fluka as a new high energy cosmic ray generator g. battistoni 2, a. margiotta 1, s. muraro 2, m....
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FLUKA as a new high energy cosmic ray generator
G. Battistoni2, A. Margiotta1, S. Muraro2, M. Sioli1
University and INFN of 1) Bologna and 2) Milano
for the FLUKA Collaboration
Very Large Volume Telescope Workshop 2009, Athens
Outline
Main features of FLUKA Motivations Code structure Geometry setup First results Conclusions
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FLUKA - Interaction and Transport Monte Carlo code
FLUKA is a general purpose tool for calculations of particle transport and interactions with matter, covering an extended range of applications (Shielding, Radiobiology, High energy physics, Cosmic Ray physics, Nuclear and reactor physics).
Built and maintained with the aim of including the best possible physical models in terms of completeness and precision.
Continuously benchmarked with a wide set of experimental data from well controlled accelerator experiments.
More than 2000 users all over the world Physics models (e.g. hadronic interaction models) built according to a
theoretical microscopic point of view (no parameterizations) => High predictivity also in regions where experimental data are not available
Cosmic Ray physics with FLUKA “triggered” by: HEP physics (e.g. atmospheric neutrino flux calculations) radioprotection in space
FLUKA authors: A. Fasso1, A. Ferrari2, J. Ranft3, P.R. Sala4
1 SLAC Stanford, 2 CERN, 3 Siegen University, 4 INFN Milan http://www.fluka.org
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Motivations extension of the existing FLUKA cosmic-ray library
to high energy region (primaries at the knee of the spectrum) use in underground and underwater sites
use of a unique framework with high quality physics models (FLUKA) for the whole simulation, from primary interaction in the upper atmosphere to the detector level (and through the detector itself, in principle)
creation of a prediction data set (muons and muon-related secondaries) for some topic sites: presently LNGS, ANTARES and Capo Passero sites
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Code structure Geometry description Generation of the kinematics (i.e. the source particles) ↔ primary cosmic ray
composition model 2 hadronic interaction models can be used:
DPMJET-II.53 FLUKA
Output file on an event by event basis – interface between standard and user output (presently ASCII “ANTARES-like” and root output) information on primary cosmic ray generating the shower for each particle reaching the detector level, stores all the relevant parameters (particle ID,
3-momenta, vertex coordinates, momentum in atmosphere, information on the parent mesons etc)
N.B. With FLUKA, shower generation, transport in the sea/rock, and particle folding in the detector is performed inside the same framework
Geometry setup (e.g. LNGS site) 100 atmospheric shells 1 spherical body for the mountain, whose radius is
dynamically changed, according to primary direction and to the Gran Sasso mountain map (direction rock depth)
1 rock box surrounding the experimental underground halls, where muon-induced secondary are activated (e.m. and hadron showers from photo-nuclear interactions)
Underground halls: one box + one semi-cylinder Possibility to include simultaneously more than one
experimental Hall to study large transverse momentum secondaries with detector coincidences)
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Earth
Geometry for underground sites
Spherical mountain whose radius isdynamically changed using a detailedtopographical map
Atmosphere
Primary injection point
z020
22 dcR2RdR
R
d
R0
z
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Geometry setup: LNGS halls
LNGS underground halls
External (rock)volume to propagateall particles down to100 MeV
muon-producedsecondaries
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Some results from the simulation
For a given site (e.g. Hall C at LNGS), possibility to parameterize all particle components reaching the underground level
muons
photons
electrons
log10 Ekin (GeV)
even
ts/y
ear
Vertexes of particles entering the Hall C at LNGS
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Geometry setup (underwater)
Underwater case (e.g. ANTARES/KM3NeT)Earth ≡ sphere of perfectly absorbing mediumsea ≡ spherical shell of wateratmosphere ≡ 100 concentric atmospheric shellsCan ≡ virtual cylindrical surface bounding the
active volume (instrumented volume + 2-3 abs )
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Primary sampling
Primary energy spectrum has the form:
Possibility to choose among different spectra (now MACRO-fit is implemented)
Sampling done re-adapting some HEMAS routines
Aknee
A2
Aknee
A1
EE,EKdEdN
EE,EKdEdN
A2
A1
EEcut
~2.7÷3Ecut~3000 TeV
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Technical issues (biasing)–underwater case■ initialize minimum energy for primary cosmic rays:
lower bound evaluated according to muon survival probabilities 2* Ethr
recompute “on the fly” energy thresholds: muon survival probabilities for various depths in sea water and various
muon energies at surface, evaluated with MUSIC (V. Kudryatsev) muon energy at sea level survival probability < 10-5
function obtained with a fit multiplied by 0.9
underground case : thresholds are evaluated according to the rock map
■ kill in atmosphere all particles with energy lower than this threshold.
