Mitja Majerle for the Energy plus Transmutation collaboration. Outline. Motivation Performed experiments Energy + Transmutation setup - PowerPoint PPT PresentationTRANSCRIPT
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)