The FLUKA Monte Carlo code

Transcription

1 The FLUKA Monte Carlo code Mattias Lantz Applied Nuclear Physics Department of Physics & Astronomy Uppsala University This introduction to the FLUKA MC is part of the course Modelling and simulation methods of particle transport, 5 credits, 1FA451

2 OUTLINE Part 1: What is FLUKA? History Code design and features Physics Applications Nice new tools Part 2: Practical hints Part 3: Exercises

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4 History of FLUKA 1962: MC code(s) for high-energy proton beams J. Ranft (Leipzig) and H. Geibel (CERN) Histor y of FLUK A 1970: Study of event-by-event fluctuations in calorimeters => FLUktuierende KAskade Mainly used for radiation shielding studies : Development by J. Ranft and J.H. Möhring (Leipzig) with significant contributions from P. Aarnio and J. Routti (Helsinki), J.M. Zazula (Cracow) and A. Fassò and G.R. Stephenson (CERN) 1989-: A. Ferrari and P.R. Sala (INFN Milano), together with A. Fassò and J. Ranft, transforms FLUKA into a general purpose MC code 2003: CERN-INFN Collaboration Agreement 2006: Many improvements, free format input, nice tools 2011: Gfortran option available

5 History of FLUKA BEAM nrc GEANT LAHET FLUKA HETC EGS MARS PHITS PENELOPE MCNP/MCNPX SHIELD-HIT MORSE Funny comparison between FLUKA, GEANT, and SHIELD-HIT:

6 History of FLUKA Comparison of number of publications between different MC codes

7 F l u k a FLUKA is: i s A stand-alone Monte Carlo code for transport and interaction of particles and nuclei with matter Hadron-hadron and hadron-nucleus interactions: 1 kev TeV Nucleus-nucleus interactions: ~10 of MeV/A TeV/A (1) E.m. and μ interactions: 1 kev TeV Neutron multi-group transport and interactions: thermal 20 MeV (2) Photo-nuclear interactions Optical photon generation and interactions (Cherenkov, scintillation,...) Neutrino generation and interactions Charged particle transport including all relevant processes Residual nuclei calculations, time evolution, residual dose calculations,... Combinatorial geometry with optional voxel and lattice capabilities Interface to GEANT4 geometry package, AutoCAD, SimpleGeo,... Analog calculations or with variance reduction Precision transport in magnetic fields (1) Can not handle D, T, He-3, He4 yet (2): recently extended from 72 to more than 260 groups. Point-like cross sections for a few selected nuclei

8 Code design and features Sound and modern physics: Based, as far as possible, on original and well-tested microscopic models All steps should be self-consistent and with solid physical basis Optimized by comparing with experimental data at single interaction level No tuning on integral data such as thick target yields, etc. Final predictions obtained with a minimum of free parameters which are fixed for all energies, targets and projectiles Basic conservation laws are fulfilled a priori Correlations are fully preserved within interactions and among showers components The physical models of FLUKA are fully integrated, with full cross-talk between all components (FLUKA is NOT a toolkit! Compare with GEANT) Results from complex cases arise naturally from the underlying physical models Suitable environment for exotic extensions (ν, N-decay ) Predictivity where no experimental data are directly available

9 Code design and features High accuracy: Systematic use of relativistic kinematics All variables are double precision Tabulated total cross sections and other integral nuclear and atomic data are used (slower, but gives better accuracy than parametrizations) Differential cross sections obtained by sampling reaction channels and energies by physical models Effort to use accurate mathematical and physical algorithms in order to achieve the same level of accuracy for each component and at all energies FORTRAN-77 code: The code has about 500,000 lines of code (~17 MBytes) Internal memory management, dynamical memory allocation Available on Linux x86 (g77), Compac TrueUnix and Mac OSX (g95),... Also KNOPPIX version (FLUPIX), bootable from any host OS Also used in mixed-language applications, for instance C++ with GEANT4 geometry package (FLUGG interface)