■ only muons with E> 20/100 GeV at the can are stored.
■ CPU time request optimized : FULL MC !!!
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Some results from the simulation -1
Vertexes of particles entering a KM3 detector canat 3500 m under sea level
Sea bottom = 3500 m
Can radius = 1000 m height = 1000 m
primaries sampled on a circle with R= 2000 m perpendicular to theirdirection and centered in the origin of the can
muons propagated from the sea level to theirgeometrical intercept withthe detector surface
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Some results from the simulation -2
multiplicity
Log (energy/TeV)
primary energy
multiplicity @ can
meters
muon decoherence
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Conclusions FLUKA can be used as a new high energy cosmic ray generator for
underground and underwater physics. Package developed using LNGS and neutrino telescope sites as examples. It cannot substitute MUPAGE for fast simulation of atmospheric muon
background. Unique framework significant simplification of the FULL MC chain Next steps:
Introduce other primary cosmic ray composition models Extensive studies with FLUKA hadronic model in progress: very encouraging
results! Some space for code optimization. Sea level sampling
Further information: send me an e-mail.
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(ordinary) meson decay: dN/d cos~ 1/ cos
Primary C.R. proton/nucleus: A,E,isotropic
hadronic interaction: multiparticle production (A,E), dN/dx(A,E) extensive air shower
short-lifetime meson production
and prompt decay (e.g. charmed mesons)
Isotropic ang. distr.
detection: N(A,E), dN/dr
transverse size of bundle
Pt(A,E)
(TeV) muon propagation in water : radiative processes and fluctuations
Multi-TeV muon transport
Primary p, He, ..., Fe nuclei with lab. energy from 1 TeV/nucleon up to >10000 TeV/nucleon
The physics of CR TeV muons
The FLUKA hadronic interaction models(for a detailed study of their validity for CR studies :hep-ph/0612075 and 0711.2044)
Hadron-Hadron
Elastic,exchange
Phase shifts
data, eikonal
P<3-5GeV/c
Resonance prod
and decay
low E π,K
Special
High Energy
DPM
hadronization
Hadron-Nucleus Nucleus-Nucleus
E < 5 GeV
PEANUT
Sophisticated GINC
Preequilibrium
Coalescence
High Energy
Glauber-Gribov
multiple interactions
Coarser GINC
Coalescence
E< 0.1GeV/u
BME
Complete fusion+
peripheral
0.1< E< 5 GeV/u
rQMD-2.4
modified
new QMD
E> 5 GeV/u
DPMJET
DPM+
Glauber+
GINC
Evaporation/Fission/Fermi break-up
deexcitation
> 5 GeV Elab
DPM: soft physics based on (multi)Pomeron exchangeDPMJET: soft physics of DPM plus 2+2 processes from pQCD
Relevant forRelevant forHE C.R. physicsHE C.R. physics
22
MINOSMINOS Charge Ratio at the Surface = 1.374 ± 0.004 (stat.) (sys.)
Phys. Rev. D 76, 052003 (2007)
RFLUKA μ+/μ− = 1.333 ± 0.007•Agreement between Agreement between FLUKA simulation and FLUKA simulation and MINOS data within 3%MINOS data within 3%
•Discrepancy Discrepancy systematically remarkablesystematically remarkable
•No dependence on muon No dependence on muon momentum in the momentum in the atmosphere in the range atmosphere in the range consideredconsidered
L3L3 ++ COSMICCOSMIC((hep-ex/0408114).RFLUKA= 1.29 0.05Rexp=1.285 0.003(stat.) ± 0.019(sys.)
012.0010.0