All lepton generation and propagation with MMC

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All lepton generation and propagation with MMC
Dmitry Chirkin, UCB/LBNL
AMANDA meeting, Uppsala, 2004
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New MMC package contents
More than 4700 new lines of code
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New features

• 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)

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CTEQ PDF parameterization library

• 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

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Neutrino cross sections

• Neutrino interactions implemented in MMC
• charged current (CC)
• (nuN?mu)
• neutral current (NC)
• (nuN?nu)
• Glashow resonance
• nu_ee?W-?
• nu_ee
• nu_mumu
• nu_tautau
• hadrons
• oscillations
• nu_mu ??nu_tau

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Tau decay, regeneration, etc.

• 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.

Program MMC ANIS NUSIM Juliet
Tau decay polarization no yes n/a yes
Tau hadronic decay 2 body TAUOLA n/a 2 body
Regeneration effects yes yes no yes
Built-in muon/tau prop. MMC/MMC no/approx. mudedx/no Juliet/Juliet
HE nu crs. extrapolation 1(power law) 2 2 1 (more?)
Flavor oscillations yes (2 flavor) no no no
Energy span, GeV complete complete complete 106-1012
Param. table generation 5-10 min days unknown unknown
Integr./Interpol. precision 3-6 romberg fixed fixed fixed
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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.
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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
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Neutrino distributions with Ecut10 GeV

• 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 mFfactor, 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.

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Neutrino distributions with Ecut10 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.
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All Lepton Monte Carlo web applet
Atm. neutrinos with energies above 10
TeV deposited energy
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Conclusions

• 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.