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

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

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

Spåtind Norway P.O.Hulth 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 Why Neutrino Astronomy? Origin of High Energy cosmic rays Particle acceleration mechanisms in astrophysical sources Dark matter properties Neutrino properties The unknown, a new window to the universe!

Spåtind Norway P.O.Hulth   +  CMB -> e + + e - p+  CMB ->  + ->n+     +  GZK - neutrinos (Greisen, Zatsepin, Kusmin) P. Gorham Universe is not transparent for HE photons or nuclei! Protons deflected by magnetic field in space for E < eV! Not pointing back to the source!

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Spåtind Norway P.O.Hulth photonselectrons/positrons muonsneutrons

Spåtind Norway P.O.Hulth photonselectrons/positrons muonsneutrons In the same time also atmospheric neutrinos from meson and muon decays!!

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

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

Spåtind Norway P.O.Hulth Galactic sources Supernova are assumed to be able to accelerate particles up eV But the observed gammas could have electromagnetic orgin and not hadronic. If gammas are from  0 decays you expect about the same flux of neutrinos! Microquasar HESS gamma flux

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

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

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

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

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

Spåtind Norway P.O.Hulth Gamma Ray Burst ?

Spåtind Norway P.O.Hulth 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 Observing neutrinos Fermi acceleration of protons gives particle spectrum dN p /dE~ E -2 Neutrino production at source: p+  or p+p collisions gives pions       e - +   e Neutrino flavors: e :  :  1:2:~0 at source 1:1:1 at detector (?)

Spåtind Norway P.O.Hulth NGC 2300

Spåtind Norway P.O.Hulth 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 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 Backgrounds Atmospheric muons –Produced in cosmic ray interactions above the telescope. In AMANDA there are 10 6 downward 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 log [E 2 · flux(E ) / GeV cm -2 s -1 sr -1 ] atmospheric log (E /GeV) 67 AGN core (SS) AGN Jet (MPR) GRB (WB) WB bound GZK Required sensitivity many specific models for non-resolved sources...  Waxman, Bahcall (1999) derive generic limits from  limits on extragalactic p‘s   -ray flux... for discovering extraterrestrial neutrinos TeV PeV EeV E -2 flux 50 events/year/km 2

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

Spåtind Norway P.O.Hulth Neutrino interactions in ice and water   The muon can travel several km in e.g. ice < 1 degree           eV e    Hadronic shower length logE (10th of metres) CC Charge Current NC Neutral Current

Spåtind Norway P.O.Hulth 275 GeV muon neutrino interaction in BEBC 1 m 

Spåtind Norway P.O.Hulth Muon range in ice Muon propagator: MMC, Chirkin, D. 27th ICRC, HE 220, Hamburg 2001 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!

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

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

Spåtind Norway P.O.Hulth Neutrino cross-section For E  < 10 4 GeV the x-section rises linearly with the energy For E  > 10 4 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 Cross-section larger in e.g.  -BH models Standard Model Strings  (mb) Micro black holes

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

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

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

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

Spåtind Norway P.O.Hulth The y-distributions 0 y 1.0 NN (1-y) 2 Muon energy is harder in antineutrino interactions! hadrons muon y = (E had - M N )/E

Spåtind Norway P.O.Hulth y = E hadrons /E  lepton = (1-y)E

Spåtind Norway P.O.Hulth Z-bursts From Big Bang there should be about 330 neutrinos/cm 3 with an average energy of eV The ultimate neutrino experiment to detect these….    CNB -> Z 0 -> decays This process has been proposed to explain the UHECR events. But you need a neutrino with eV energy..

Spåtind Norway P.O.Hulth up/down energy direction time Atmospheric  X Diffuse neutrinos XX Point sources; AGN, XXX WIMPS GRB XXX X Reconstruction handles X XX X XX XXXX

Spåtind Norway P.O.Hulth Optical Cherenkov detection

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

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

Spåtind Norway P.O.Hulth Neutrino interaction in AMANDA

Spåtind Norway P.O.Hulth Acoustic Detection

Spåtind Norway P.O.Hulth d R Particle cascade  ionization  heat  pressure wave P t 50  s Attenuation length of sea water at kHz: a few km (light: a few tens of meters) → given a large initial signal, huge detection volumes can be achieved. Threshold > 10 PeV Maximum of emission at ~ 20 kHz C. Spiering

Spåtind Norway P.O.Hulth Radio Detection

Spåtind Norway P.O.Hulth e + n  p + e - e - ... cascade  relativist. pancake ~ 1cm thick,  ~10cm  each particle emits Cherenkov radiation  C signal is resultant of overlapping Cherenkov cones  for >> 10 cm (radio) coherence  C-signal ~ E 2 nsec negative charge is sweeped into developing shower, which acquires a negative net charge Q net ~ 0.25 E cascade (GeV). Threshold > 10 PeV C. Spiering

Spåtind Norway P.O.Hulth The Future We should be optimistic ! New York Times, December 29, 1932 Robert A. Millikan From S. Westerhoff, Lepton Photon 2005

Spåtind Norway P.O.Hulth Since we are in Norway. And that the point of gravity for High Energy Neutrino telescopes is at the South Pole which I will talk about tomorrow morning… A short historical comment.

Spåtind Norway P.O.Hulth Sydpolsfarare då och nu Övervintra vid kusten

Spåtind Norway P.O.Hulth Sydpolsfarare då och nu Tre timmars flyg från kusten

Spåtind Norway P.O.Hulth Sydpolen december 1911

Spåtind Norway P.O.Hulth Sydpolen januari 1912

Spåtind Norway P.O.Hulth Sydpolen november 2003

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Spåtind Norway P.O.Hulth Joakim Edsjö SU

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