State-of-the-art Shielding Design and
Simulations for Proton, Electron and Ion Beams
Fermilab Accelerator Physics Center
Nikolai Mokhov, Fermilab
International Workshop on FFAGs
Fermilab
September 21-25, 2009
FFAG Workshop, Sep. 21-25, 2009 Shielding Simulations - N. Mokhov2
OUTLINE
• Introduction
• Application Examples & Demands
• General Purpose All-Particle Codes
• Benchmarking (focusing on ion beams)
• Advances in Code Developments
• Recent Proton, Electron and Ion Beam Applications
• Summary
FFAG Workshop, Sep. 21-25, 2009 Shielding Simulations - N. Mokhov3
INTRODUCTION
Requirements to particle transport simulation toolsand needs for physics model and calculation codedevelopments are all driven by application. Themost demanding among them are high-poweraccelerators (Spallation Neutron Source, J-PARC,neutrino factories), heavy-ion and ADS facilities(FRIB, FAIR, EURISOL), high-energy colliders(LHC, ILC), medical beams and space exploration.
Feasibility, design and specific radiation issues areaddressed in detailed Monte-Carlo simulations,therefore, predictive power and reliability ofcorresponding codes are absolutely crucial.
FFAG Workshop, Sep. 21-25, 2009 Shielding Simulations - N. Mokhov4
SNS & Neutrino Factory High-Power Target Buildings
Backscatt
ering
Spectrom
eter
Powder
Diffracto
meter
Magnetis
m &
Liquids
Reflectom
eters
PROTO
NS
SA
NS
Cold
Neutron
Chopper
Spectro
meter
High
Resolution
Chopper
Spectromet
er
Proposed
Spin Echo
Spectrometer
and
Fundamental
Physics
Instruments
To be Built by SNS
Project
To be Built by IDTs
Proposed by IDTs
Areas for
User and
Instrument
Support
FFAG Workshop, Sep. 21-25, 2009 Shielding Simulations - N. Mokhov5
FFAG Workshop, Sep. 21-25, 2009 Shielding Simulations - N. Mokhov6
RIB-factory & Main Injector Collimators
Design optimization via MC calculations:Prompt radiation, residual radiation (hands-onmaintenance), air, ground & sump water activation,beam-induced damage (heating, material integrity,component lifetime), etc.
Marble shells of a brand-newcollimation system at Fermilab MI
Poly mask
FFAG Workshop, Sep. 21-25, 2009 Shielding Simulations - N. Mokhov7
SPACE APPLICATIONS
Space radiation protection is one of five critical enabling technologies identifiedin the NASA Strategic Plan for human space exploration. Issues: knowledge ofgalactic, solar and trapped radiation; astronaut and electronics (SEU!) protection;weight constraints; low-dose biological effects; accuracy of particle andheavy-ion transport physics, etc.
MARS-calculatedcharge transferefficiency degra-dation in CCD:60% at the endof 4-year SNAPmission
FFAG Workshop, Sep. 21-25, 2009 Shielding Simulations - N. Mokhov8
PARTICLE INTERACTION AND TRANSPORT CODES
Only with a very reliable and accuratesimulation code based on modern physicsmodels and data can one perform computermodeling to meet the needs of theapplications described.
Five general-purpose all-particle codes,extensively used worldwide in acceleratorand space applications, are in this category.
FFAG Workshop, Sep. 21-25, 2009 Shielding Simulations - N. Mokhov9
GENERAL PURPOSE ALL-PARTICLE CODES
1. FLUKA* – since 1970, currently FLUKA-2008.3b.1, CERN & INFN
2. GEANT – since 1974, currently GEANT4-9.2, CERN, SLAC et al.
3.MARS* – since 1974, currently MARS15 (2009), FNAL
4.MCNPX – since 1994, originated from earlier MCNP, currently MCNPX-2.6.0, LANL
5. PHITS* – since 2003, currently PHITS-2.15, JAEA, RIST, KEK
Particle energies from hundreds TeV (FLUKA, GEANT, MARS) down to thermal neutron energy, 10-3
FFAG Workshop, Sep. 21-25, 2009 Shielding Simulations - N. Mokhov10
neutrons protons hadrons,..,,, K
nucleusphotons
electrons
JQMD
JAM, Hadron cascade model
In progress
only transport
with dE/dx (SPAR, ATIMA)
200 GeV 200 GeV 200 GeV
100 GeV/u 100 GeV
1 GeV
1 keV
10 MeV/u1 MeV1 MeV
20 MeV
(JQMD)
(Bertini)
(JQMD)
(Bertini)
(JQMD)
thermal 0 MeV 0 MeV 0 MeV/u
GEM, Evaporation process
SPAR, ATIMA, Ionization process
MCNP
with
nuclear data
MCNP
with
nuclear data
EXAMPLE: PHISICS CAPABILITIES IN PHITS
Event Generator
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CODE FEATURES
All five codes can handle very complexgeometries, have powerful user-friendly built-in GUI with magnetic field & tally viewers, andvariance reduction capabilities.
Tallies include volume and surfacedistributions (1D to 3D) of particle flux,energy, reaction rate, energy deposition,residual nuclide inventory, prompt and residualdose equivalent, DPA, event logs, intermediatesource terms, etc.
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Code Multifold Structure: e.g., FLUKA & MARS
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MARS15 EXCLUSIVE EVENT GENERATORS
Improved Cascade-Exciton Model code, CEM03.03,combined with the Fermi break-up model, thecoalescence model, and an improved version of theGeneralized Evaporation-fission Model (GEM2) isused as a default for hadron-nucleus interactionsbelow 3 GeV. Recent multi-fragmentation extension.
