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Cosmic Neutrinos and High Energy Neutrino Telescopes Spåtind 2006 lecture 1

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Cosmic Neutrinos and High Energy Neutrino Telescopes Spåtind 2006 lecture 1

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  1. Cosmic Neutrinos and High Energy Neutrino TelescopesSpåtind 2006 lecture 1 Per Olof Hulth Stockholm University Spåtind Norway P.O.Hulth

  2. Neutrino sky 5-40 MeV Spåtind Norway P.O.Hulth

  3. Neutrino sky > 1 GeV Nothing seen so far……. Spåtind Norway P.O.Hulth

  4. Outline • Lecture 1 • Why do we expect to see cosmic neutrinos? • Cosmic rays • Dark matter • Neutrino detection principles • Lecture 2 • Running High Energy Neutrino telescopes • Some physics results • Near future telescopes Spåtind Norway P.O.Hulth

  5. Universe is not transparent for HE photons or nuclei! g +gCMB -> e+ + e- p+gCMB -> D+->n+p+ m++nm GZK - neutrinos (Greisen, Zatsepin, Kusmin) Protons deflected by magnetic field in space for E < 1019 eV! Not pointing back to the source! P. Gorham Spåtind Norway P.O.Hulth

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  13. electrons/positrons photons muons neutrons Spåtind Norway P.O.Hulth

  14. electrons/positrons photons muons neutrons In the same time also atmospheric neutrinos from meson and muon decays!! Spåtind Norway P.O.Hulth

  15. Cosmic rays T. Gaisser 2005 ~E-2.7 • - The accelerators? • Nature accelerates particles 10 7 times the energy of LHC! • What are the sources? knee 1 part m-2 yr-1 ~E-3 Ankle 1 part km-2 yr-1 ~E-2.7 LHC Spåtind Norway P.O.Hulth

  16. The size of the Universe “LHC” accelerator? R To use LHC magnets to deliver 1020 eV we need a radius of the accelerator to be about 1.5 times the distance Earth -Sun Spåtind Norway P.O.Hulth

  17. Galactic sources • Supernova are assumed to be able to accelerate particles up 1016 eV • But the observed gammas could have electromagnetic orgin and not hadronic. • If gammas are from p0 decays you expect about the same flux of neutrinos! • Microquasar HESS gamma flux Spåtind Norway P.O.Hulth

  18. Very High Energy Gamma sources Spåtind Norway P.O.Hulth

  19. Ultra High Energy Cosmic Rays • UHECR are assumed to be extra galactic • There are still uncertainties about flux. • No obvious sources for the particles > 1019.5 eV within 20 Mpc…? • GZK effect observed? Shigeru Yoshida, ICRC 2005, Pune Spåtind Norway P.O.Hulth

  20. Possible sources of UHE Cosmic Rays Spåtind Norway P.O.Hulth

  21. Active galaxies Galaxy 3C296 Spåtind Norway P.O.Hulth

  22. Gamma Ray Bursts Source 9000 Million light years away! Cosmological sources!! But what is it?? Spåtind Norway P.O.Hulth

  23. Gamma Ray Burst ? Spåtind Norway P.O.Hulth

  24. We expect to have neutrinos produced when the accelerated UHECR collides with matter or light in the vicinity of the source! • Detect the neutrinos! Spåtind Norway P.O.Hulth

  25. Observing neutrinos • Fermi acceleration of protons gives particle spectrum • dNp/dE~ E-2 • Neutrino production at source: • p+ or p+p collisions gives pions • p -> mn + nm • mn -> e- + nm+ ne • Neutrino flavors: • e :  :  • 1:2:~0 at source • 1:1:1 at detector (?) Spåtind Norway P.O.Hulth

  26. NGC 2300 Spåtind Norway P.O.Hulth

  27. Dark matter search There exists about 5 times more dark matter in the universe than our baryonic matter “Best” dark matter candidate: neutralino Neutralinos are trapped in large objects like the Sun and Earth and self-annihilate. Search for neutrinos from the centers of Earth and Sun See talks by Thomas Burgess and Gustav Wikström today Spåtind Norway P.O.Hulth

  28. Neutrino Astronomy • + Neutrinos penetrate the whole Universe • +Neutrinos direction points back to the source • + Neutrinos are produced at the sources of the cosmic rays • + Neutrinos are not reprocessed at the sources • + Neutrinos expected from dark matter particle annihilation • - Low expected flux of extragalactic neutrinos • - Small cross section • - Needs gigantic detector volumes Spåtind Norway P.O.Hulth

