Published on October 3, 2007
Slide1: Earth-skimming UHE at the Fluorescence Detector of Pierre Auger Observatory astro-ph/0407638 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” Slide3: Terra Incognita II - Landscape & habitants Pampa Amarilla (Argentina)– Auger site The Pierre Auger Giant Array Observatory: High Energy Neutrino Physics The Pierre Auger Giant Array Observatory Slide5: 5 Auger numbers: Auger numbers 3000 km2 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: 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 Neutrino detection in Auger: Neutrino detection in Auger Neutrino initiated showers (HAS) have in principle different signatures from the hadronic ones. But... Are n 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 Slide9: 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) Tau neutrinos may have a chance! e± and ± are absorbed ± can emerge Slide10: Earth-Skimming + Regenerated UHE UHE from mountains The chances 10 Earth-skimming UHE : 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/0105067 Slide12: Upgoing shower (seen by Los Leones telescope) Slide13: Neutrino propagation in the Earth Iyer Dutta, Reno, Sarcevic PRD66 077302 (2002) One can expand the above set of equations in GF2 Slide14: The kernel K(E, E, ) gives the probability that: the survives for some distance z in the Earth ( Pa ) in z, z+d 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 ) The number of Up-going -induced showers in unit of t Slide15: Regenerated UHE Second order contribution, not relevant for final above the FD threshold (1018 eV) J.F. Beacom, P. Crotty, and E.W. Kolb 15 Slide16: 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) Neutrino Fluxes: 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 Slide18: 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 Cosmogenic Neutrinos Slide19: 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 2·1022 eV with luminosity (1 + z)3 up to z = 2. Bottom-up Kalashev et al. 01, 02 Semikoz & Sigl, hep-ph/0309328 Slide20: Kalashev, Kuzmin & Semikoz, 99 and 00 In this analysis 20 Slide21: Predictions for a top-down model with mX = 2·1013 GeV Top-down Kalashev et al. 01, 02 Semikoz & Sigl, hep-ph/0309328 Slide22: Top-Down and New hadrons Neutrinos Slide23: 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 < 10-5 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 Slide24: the different approaches give very similar cross-sections for the interesting energy range For E=1018 eV KSM 1.04 10-32 cm2 GRV98 1.16 10-32 cm2 CTEQ4 –DIS 1.02 10-32 cm2 Let us consider for example CC(N) For E =1021 eV KSM 1.17 10-31 cm2 GRV98 1.51 10-31 cm2 CTEQ4 –DIS 1.26 10-31 cm2 Slide25: CTEQ6 CTEQ4 Log10 E (GeV ) A good new ! 25 Slide26: Inelasticity parameter yCC=1 -E/E <yCC> is a function of energy Tau energy loss: Tau energy loss Koukolin & Petrukhin 71 Andreev & Bugaev 97 Bugaev & Shlepin 03 Slide29: By using the previous results one gets A(E) is the effective aperture Slide30: Not far from X. Bertou, P. Billoir, and S. Coutu 01 30 Slide32: max is the angle with respect to the horizontal for which is maximum the number of events Slide33: 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? Slide34: 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.