2006-01-07 Spåtind Norway P.O.Hulth Cosmic Neutrinos and High Energy Neutrino Telescopes Spåtind 2006 lecture 1 Per Olof Hulth Stockholm University [email protected]
Dec 28, 2015
2006-01-07 Spåtind Norway P.O.Hulth
Cosmic Neutrinos and
High Energy Neutrino Telescopes
Spåtind 2006 lecture 1
Per Olof Hulth
Stockholm University
2006-01-07 Spåtind Norway P.O.Hulth
Neutrino sky 5-40 MeV
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Neutrino sky > 1 GeV
Nothing seen so far…….
2006-01-07 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
2006-01-07 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 < 1019 eV!
Not pointing back to the source!
2006-01-07 Spåtind Norway P.O.Hulth
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photonselectrons/positrons
muons neutrons
2006-01-07 Spåtind Norway P.O.Hulth
photonselectrons/positrons
muons neutronsIn the same time also atmospheric neutrinos from meson and muon decays!!
2006-01-07 Spåtind Norway P.O.Hulth
LHC
~E-2.7
~E-2.7
~E-3
Ankle
1 part km-2 yr-1
knee
1 part m-2 yr-1
T. Gaisser 2005
- The accelerators?
Nature accelerates particles 10 7 times the energy of LHC!
What are the sources?
Cosmic rays
2006-01-07 Spåtind Norway P.O.Hulth
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
2006-01-07 Spåtind Norway P.O.Hulth
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 0 decays you expect about the same flux of neutrinos!
• MicroquasarHESS gamma flux
2006-01-07 Spåtind Norway P.O.Hulth
Very High Energy Gamma sources
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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
2006-01-07 Spåtind Norway P.O.Hulth
Possible sources of UHE Cosmic Rays
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Active galaxies
Galaxy 3C296
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Gamma Ray Bursts
Cosmological sources!!
But what is it??
Source 9000 Million light years away!
2006-01-07 Spåtind Norway P.O.Hulth
Gamma Ray Burst ?
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• We expect to have neutrinos produced when the accelerated UHECR collides with matter or light in the vicinity of the source!
• Detect the neutrinos!
2006-01-07 Spåtind Norway P.O.Hulth
Observing neutrinos
Fermi acceleration of protons gives particle spectrum
dNp/dE~ E-2
Neutrino production at source: p+ or p+p collisions gives pionse- + e
Neutrino flavors:e : : 1:2:~0 at source1:1:1 at detector (?)
2006-01-07 Spåtind Norway P.O.Hulth
NGC 2300
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Dark matter searchThere 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
2006-01-07 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
2006-01-07 Spåtind Norway P.O.Hulth
Backgrounds
• Atmospheric muons– Produced in cosmic ray interactions above the
telescope. In AMANDA there are 106 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
2006-01-07 Spåtind Norway P.O.Hulth
log
[E2
· flu
x(E
) / G
eV c
m-2 s
-1 s
r-1]
-9
-7
-8
-6
-5
atmospheric
2 43 5 8 109 log (E /GeV)6 7
AGN
core
(SS)
AGN Jet (
MPR)
GRB (WB)
WB bound GZK
Required sensitivity
many specific models fornon-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/km2
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MeV GeV Tev PeV EeV
Different energy range for detectors
Underground
Optical Cherenkov
deep in water and ice
Radio, acoustic,
air showers
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Neutrino interactions in ice and water
The muon can travel several km in e.g. ice
< 1 degree
eV
e
e
Hadronic shower length
logE (10th of metres)
CCCharge Current
NCNeutral Current
2006-01-07 Spåtind Norway P.O.Hulth
275 GeV muon neutrino interaction in BEBC
1 m
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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!
2006-01-07 Spåtind Norway P.O.Hulth
e
low energy)“Cascades”
Length of cascades 10th of meters (L prop. logE)
Neutrino interactions in ice and water
CCCharge Current
2006-01-07 Spåtind Norway P.O.Hulth
e
high energy)“Cascades”
Length of cascades 10th of meters (L prop. logE)
Neutrino interactions in ice and water
CCCharge Current
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Neutrino cross-section
€
σ tot (νN) = 7.84 ×10−36cm2 Eν
1GeV
⎛
⎝ ⎜
⎞
⎠ ⎟0.363
For E< 104 GeV the x-section rises linearly with the energy
For E> 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.
2006-01-07 Spåtind Norway P.O.Hulth
Cross-section larger in e.g. -BH models
Standard Model
Strings
σ (m
b)
Micro black holes
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Shadowing effect of the Earth
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PeV acceptance around horizon
EeV acceptance above horizon
Shadowing effect of the Earth
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AMANDA-B10 efficiency for UHE neutrinos
upup
E-2 neutrino flux 2.5 1015eV -> 5.6 1018eV
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But for neutrinos the earth is transparent…
The tau neutrino will degrade in energy due to interactions in the Earth but will continue through.
2006-01-07 Spåtind Norway P.O.Hulth
The y-distributions
0 y 1.0 0 y 1.0
N N
(1-y)2
υq,υ q υ q,υq
Muon energy is harder in antineutrino interactions!
hadrons
muon
y = (Ehad - MN)/E
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y = Ehadrons /E
lepton = (1-y)E
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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….
CNB-> Z0-> decays
This process has been proposed to explain the UHECR events.
But you need a neutrino with 1024 eV energy..
2006-01-07 Spåtind Norway P.O.Hulth
up/down energy direction time
Atmospheric X
Diffuse neutrinos X X
Point sources; AGN, X X X
WIMPS
GRB X X X X
Reconstruction handles
X
XX
X
X X
X X X X
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Optical Cherenkov detection
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Detection principleO(km) long muon tracks
direction determination by Cherenkov light timing
15 m
O(10m) Cascades, e Neutral Current
Spåtind Norway P.O.Hulth
2006-01-07neutrino
muon
Cherenkov
light cone
Detectorinteraction
•The muon radiates blue light in its wake
•Optical sensors capture (and map) the light
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Neutrino interaction in AMANDA QuickTime™ and a
GIF decompressorare needed to see this picture.
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Acoustic Detection
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d
R
Particle cascade ionization heat pressure wave
P
t
50s
Attenuation length of sea water at 15-30 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
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Radio Detection
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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 ~ E2
nsec
negative charge is sweeped into developing shower, which acquiresa negative net chargeQnet ~ 0.25 Ecascade (GeV).
Threshold > 10 PeVC. Spiering
2006-01-07 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
2006-01-07 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.
2006-01-07 Spåtind Norway P.O.Hulth
Sydpolsfarare då och nu
Övervintra vid kusten
2006-01-07 Spåtind Norway P.O.Hulth
Sydpolsfarare då och nu
Tre timmars flyg från kusten
2006-01-07 Spåtind Norway P.O.Hulth
Sydpolen december 1911
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Sydpolen januari 1912
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Sydpolen november 2003
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2006-01-07 Spåtind Norway P.O.Hulth Joakim Edsjö SU
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