Earth-skimming UHE  at the Fluorescence Detector of Pierre Auger Observatory astro-ph/ in collaboration with C. Aramo, A. Insolia, A. Leonardi, L. Perrone, O. Pisanti and D.V. Semikoz Now2004 G. Miele Università di Napoli “Federico II”

Terra Incognita II - Landscape & habitants Pampa Amarilla (Argentina)– Auger site

High Energy Neutrino Physics The Pierre Auger Giant Array Observatory

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Auger numbers 3000 km 2 area at an altitude of  1300 m a.s.l (Mendoza, Argentina); SD detector: 1600 Čerenkov light detectors with a 1.5 km spacing – (more than 400 already operating); FD detector: photomultipliers for 24 fluorescence telescopes located in 4 sites (duty cycle of 10%) – 12 already operating ; 3000 events yr -1 expected with energies above eV and 30 events yr -1 above eV;

Neutrino detection in Auger N eutrino initiated showers (HAS) have in principle different signatures from the hadronic ones. But... Are fluxes really detectable in Auger? 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. X. Bertou, P. Billoir, and S. Coutu 01

Fargion astro-ph/ , Halzen, Saltzberg 98 Becattini, Bottai 99,00 Iyer Dutta, Reno, Sarcevic 00 Bertou et al. astro-ph/ , Guerard ICRC01 Kusenko and Weiler, hep-ph/ Feng et al. hep-ph/ Beacom, Crotty, Kolb PRD (2002) Tau neutrinos may have a chance! e ± and  ± are absorbed  ± can emerge

Earth-Skimming + Regenerated UHE  UHE  from mountains The  chances 10

Earth-skimming UHE   travelling chords ~ interaction lenght EeV neutrinos have interaction lenght ~ 500 Km water equivalent in rock J.L. Feng et al. hep-ph/

Upgoing  shower (seen by Los Leones telescope)

Neutrino propagation in the Earth Iyer Dutta, Reno, Sarcevic PRD (2002) One can expand the above set of equations in G F 2

The kernel K(E, E ,  ) gives the probability that: 1. the  survives for some distance z in the Earth ( P a ) 2.    in z, z+d z ( P b ) 3. the  comes out from the Earth before decaying ( P c ) 4. the energy of  be E  for a given E ( P d ) 5. the  decays producing a detectable shower ( P e ) The number of Up-going  -induced showers in unit of t

Regenerated UHE  Second order contribution, not relevant for final  above the FD threshold (10 18 eV) J.F. Beacom, P. Crotty, and E.W. Kolb 15

But we need: Neutrino fluxes Neutrino-Nucleon cross sections (   ) Inelasticity parameter A reliable parameterization of  energy loss in rock Two kinds of approach: Monte Carlo simulations (complex tool) Transport equations (perturbative but average approach)

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!) Several kinds of models Neutrino Fluxes

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/ Cosmogenic Neutrinos

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 2·10 22 eV with luminosity  (1 + z) 3 up to z = 2. Bottom-up Kalashev et al. 01, 02 Semikoz & Sigl, hep-ph/

Kalashev, Kuzmin & Semikoz, 99 and 00 In this analysis 20

Predictions for a top-down model with m X = 2·10 13 GeV Top-down Kalashev et al. 01, 02 Semikoz & Sigl, hep-ph/

Top-Down and New hadrons Neutrinos

In the cross-section the parton distribution functions (PDF’s) enter as unknown quantities, which have to be measured from deep-inelastic experiments. For x < the uncertainty is dominated by the lack of knowledge of PDF. Neutrino-Nucleon cross section Gandhi, Quigg, Reno & Sarcevic ’98 approach, but updated PDF’s

the different approaches give very similar cross- sections for the interesting energy range For E =10 18 eV KSM cm 2 GRV cm 2 CTEQ4 –DIS cm 2 Let us consider for example  CC ( N) For E =10 21 eV KSM cm 2 GRV cm 2 CTEQ4 –DIS cm 2

CTEQ6 CTEQ4 Log 10 E (GeV ) A good new ! 25

Inelasticity parameter y CC =1 -E  /E is a function of energy

Tau energy loss Koukolin & Petrukhin 71 Andreev & Bugaev 97 Bugaev & Shlepin 03

By using the previous results one gets A(E ) is the effective aperture

Not far from X. Bertou, P. Billoir, and S. Coutu 01 30

 max is the angle with respect to the horizontal for which is maximum the number of events

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 TD0.11 NH x  CC ( N) 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?

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.