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This workshop presentation discusses ANIS, an event generator for simulating neutrino interactions of all flavors. It covers the implementation of physics, resulting event distributions, relevant Standard Model processes, Tau decay, neutrino propagation, regeneration effects, and event distributions for electron-neutrinos and neutrino-induced muons. The limitations and potential improvements of ANIS are also discussed.
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ANIS: All Neutrino Interaction Simulation Marek Kowalski DESY-Zeuthen Workshop on Ultra High Energy Neutrino Telescopes Chiba, 30.7.2003
Content • Introduction • The implementation of the physics: neutrino interaction, propagation,… • Some resulting event distributions
ANIS • Event generator for neutrino events of all flavors • C++ code, using the CLHEP::HepMC library
ANIS FluxDriver HepMC::Event Propagation Interactions HepMC::Event Decays n - events FinalVolume
Interaction Processes • Relevant Standard Model • Processes are implemented: • CC, NC (structure function: CTEQ5 & two different extrapolations) • Glashow resonance • CC and NC cross-section data and final states are stored in tables. • Tables of final states consisting of Feynman x and y generated before and sampled from by ANIS.
Flexible Design New processes easily added. Examples: • production of mini Black Holes • Instantons,… class SigmaNew : public Sigma { public: double SigmaNew::GetSigma void SigmaNew::FillVertex }
Tau decay • Tau decay done using TAUOLA • Polarization taken into account • Table of final states (at rest) generated from which ANIS samples
Neutrino Propagation • Preliminary Earth Model (+ 3 km ice) • Regeneration effects included - NC: n + N -> X + n - CC: nt+ N -> X + t -> n (+ nm , ne) - Glashow resonance: W -> l + nl - Any new processes • All secondary neutrinos are taken into account and further propagated
g=2 Example: Regeneration of nt Ratio of neutrino flux at the detector to neutrino flux at the surface (F(E)~E-g) g=1
Once final volume reached… • Neutrino interaction simulated inside cylinder of variable size • In case muons are generated further propagation necessary (e.g. using Dimas MMC, …)
Some Event Distributions Event rates of electron-neutrinos in a km3 detector > >
Neutrino-induced Muons • Simulation of mono energetic nm. • Detector 1.7 km deep in ice. • Muon propagation done with MMC. absorption target
Some current limitations of ANIS • Tau propagation done with a+bE approximation (valid up to EHE energies). Can be improved. • Angle between neutrino – lepton neglected during propagation. Only for final CC interaction included (important for resolution studies at low energies). • Weighted events: Physical flux (e.g atmospheric or AGN,..) is obtained by reweighting the events.
Conclusions • (Rather) precise event generator existing for simulating neutrino events of all flavors • Easily extendable to new physics