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Investigation of backgrounds for horizontal neutrino showers at ultra-high energy

Investigation of backgrounds for horizontal neutrino showers at ultra-high energy. Oana Ta ş c ă u 1 , Ralph Engel², Karl-Heinz Kampert 1 , Markus Risse 1 1 Bergische Universität, Wuppertal ² Forschungszentrum, Karlsruhe. Pierre Auger Observatory. Surface Array 1600 detector stations

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Investigation of backgrounds for horizontal neutrino showers at ultra-high energy

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  1. Investigation of backgrounds for horizontal neutrino showers at ultra-high energy Oana Taşcău1, Ralph Engel², Karl-Heinz Kampert1, Markus Risse1 1Bergische Universität, Wuppertal ² Forschungszentrum, Karlsruhe

  2. Pierre Auger Observatory Surface Array 1600 detector stations 1.5 km spacing Fluorescence Detectors 4 Telescope stations 6 Telescopes / station 24 Telescopes total

  3. ~30 atm Neutrinos: important bi-product in Auger A neutrino can induce a young horizontal shower ! h ν µ h em 1 atm

  4. Outside FoV Xmaxsubshower seen by FD!! F D Background! I. Muon induced Background ? Catastrophic energy loss p, A ±

  5. Types of Muons p, A Charmed particles D±, D°, c… ,  Low energy (model dependent) HE (>Auger threshold)   prompt conventional

  6. Example of Individual  Profiles CORSIKA 6.500 - QGSJET, Fluka - curved atmosphere, thinning option (εth=10-6), =87° N Nmax at E=1017 eV FD threshold Eµ=1019 eV Eµ=1017eV Slant depth g/cm²

  7. Atmospheric Vertical µ-Fluxes The theoretical uncertanties are huge!(due to unknowncharm X-section) Prompt lepton cookbook – C.G.C. Costa, APP 16 (2001) 193;Zas(A) = Zas, Halzen, Vazques, APP 1 (1993) 297; C=0.1totinel

  8. Vertical vs Horizontal - flux MRS: At high energies all estimations may be up-scaledby a factor of 10! horizontal vertical A.D. Martin, M.G. Ryskin and A. M. StastoActa Phys. Polon. B34 (2003) 3273; astro-ph/0302140

  9. X1 Estimate of µ-inducedHorizontal Event Rate in Auger  10 km Pno-int Xo Xint Pint X2

  10. D = Duty cycle 10%; 10 x vertical flux for horizontal events • Solid angle: • Integral over the energy for the event rate: • Integral over the volume • The probability to have interactions inside the volume CORSIKA 6.500

  11. TIG GGV ZAS 80°- 90° 1.4 x 10-5 0.0014 0.14 60°- 90° 4 x 10-5 0.004 0.4 Bkg to Signal < 0.006%; <0.1% <0.6%; <10% 60%, 100% HE  induced shower events/year G. Miele et al PLB 634 (2006) 137 Results HE muon-induced shower events/year : TIG: Thunman, Ingelman, Gondolo APP 5; GGV: Gelmini, Gondolo, Varieschi, PRD 61

  12. II Photonic Origin Background • 1.  showers develop deep due to the LPM suppression • 2. Are there very deep subcascades, after the main Xmax, from the high energy secondaries (LPM)?

  13. Elongation Rate Xmax > XmaxH

  14. CORSIKA  Library Mass Production Chain 26 000 CORSIKA 6.500 QGSjet Gheisha SLANT Curved Thinning Upward 26 versions of 1000 showers Thinning (optimized) = 60°, 69°, 75°, 80°, 85°, 89° Depth step 1g/cm², 5 g/cm², 10g/cm² Obs. Level = 1 450 m, 0, -1000 m All long files have to be corrected …some long files have to be corrected CORSIKA 6.538 QGSjet Gheisha SLANT Curved Thinning Upward 15 versions of 5000 9 versions of 10000 5 versions of 1 000 ALICEnext 180 000

  15. Xmax distribution > 2000 g/cm² 1% of -showers show a late development Work in progress… Note: N/NH ≤ 2% @ 1019 eV; ≤ 30% @ 4x1019 eV

  16. Conclusions • HE muons from heavy flavor decay can induce young horizontal showers similar to the signatures • The theoretical uncertanties are large… • For 2 models the predicted background rates are low enough => VHE  with Auger! • For the most exotic perspective (Zas), one could think about an interesting capability to be sensitive to charm! • The background for the  detection by FD is investigated further for primary photons

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