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 Universit di Napoli Federico II Terra Incognita II - Landscape & habitants Pampa Amarilla (Argentina) Auger site High Energy Neutrino Physics The Pierre Auger Giant Array Observatory 5 Auger numbers 3000 km 2 area at an altitude of 1300 m a.s.l (Mendoza, Argentina); SD detector: 1600 erenkov 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 210 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 = 210 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 (PDFs) 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 PDFs 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 Malarge 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.