10 Code design and features No programming required for standard cases: All scoring, cutoff settings, biasing, etc. are defined by the user without any need to write code This allows very optimized scoring algorithms Difficult to convince users that are accustomed to other codes Very powerful user routines are available for special cases where the standard scoring is not enough for the user or when complex input kinematics is necessary Scoring: Event-by-event Coincident/Anti-coincident Time gates Angle dependence w.r.t. surfaces Fluctuations and correlations... (~10 more) Many different biasing options (~10) can be activated

11 Physics Hadronic models in FLUKA

12 Physics: thin target example Angle-integrated 90Zr(p,xn) at 80.5 MeV The various lines show contributions from: evaporation INC pre-equilibrium total Experimental data: M. Trabandt et al., Phys. Rev. C39, 452 (1989)

13 Physics: thick target example Neutron double-differential distributions from protons on stopping-length targets Exp. data: Meier et al., Nucl. Sci. Eng. 110, 299 (1992) and Meigo et al., JAERI-Conf

14 Physics: modified RQMD Double-differential neutron yield by 400 MeV/n Ar and Fe ions on thick Al targets Experimental data points: Phys. Rev. C62, (2000)

15 Applications Energy production, waste transmutation: Energy Amplifier LHC: beam-machine interaction and radioprotection LHC/ATLAS/CMS: radiation background in detectors LHC/ATLAS: calorimetry simulation LHC/ALICE: general detector simulation Neutrino beams from accelerators: WANF & CNGS Cosmic rays: calculation of secondary particles in atmosphere ICARUS: general detector and physics simulation BOREXINO: radioactive background studies Dose calculations: civil aviation Dose calculations: space missions Medical physics: hadrotherapy

16 Applications ATLAS: radiation background and calorimetry E. Gschwendtner, C.W. Fabjan, N. Hessey, T. Otto, and H. Vincke, Measuring the radiation background in the ATLAS experiment, Nucl. Instr. Meth. A476, 222 (2002) (benchmarked up to 14 attenuation lengths) Photon background Neutron background

17 Applications LHC: collimation, beam dump effects RF Momentun Cleaning CMS Point 4 Point 5 LHC Dump Point 3.3 Point 3.2 The LHC Loss Regions Point 6 Regions of high losses (e.g., Collimators, ) Point 2 Regions with low losses (e.g., due to residual gas) Point 7 Betatron Cleaning Point 8 ALICE Point 1 LHCb ATLAS

18 Applications Cooling time Residual dose rate (msv/h) after one year of operation 8 hours 1 week 4 months CERN-SC RP-TN

19 Applications LHC: Complex magnetic fields included Cold Dipole Warm Quadrupole

20 Applications Cosmic rays: Physics and dosimetry Atmosphere: 100 layers ( 50 or 200 as options ) Cone amplitude Depending on allowed tolerance On geomagnetic cut-off First 3-D calculation of atmospheric neutrinos was done with FLUKA. Showed unexpected enhancement in the horizontal direction.

21 Applications Dosimetry: Aviation and space missions S. Roesler et al., Rad. Prot. Dos. 98 (2002) 367 Atmospheric neutron fluence above Narita Airport (Tokyo) Ambient dose equivalent from neutrons at solar activity maximum, on commercial flights from Seattle to Hamburg and from Frankfurt to Johannesburg

22 Applications CN GS CNGS: Cern Neutrino beam to Gran Sasso FLUKA has been used for the physics and engineering design of the CNGS The simulation includes all details of beam transport, interaction, structure of target, horn focusing, decay, etc.

23 Applications CNGS: Properties of the neutrino beam Neutrino event spectra at Gran Sasso National Laboratory

24 Applications ICARUS: LAr TPC Large sensitive volume Continuously sensitive Self-triggering 3D views of ionising events with particle identification Also acts as good homogenous calorimeter of very fine granularity FLUKA used for: full detector simulation atmospheric neutrino generation and interactions CNGS beam simulation Interaction of solar and supernova neutrinos Generation and detection of proton decay Calculation of underground muon events The two 300-ton ICARUS modules inside Laboratori Nazionali di Gran Sasso, Italy

25 Applications ICARUS: Cosmic ray events Transport model: FLUKA (all processes switched on but no production of secondaries) GS geometry: (as taken from the map used in the MACRO experiment) Input: output event by event from atmospheric shower generation Output: event by event, the muons survived at the depth of underground GS lab: 963 m below the surface The geometry of the mountain has been described using the voxel system of FLUKA. Here: 1 voxel = 100 x 100 x 50 m3

