All lepton generation and propagation with MMC

1. All lepton generation and propagation with MMC Dmitry Chirkin, UCB/LBNL AMANDA meeting, Uppsala, 2004

2. More than 4700 new lines of code ALMC event visualizer Main program Neutrino cross sections due to Cteq 6.1 PDF parameterization, Preliminary Earth model impl. Gaisser and Volkova flux parameterizations; Atmospheric corrections due to hep-0407078 Interface to native languages, e.g, C/C++/Fortran New MMC package contents

3. AtmFlux is the main program for processing all 12 leptons: • f2k stream processor, propagates (~)(nu_)e/mu/tau([+-]) • generator: generates and propagates fluxes of: • atmospheric muons and muon- and electron neutrinos • phenomenological charm contribution • E^[-g] fluxes of (~)nu_e, (~)nu_mu, and (~)nu_tau • generator only: generated fluxes are placed on the Earth surface and are output without having been propagated • all of the above in the i3m native interface module, which was used for IceCube MMC generator/propagator • ALMC event visualizer, can be used as: • visualizer application • same with event f2k output • internet applet (see MMC homepage) New features

4. Used as given, in native Fortran code (files Cteq61Pdf.f and cteq6m.tbl are included in the MMC distribution) • Therefore, it should be very easy to update CTEQ parameterization when the new version comes out • Compiles with “ammc –ctq” to produce the libcteq.so library. “source ammc –ctq” to update the library path before running mmc programs (AtmFlux, NeutrinoTot, etc.) • MMC will try to do the following when neutrino cross sections are initialized: • look for the .*.gen_neutrino*.data file; if fails: • look for the .cteqPDF_*.data file (48239 bytes); if fails: • try to load the libcteq.so library •  therefore if .cteqPDF_raw.data or .*.gen_neutrino*.data files are present, it is possible to avoid loading native library and, e.g., run MMC in a web browser CTEQ PDF parameterization library

5. Neutrino cross sections • Neutrino interactions implemented in MMC: • charged current (CC) • (nu+Nmu+…) • neutral current (NC) • (nu+Nnu+…) • Glashow resonance: • ~nu_e+eW- • ~nu_e+e • ~nu_mu+mu • ~nu_tau+tau • hadrons • oscillations: • nu_mu nu_tau

6. Tau decay is implemented by: • 3-body decay for lepton decays • 2-body decay into pi, K, or 3 resonances (approximation). • Polarization effects are not calculated, so very high energy event distribution might be somewhat incorrect. • All regeneration is taken care of by recursive routine calling. Tau decay, regeneration, etc.

7. Neutrino zenith angle distribution Events from atmospheric muon and electron neutrinos with energies above 10 TeV. Parameterized version uses more precise integration for table calculation than the non-parameterized, whose precision is insufficient for the statistics shown.

8. Neutrino zenith angle distribution Replacing ice medium used by the (charged lepton) propagator under the ice layer with rock and reducing ice density in the top 200 meters changes this distribution

9. Neutrino flux grows as E-2.7-3.7 with low energy cutoff  a lot more neutrinos must be analyzed for the energy threshold of 10 GeV • Neutrino cross sections get smaller as E1 as the energy gets smaller • It therefore takes many orders of magnitude more time to calculate the flux with 103 times smaller threshold. • MMC employs the following approximation (enabled by –mF=[factor], where factor can be, e.g., 10. For each zenith angle the ratio of Earth mass overburden at that angle to neutrino interaction length is evaluated. If this ratio is greater than 10, then the neutrino interaction cross sections are scaled up to bring this ratio to 10. The flux evaluated on the Earth surface is scaled down by the same amount. • At energies higher than 10 TeV neutrino propagation through the Earth (including all regeneration effects) seems to be sufficiently fast so that matrix differential equation optimization approach (vs. Monte Carlo, as used by Juliet) does not seem to be necessary. Neutrino distributions with Ecut=10 GeV

10. Neutrino distributions with Ecut=10 GeV Neutrino flavor oscillations affect the zenith angle distribution of events which contain at least one muon inside the detector cylinder. Since latitude-dependent geomagnetic cutoff is not calculated, a fixed 10 GeV cutoff is applied.

11. zenith angle distr. tau neutrino E^(-2) isotropic spectrum, showing the "double-bang" event (Ecut=1 PeV) All Lepton Monte Carlo web applet Atm. neutrinos with energies above 10 TeV deposited energy

12. MMC has grown into an all-lepton generator/propagator • For simple runs it can replace 3 programs: • CORSIKA; be aware that it generates only single muon events, and those are generated according to fits to CORSIKA (as described in hep-ph/0407078) • NUSIM/ANIS; same applies here (muonneutrino) • MMC/MUMf2k/mudedx  today this is default • Has both strengths and weaknesses compared to other neutrino generators; can be used for systematics studies. • Neutrino propagator/generator is fully integrated with the muon/tau propagator. • It is possible to interface MMC with native code using the i3module library (included into the distribution, compiles with “source ammc –i3m”); also can call native routines. Conclusions