MUPAGE: A fast muon generator MUons from PArametric formulas: a fast Generator of atmospheric m for neutrino telescopes (MUPAGE) M. Spurio, G. Carminati, A. Margiotta University of Bologna and INFN VLVnT08 - Toulon 22-24 April 2008 M. Spurio - VLVnT08 MUPAGE: A fast muon generator

Atmospheric muons in a VLVnT Atmospheric muons represent an important tool for neutrino telescopes Pointing capability (moon shadow) Detector calibration, PMTs efficiency … They can also represent a background: wrongly reconstructed tracks as upgoing events high energy muon bundles (diffuse flux background) Simultaneous muons from two different primary CR Muons in bundle seem to be particularly “dangerous”. M. Spurio - VLVnT08 MUPAGE: A fast muon generator

MUPAGE: A fast muon generator An alternative way to a full Monte Carlo simulation dedicated parameterization of the flux of single AND multiple atmospheric muons, based on a FULL MONTE CARLO simulation; see also VLVnT05 (Catania). It reproduces the underwater (and underground: MACRO) measurement of the muon flux This parameterization is now interfaced as a PHYSICS GENERATOR for detector-dependent simulation. M. Spurio - VLVnT08 MUPAGE: A fast muon generator

MUPAGE: Generator of underwater/ice muon bundles (C++ code) Parametric Formulas dNm/dEm=F(h,q;m,R) Muons on the “can” M. Spurio - VLVnT08 MUPAGE: A fast muon generator

Recipes: Primary CR flux + Parametric Formulas dNm/dEm=F(h,q;m,R) Recipes: Primary CR flux + Interaction model and shower propagation: HEMAS Hadronic interactions:DPMJET (no prompt muons) Muon transport: MUSIC Underwater muons M. Spurio - VLVnT08 MUPAGE: A fast muon generator

Underwater muons:data Multiplicity M. Spurio - VLVnT08 MUPAGE: A fast muon generator

MUPAGE: A fast muon generator (C++ code) Muons on the “can” Single Muons Bundles (for each m) Impact point on the can P=P(h,q) sampling lateral spread R(h,q) w.r.t. bundle axis muon coincident with bundle axis impact point according to R sampling energy according E(h,q) sampling energy according to E(h,q,m,R) M. Spurio - VLVnT08 MUPAGE: A fast muon generator

User input parameters Input: detector surface and physics information: CAN: cylinder surface surrounding detector active volume Input: detector surface and physics information: detector geometry, depth Medium: water/ice zenith angle range [0o,85o] max distance of muons from the shower axis in a bundle [100m] Range of muon energy [20,105] GeV Range bundle multiplicity [0,1000] Output: ascii files in table format Equivalent livetime of simulated run Example: Livetime=(8644 pm 12)s M. Spurio - VLVnT08 MUPAGE: A fast muon generator

Examples and application R,H ~ 300 m, 600 m Area =1.4 km2 depth ~ 2.5 km.w.e. Test on: SL3,SL4 2xIntel Xeon Quad Core, 2.33 GHz Sample 1 For data-MC comparison Sample 2 Diffuse n flux Background Livetime = 1 month Em> 20 GeV m=[0,100] 3.6 109 bundles 358 files (2h livetime) 600 GB (ascii) CPU: 360 h Livetime = 1 year  Em> 3000 GeV 6 m ranges: m=1,2,3, 4÷10, 11÷100, 101÷1000 0.45109 bundles 820 files 500 GB (ascii) CPU: 232 h M. Spurio - VLVnT08 MUPAGE: A fast muon generator

Ex. 1: Data/MC Angular distribution of atmospheric muons See talk of Margiotta (ANTARES) See talk of Amore (NEMO-Fase 1) M. Spurio - VLVnT08 MUPAGE: A fast muon generator

Ex.2:“Simultaneous” muon bundles in ANTARES (Sample 1) Atmospheric muon bundles from unrelated CRs can arrive on the detector simultaneously (Dt ≤ 4 ms) Tracks cannot be distinguished Strong dependence on detector depth For ANTARES Max Depth = 2450 m Pre- trigger rate ~ 3x10-2 Hz Post-trigger rate ~7x10-4 Hz Mis-reco as “upgoing”:<1/month For AMANDA~2-3 Hz (trigger) 1 2 M. Spurio - VLVnT08 MUPAGE: A fast muon generator

Ex. 3: Muon showers in ANTARES (Sample 1) Nucl.Instrum.Meth.A588:107-110,2008. e-Print: arXiv:0711.3158 [astro-ph] Study H.E. muon energy loss (through e+e− pair production, bremsstrahlung, and photonuclear interactions) The average dE/dx due to these effects is proportional to the muon energy. Figure: number of E.M. showers in Data and MC (mupage) M. Spurio - VLVnT08 MUPAGE: A fast muon generator

MUPAGE: A fast muon generator Ex.4: Moon Shadow Check the absolute orientation of the detector, i.e. the pointing Check the angular resolution A large data set is needed M. Spurio - VLVnT08 MUPAGE: A fast muon generator

Ex.5: Background for diffuse flux AMANDA-II:Phys.Rev.D76,042008(2007) MUPAGE can easily produce a large set of events for the bck evaluation 807 d 63 d M. Spurio - VLVnT08 MUPAGE: A fast muon generator

MUPAGE: A fast muon generator Conclusions Atmospheric muons are an important tool for nT MUPAGE : produce the event kinematics on the can with a CPU time (107 events/h) smaller than the one needed to produce the Cherenkov light inside the can Easy and ready to use Widely used in the ANTARES and NEMO coll. Below the CR knee: most of events in the nT are from CR below the knee the parameterization was tuned to reproduce the underwater measured flux and the underground MACRO results (multiplicity, decoherence, energy spectrum) Above the CR knee: HE background events maximum CR flux (no underestimate of the background) (A KM3nT can give constraint on the CR flux?) M. Spurio - VLVnT08 MUPAGE: A fast muon generator

MUPAGE: A fast muon generator Output: Table format Event number & bundle multiplicity - Track id - Coordinates of the impact point on the can surface - Direction cosines (vx, vy, vz) - Energy (GeV) - Arrival time in ns of the ith muon (0 for the first one) - GEANT particle identification number For each muon in bundle: M. Spurio - VLVnT08 MUPAGE: A fast muon generator

MUPAGE: A fast muon generator Horandel APP19(2003)193 4,75E-13 2,51E-13 1,31E-13 6,79E-14 3,47E-14 1,76E-14 8,80E-15 4,39E-15 2,19E-15 1,08E-15 5,33E-16 2,65E-16 1,31E-16 6,42E-17 3,10E-17 1,48E-17 6,81E-18 3,05E-18 M. Spurio - VLVnT08 MUPAGE: A fast muon generator

MUPAGE: A fast muon generator Flux vs. zenith angle M. Spurio - VLVnT08 MUPAGE: A fast muon generator

Single muon energy spectrum M. Spurio - VLVnT08 MUPAGE: A fast muon generator

MUPAGE: A fast muon generator M. Spurio - VLVnT08 MUPAGE: A fast muon generator

MUPAGE: A fast muon generator M. Spurio - VLVnT08 MUPAGE: A fast muon generator