26 Applications ICARUS: Cosmic ray events 176 cm Shower Hadronic interaction 434 cm FLUKA simulation

27 Applications Medical applications 12C ions (400 MeV/u) in Water Exp. Data: Haettner et al, Rad. Prot. Dos. 122 (2006) 485 Simulation: A. Mairani, PhD Thesis, Pavia, 2007

28 Applications Medical applications FLUKA can embed voxel structures within its standard combinatorial geometry Optimized transport through the voxels Raw CT-scan outputs can be imported Treatment Planning mgy FLUKA simulation K. Parodi et al, JPCS 74, 2007 mgy

29 Tools TITLE 60.4 MeV proton on Natural Beryllium target assembly * DEFAULTS EET/TRAN BEAM PROTON * BEAMPOS DISCARD EMF PHOTONUC * GEOBEGIN COMBINAT Beryllium Target * Bodies * **AAA*IIII SPH SPH * 5 infinite circular cylinders ZCC ZCC ZCC ZCC ZCC * Infinite planes dividing the cylinders * Planes at an angle for the copper/water cooling spiral PLA PLA * SPH * USRBDX detector planes at 190 cm and 195 cm RPP * Precollimator * Cylinder to construct the upper bump in precollimator ZCC * Truncated cone TRC * Air 017 * Air 018 * Air 019 * Air 020 below water phantom in neutron trap above large paraffin blocks OR OR on outside of large paraffin blocks OR OR OR OR OR OR OR OR OR OR OR OR OR OR OR OR OR OR OR OR OR OR OR OR *_AAAIIIIIAAIIIIIAAIIIIIAAIIIIIAAIIIIIAAIIIIIAAIIIIIAAIIIIIAAIIIIIAAIIIII * Region Paraffine OR OR OR OR OR +62OR +63OR +64OR +65 * Air inbetween large paraffin blocks 026 OR END GEOEND * *GEOEND DEBUG *GEOEND & BIASING BIASING BIASING * HYDROGEN BERYLLIU CARBON OXYGEN MAGNESIU ALUMINUM IRON COPPER COBALT

30 Tools: flair TITLE 60.4 MeV proton on Natural Beryllium target assembly * DEFAULTS EET/TRAN BEAM PROTON * BEAMPOS DISCARD EMF PHOTONUC * GEOBEGIN COMBINAT Beryllium Target * Bodies * **AAA*IIII SPH SPH * 5 infinite circular cylinders ZCC ZCC ZCC ZCC ZCC * Infinite planes dividing the cylinders * Planes at an angle for the copper/water cooling spiral PLA PLA * SPH * USRBDX detector planes at 190 cm and 195 cm RPP * Precollimator * Cylinder to construct the upper bump in precollimator ZCC * Truncated cone TRC * Air 017 * Air 018 * Air 019 * Air 020 below water phantom in neutron trap above large paraffin blocks OR OR on outside of large paraffin blocks OR OR OR OR OR OR OR OR OR OR OR OR OR OR OR OR OR OR OR OR OR OR OR OR *_AAAIIIIIAAIIIIIAAIIIIIAAIIIIIAAIIIIIAAIIIIIAAIIIIIAAIIIIIAAIIIIIAAIIIII * Region Paraffine OR OR OR OR OR +62OR +63OR +64OR +65 * Air inbetween large paraffin blocks 026 OR END GEOEND * *GEOEND DEBUG *GEOEND & BIASING BIASING BIASING * HYDROGEN BERYLLIU CARBON OXYGEN MAGNESIU ALUMINUM IRON COPPER COBALT

31 Tools Old way: 2-dimensional cuts for debugging and visualization of energy deposition, fluence, dose rate, etc... (still nice, but...) File: lacassagne.inp

32 Tools: flair File: lacassagne.inp

33 Tools: SimpleGeo File: lacassagne.inp

34 Part 2: Use existing course material Go to the FLUKA web site Click on Courses and select the 11th FLUKA Course (Prague) Click on Program

35 Some of the downloadable pdfs are also available on Studentportalen