FLUKA as a new high energy cosmic ray generator G. Battistoni, A. Margiotta, S. Muraro, M. Sioli (University and INFN of Bologna and Milano) for the FLUKA Collaboration Blois 2008, Challenges in Particle Astrophysics

M. Sioli, Blois Outline Motivations Main features of FLUKA Code structure The geometry setup  The underground case  The underwater case First results Conclusions

M. Sioli, Blois Motivations Extend the existing FLUKA cosmic-ray library to include the TeV region (primaries at the knee of the spectrum), aimed to underground and underwater sites Different approach with respect to past and present cosmic ray generators: use of a unique framework (FLUKA) for the whole simulation. From 1ry interaction in the upper atmosphere up to the detector level (and the detector itself, in principle) Provide a prediction data set (muons and muon-related secondaries) for some topic sites: presently for LNGS and ANTARES sites Cross check with other dedicated simulation packages (HEMAS, CORSIKA, Cosmos) Cross check with past experimental data (e.g. MACRO)

M. Sioli, Blois Main features of FLUKA FLUKA is a general purpose Monte Carlo code for the interaction and transport of particles in matter in a wide range of energies in user-defined geometries Applications span from shielding design, space physics, calorimetry, dosimetry, medical physics, detector design, particle physics etc. The code is maintained and developed under a CERN-INFN agreement More than 1000 users all over the world Physics models (e.g. hadronic interaction models) are built according to a theoretical microscopic point of view (no parameterizations)  few free parameters, high predictivity but low flexibility Cosmic Ray physics with FLUKA “triggered” by:  HEP physics (e.g. atmospheric neutrino flux calculations)  radioprotection in space FLUKA authors: A. Fasso 1, A. Ferrari 2, J. Ranft 3, P.R. Sala 4 1 SLAC Stanford, 2 CERN, 3 Siegen University, 4 INFN Milan Official web site:

M. Sioli, Blois   (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  P t (A,E) (TeV) muon propagation in the rock: 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 see hep-ph/ and ) 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-NucleusNucleus-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 exchange DPMJET: soft physics of DPM plus 2+2 processes from pQCD Relevant for HE C.R. physics

M. Sioli, Blois Code structure Geometry description Generation of the kinematics (i.e. the source particles) ↔ 1ry cosmic ray composition model Output file on an event by event basis (root tree file):  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 (otherwise different tools have to be patched together)

M. Sioli, Blois 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 2ry 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)

M. Sioli, Blois Earth Geometry for underground sites Spherical mountain whose radius is dynamically changed using a detailed topographical map Atmosphere Primary injection point R d R0R0 z

M. Sioli, Blois Geometry setup: LNGS halls LNGS underground halls External (rock) volume to propagate all particles down to 100 MeV  muon-produced secondaries

M. Sioli, Blois Geometry setup (underwater) Underwater case (e.g. ANTARES)  100 atmospheric shells  Simpler geometrical description (see ≡ concentrical spherical shell of water)  Can ≡ virtual cylindrical surface which set the boundaries for the active volume (instrumented with PM-equipped lines)  Eventually include also here an “active layer” (for secondary production and following)

M. Sioli, Blois Atmosphere Earth Sea Can  Geometry for underwater sites

M. Sioli, Blois Technical issues (biasing)  initialize energy band boundaries for 1ry cosmic rays: lower bound is computed according to muon survival probabilities  recompute “on the fly” energy thresholds: kill particles with E kin <800 GeV at mountain entrance kill particles with E kin <2 GeV inside mountain kill particle with E kin <100 MeV inside rock shell

M. Sioli, Blois Muon and 1ry thresholds In order to bias the deeply falling spectrum, production is divided in 5 energy bins and 6 angular windows Muons with E<E  min have a probability < to survive at h MIN

M. Sioli, Blois Minimum energy/nucleus (TeV) for each mass group, as the function of the angular window Energy/nucleus (TeV) for each mass group, for angular window W 6 Muon and 1ry thresholds

M. Sioli, Blois 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 E E cut  ~2.7 ÷ 3 E cut ~3000 TeV

M. Sioli, Blois 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 E kin (GeV) events/year Vertexes of particles entering in the Hall C at LNGS

M. Sioli, Blois FLUKA and HEMAS-DPM comparison We cross-checked FLUKA with HEMAS-DPM code:  HEMAS was a shower code extensively used in the MACRO collaboration  At the beginning (~1990), HEMAS was the name of both the shower propagation code and of the embedded hadronic interaction model (based on UA1 parameterizations)  this version was used to produce the so-called MACRO-fit 1ry composition model  Later, HEMAS native interaction model was superseeded with DPMJET-II.4 (HEMAS-DPM, Battistoni 1997)  Muon transport in rock treated with another dedicated package (PROPMU, Lipari-Stanev 1991) HEMAS output (only muons) is on an infinite area at underground level  muons have to be sampled on the surface of a box surrounding detector sensitive volumes DIRECT comparison

M. Sioli, Blois FLUKA and HEMAS-DPM comparison HEMAS FLUKA ( MACRO-fit + DPMJET-II.4 ) ( MACRO-fit + DPMJET-II.53 ) Normalized d to the same livetime

M. Sioli, Blois FLUKA and HEMAS-DPM comparison HEMAS FLUKA ( MACRO-fit + DPMJET-II.4 ) ( MACRO-fit + DPMJET-II.53 ) Normalized d to the same livetime

M. Sioli, Blois FLUKA and HEMAS-DPM comparison HEMAS FLUKA ( MACRO-fit + DPMJET-II.4 ) ( MACRO-fit + DPMJET-II.53 ) Normalized d to the same livetime

M. Sioli, Blois Conclusions FLUKA can be used as a new high energy cosmic ray generator for underground and underwater physics The package has been developed using LNGS and ANTARES sites as examples; however, it can be easily extended to other sites, provided the map of the rock overburden or the depth of underwater sites First comparisons with other dedicated MC codes (HEMAS) Next steps:  Introduce other 1ry cosmic ray composition models  Comparisons with experimental data, e.g.: MACRO unfolded multiplicity distribution MACRO unfolded decoherence distribution Muon induced neutron flux at LNGS Muon charge ratio with OPERA/MINOS spectrometers

M. Sioli, Blois spares

M. Sioli, Blois Rock map LNGS  A map is an ascii file with three colums: zenith, azimuth and the corresponding rock depth (in m)  We have a topographical map from the Italian IGM (up to 94 deg): Distances are related to the central part of Hall B (including some badly known bins in the map)  Rock density from core sample campaign (2001)  Starting from these data, it’s possible to reproduce the map in every other place (Hall A, Hall C etc.)  interpolation of scattered data