  29. Backgrounds • Atmospheric muons • Produced in cosmic ray interactions above the telescope. In AMANDA there are 106downward going atmospheric muons for every upward going atmospheric neutrino induced muon -> select only upward going muons as neutrino candidates. The Earth acts as a filter. • Atmospheric neutrinos Spåtind Norway P.O.Hulth

  30. Required sensitivity ... for discovering extraterrestrial neutrinos many specific models for non-resolved sources ... -5 atmospheric E-2 flux -6  Waxman, Bahcall (1999) derive generic limits from  limits on extragalactic p‘s -ray flux log [E2 · flux(E) / GeV cm-2 s-1 sr-1] -7 GZK WB bound AGN core (SS) -8 AGN Jet (MPR) 50 events/year/km2 GRB (WB) -9 log (E /GeV) 2 3 4 5 6 7 8 9 10 Spåtind Norway P.O.Hulth TeV PeV EeV

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  32. Different energy range for detectors Radio, acoustic, air showers Underground Optical Cherenkov deep in water and ice MeV GeV Tev PeV EeV Spåtind Norway P.O.Hulth

  33. Neutrino interactions in ice and water The muon can travel several km in e.g. ice   CC Charge Current Fnm<0.65o/En0.48 En = 1012eV < 1 degree Hadronic shower length logE (10th of metres)  e  t NC Neutral Current  e  t Spåtind Norway P.O.Hulth

  34. 275 GeV muon neutrino interaction in BEBC m- 1 m Spåtind Norway P.O.Hulth

  35. Muon range in ice The muon starts to loose energy above 500 GeV to pair production, bremstrahlung The muon will be dressed up by many e+ and e-. More Cherenkov light! Muon propagator: MMC , Chirkin, D. 27th ICRC, HE 220, Hamburg 2001 Spåtind Norway P.O.Hulth

  36. Neutrino interactions in ice and water  e CC Charge Current “Cascades” t (low energy) Length of cascades 10th of meters (L prop. logE) Spåtind Norway P.O.Hulth

  37. Neutrino interactions in ice and water  e CC Charge Current “Cascades” t (high energy) t Length of cascades 10th of meters (L prop. logE) Spåtind Norway P.O.Hulth

  38. Neutrinocross-section For En < 104 GeV the x-section rises linearly with the energy For En > 104 GeV (due to the W-boson propagator: Cross-section measured up to 300 GeV. Up to about 10 TeV based on structure functions from HERA. Above different extrapolations. Spåtind Norway P.O.Hulth

  39. Cross-section larger in e.g. m-BH models Micro black holes s (mb) Strings Standard Model Spåtind Norway P.O.Hulth

  40. Shadowing effect of the Earth Spåtind Norway P.O.Hulth

  41. Shadowing effect of the Earth PeV acceptance around horizon EeV acceptance above horizon Spåtind Norway P.O.Hulth

  42. AMANDA-B10 efficiency for UHE neutrinos up up E-2 neutrino flux 2.5 1015eV -> 5.6 1018eV Spåtind Norway P.O.Hulth

  43. But for t-neutrinos the earth is transparent… t t t The tau neutrino will degrade in energy due to interactions in the Earth but will continue through. Spåtind Norway P.O.Hulth

  44. The y-distributions N N y = (Ehad - MN)/En (1-y)2 0 y 1.0 0 y 1.0 Muon energy is harder in antineutrino interactions! muon hadrons Spåtind Norway P.O.Hulth

  45. y = Ehadrons /En Elepton = (1-y)En Spåtind Norway P.O.Hulth

  46. Z-bursts • From Big Bang there should be about 330 neutrinos/cm3 with an average energy of 0.0004 eV • The ultimate neutrino experiment to detect these…. n+ nCNB-> Z0-> decays This process has been proposed to explain the UHECR events. But you need a neutrino with 1024 eV energy.. Spåtind Norway P.O.Hulth

  47. Reconstruction handles up/down energy direction time Atmospheric nm X Diffuse neutrinos X X Point sources; AGN, X X X WIMPS GRB X X X X X X X X X X X X X X Spåtind Norway P.O.Hulth

  48. Optical Cherenkov detection Spåtind Norway P.O.Hulth

  49. O(km) long muon tracks  15 m direction determination by Cherenkov light timing Detection principle O(10m) Cascades, nentNeutral Current Spåtind Norway P.O.Hulth

  50. Cherenkov light cone muon interaction Detector • The muon radiates blue light in its wake • Optical sensors capture (and map) the light neutrino Spåtind Norway P.O.Hulth