The Quark-Gluon String Model code,LAQGSM03.03 (2009), is used in MARS15 forphoton, particle and heavy-ion projectiles at a fewMeV/A to 1 TeV/A. This provides a power of fulltheoretically consistent modeling of exclusive andinclusive distributions of secondary particles,spallation, fission, and fragmentation products.
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Benchmarking: NUCLIDE PRODUCTION
Bremsstrahlung (Emax=1 GeV) on gold 1 GeV/A 86Kr on 9Be
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Neutron Yield from Lead Targets for Heavy-Ion Beams
20x60cm Lead Cylinder
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Accurate Description of Ion dE/dx down to 1 keV
MARS15: fluctuations with correlated energy loss and Coulomb scattering
Example: Ions in Si MARS15 vs data
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500 and 950 MeV/u U-238 on Stainless Steel
MARS15 and PHITS vs GSI data (2007)
Accurate description of HI dE/dx down to keV in mixtures
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Stopped Muons in Uranium: exp vs MARS15
Spectrum of K Muonic X Rays in U-235 and U-238
6000 6100 6200 6300 6400 6500 6600
Energy (keV)
Co
un
ts
U-238
U-235
(A)
Spectrum of L Muonic X Rays in U-235 and U-238
2900 3000 3100 3200 3300 3400
Energy (keV)
Co
un
ts
U-238
U-235
(B)
Experimental data on- cascade in U238 an U235
MARS15
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Technical Drawing Implementation MC Results
geometry
materials
calculated dose isocontours
magne
tic field
LHC MQW quadrupole in FLUKA
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AUTOMATIC GEOMETRY GENERATION
It is a modern approach for acceleratorcomplexes like Tevatron, LHC and J-PARC to builda realistic model of the whole machine for multi-turn beam loss, energy deposition, activation andradiation shielding studies: read in MAD latticeand create a complete geometry and magneticfield model in the framework of such codes asFLUKA, MARS and GEANT.
The experience says that such realistic modelingtakes time and substantial efforts but always paysoff.
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MAD-MARS BEAM LINE BUILDER: J-PARC 3-GeV RING
By N. Nakao
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RECENT BENCHMARKING AT KEK: EP1 LABYRINTH
0 1000 200010-2010-1910-1810-1710-1610-1510-1410-1310-12
Distance from Target (cm)T
otal
Dos
e (m
Sv/
p)
EP1 Labyrinth Experiment500μm Cu Target
Experiment Data neutron+gamma BG correction (On-Off)
MARS15: Total Dose
12GeV-PQ1 Q2
500μm Cu
④ ⑤ ⑥
⑦
Courtesy: Takenori Suzuki
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RECENT BENCHMARKING: 12-GeV K2K TARGET STATION
Courtesy: T. Suzukiand H. Matsumura
1 9
Nine gold foil samplesover 12 meters
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MARS15 Model og J-PARC Labyrinth Tunnel from Switchyard
Access
building
Utility 1
building
Electricity
building
Emergency
tunnel
Utility 2
building
1102 1101
1103
1104
1121
1122
1123
1124
1125
1112
1113
1114
1115
11111031
1032
1033
1034
1035
1036
1037
1038
1039
1045
1044
1043
1042
1041
1046
A
A
B
B
C
C
D DT. Suzuki
13.64 GeV, 5 kW
soil
concrete
Iron
4ft
air
[mSv/h]
1 mrem/h
16.44ft
3ft
12.5ft
3ft
[mrem/h]
10 mrem/h100 mrem/h
0.1 mrem/h
0.01 mrem/h
1 rem/h
67 inch
3ft
70 inch
0.001 mrem/h
0.0001 mrem/h
< 0.5 mrem/h
< 0.1 rem/h
LCLS SHIELDING DESIGN WITH MARS15
Up to 16 GeV e-beam
By T. Sanami
10-2 10-1 100 101 102 103 10410-3
10-2
10-1
100
101
102
103
104
105
Cooling time [day]
Resi
dual
dose
rate
on c
on
tact
[mS
v/h
]
Irradiation time 1day 30day 100day
1hour
1day
1week
1month
1yr
5yr
Tungsten
Copper
13.64GeV 5kW Cu 18X0W3X0W3X0
Beam dump
Beam dump activation
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SHIELDING AND RADIATION EFFECT EXPERIMENT
20 30 40 50 6010-37
10-36
10-35
10-34
10-33
10-32
Product mass number
Mas
s y
ield
s (1
/ato
m/p
roto
n)
Cu
Alcove-1
10 cm
1 m
Target
8 GeV μ+
MARS15 vs data by H. Matsumura
T972 Shielding and RadiationEffect Experiment at FNALJASMIN CollaborationShielding data and code benchmarking;targets, collimators and thick shields;radiation effects on instruments andmaterials. Started in fall 2007.
Example: Muon-induced nuclide production
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Example: FRIB
A brand new project
“Facility for Rare Isotope Beams”
heavily relying on MARS15 and PHITS codes
in target and shielding designs
for up to 400 kW 400 MeV/A uranium beam
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S
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S
FFAG Workshop, Sep. 21-25, 2009 Shielding Simulations - N. Mokhov30
S
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S
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S
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S
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SUMMARY
• Nowadays, there are several Monte-Carlo codes aroundwhich allow to address most of the challenging issues in R&Dand design of radiation shielding, targets, collimators, doseto patients, nuclide production and alike for proton, electronand heavy-ion beams, with impressive results obtained overlast years.
• Results of benchmarking of those widely-used codes arequite encouraging, and in some cases helped reveal existinginconsistencies.
• Some problems/difficulties in the codes are still exist,requiring further developments.
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