Montecarlo simulation of ?? interacting with mountains

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Earth-skimming UHE ?? at the Fluorescence
Detector of Pierre Auger Observatory
G. Miele Università di Napoli Federico II
Now2004
astro-ph/0407638 in collaboration with C. Aramo,
A. Insolia, A. Leonardi, L. Perrone, O. Pisanti
and D.V. Semikoz
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Terra Incognita II - Landscape habitants
Pampa Amarilla (Argentina) Auger site
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The Pierre Auger Giant Array Observatory
High Energy Neutrino Physics
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Auger numbers

• 3000 km2 area at an altitude of ? 1300 m a.s.l
  (Mendoza, Argentina)
• SD detector 1600 Cerenkov light detectors with
  a 1.5 km spacing (more than 400 already
  operating)
• FD detector 13000 photomultipliers for 24
  fluorescence telescopes located in 4 sites (duty
  cycle of 10) 12 already operating
• 3000 events yr-1 expected with energies above
  1019 eV and 30 events yr-1 above 1020 eV

http//www.auger.org
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Neutrino detection in Auger
Neutrino initiated showers (HAS) have in
principle different signatures from the hadronic
ones. But...
X. Bertou, P. Billoir, and S. Coutu 01
Travelling an atmospheric depth up to 360 m water
equivalent less than 1/1000 of crossing neutrinos
will interact. Thus atmosphere is almost
transparent for them.
Are n fluxes really detectable in Auger?
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Tau neutrinos may have a chance!
Fargion astro-ph/9704205, Halzen, Saltzberg
98 Becattini, Bottai 99,00 Iyer Dutta, Reno,
Sarcevic 00 Bertou et al. astro-ph/0104452,
Guerard ICRC01 Kusenko and Weiler,
hep-ph/0106071 Feng et al. hep-ph/0105067 Beacom,
Crotty, Kolb PRD66 021302 (2002)
e and ? are absorbed ? can emerge
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The ?? chances

• Earth-Skimming Regenerated UHE ??
• UHE ?? from mountains

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Earth-skimming UHE ??
J.L. Feng et al. hep-ph/0105067
EeV neutrinos have interaction lenght 500 Km
water equivalent in rock
?? travelling chords interaction lenght
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Upgoing ? shower (seen by Los Leones telescope)
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Neutrino propagation in the Earth
Iyer Dutta, Reno, Sarcevic PRD66 077302 (2002)
One can expand the above set of equations in GF2
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The number of Up-going ??-induced showers in
unit of t

• The kernel K(E?, E?, ?) gives the probability
  that
• the ?? survives for some distance z in the Earth
  ( Pa )
• ?? ? ? in z, zd z ( Pb )
• the ? comes out from the Earth before decaying (
  Pc )
• the energy of ? be E? for a given E? ( Pd )
• the ? decays producing a detectable shower ( Pe )

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Regenerated UHE ??
J.F. Beacom, P. Crotty, and E.W. Kolb

• Second order contribution, not relevant for
  final ? above the FD threshold (1018 eV)

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• Two kinds of approach
• Monte Carlo simulations (complex tool)
• Transport equations (perturbative but average
  approach)

But we need

• Neutrino fluxes
• Neutrino-Nucleon cross sections (???)
• Inelasticity parameter
• A reliable parameterization of ? energy loss in
  rock

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Neutrino Fluxes
Several kinds of models

• Cosmogenic Neutrinos (Bottom-Up) (surely there!)
• Z-burst (quite unlikely!)
• Neutrinos from decay of massive relics
  (Top-Down) (still not excluded by experiment)
• Exotic Hadrons (we hope so!)

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Cosmogenic Neutrinos
Transport equations which evolve the spectra of
nucleons, ?, e, neutrinos and antineutrinos,
assuming for proton the following injection
spectrum per comoving volume
Kalashev et al. 01, 02 Semikoz Sigl,
hep-ph/0309328
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Bottom-up
Kalashev et al. 01, 02 Semikoz Sigl,
hep-ph/0309328
Cosmogenic neutrino flux per flavour (red thick
line) produced by primary proton flux normalized
with AGASA and HiRes data. The UHECR sources are
assumed to inject a proton spectrum ? E-1 up to
21022 eV with luminosity ? (1 z)3 up to z 2.
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In this analysis
Kalashev, Kuzmin Semikoz, 99 and 00
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Kalashev et al. 01, 02 Semikoz Sigl,
hep-ph/0309328
Top-down
Predictions for a top-down model with mX
21013 GeV
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Top-Down and New hadrons Neutrinos
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Neutrino-Nucleon cross section
In the cross-section the parton distribution
functions (PDFs) enter as unknown quantities,
which have to be measured from deep-inelastic
experiments. For x lt 10-5 the uncertainty is
dominated by the lack of knowledge of PDF.
Gandhi, Quigg, Reno Sarcevic 98 approach, but
updated PDFs
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Let us consider for example ?CC(?N)

• For E?1018 eV
• KSM 1.04 10-32 cm2
• GRV98 1.16 10-32 cm2
• CTEQ4 DIS 1.02 10-32 cm2

• For E? 1021 eV
• KSM 1.17 10-31 cm2
• GRV98 1.51 10-31 cm2
• CTEQ4 DIS 1.26 10-31 cm2

the different approaches give very similar
cross-sections for the interesting energy range
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CTEQ6
CTEQ4
A good new !
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Log10 E ?(GeV )
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Inelasticity parameter yCC1 -E?/E?
ltyCCgt is a function of energy
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Tau energy loss
Bugaev Shlepin 03
Koukolin Petrukhin 71
Andreev Bugaev 97
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By using the previous results one gets
A(E?) is the effective aperture
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Not far from X. Bertou, P. Billoir, and S. Coutu
01
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?max is the angle with respect to the horizontal
for which is maximum the number of events
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Numerical Results for PAO-FD

• of events per year for ?CC(?N) (CTEQ6 DIS)
• GZK-WB 0.02
• GZK-L 0.04
• GZK-H 0.09
• TD 0.11
• NH 0.25

2 x ?CC(?N)
0.13
0.5 x ?CC(?N)
0.5
If Auger South North in 5 years one gains a
factor 10. So we could be just at threshold! What
about SD?
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Conclusions

• The prediction for the of events is strongly
  dependent on the ?-flux. Unavoidable!
• The computation of Earth-skimming events, seen by
  FD detector, seems to confirm the critical
  dependence on ?CC(? N).
• The available DEM of a large area around
  Malargüe allows for a realistic Montecarlo
  simulation of ??-induced events coming from
  mountains, but in order to perform a reliable
  simulation we need a good knowledge of very
  inclined showers and a their detectability by FD
  and/or SD.