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Emilio Migneco. Erice ISCRA School 2004. Introduction to High energy neutrino astronomy. Topics. 1) Introduction to high energy neutrino astronomy Motivations for HE neutrino astronomy HE neutrino sources Neutrino telescopes operation principles Backgrounds - PowerPoint PPT PresentationTRANSCRIPT
E. Migneco Erice ISCRA, July 2-13 2004
Introduction to High energy neutrino astronomy
Erice ISCRA School 2004
Emilio Migneco
E. Migneco Erice ISCRA, July 2-13 2004
Topics
1) Introduction to high energy neutrino astronomy
Motivations for HE neutrino astronomyHE neutrino sourcesNeutrino telescopes operation principlesBackgrounds
2) Future cubic kilometer arrays
Review of existing detectors and projectsFuture detectors:
impact of site parametersarchitectureexperimental challengessimulations and expected performances
1) Introduction to high energy neutrino astronomy
Motivations for HE neutrino astronomyHE neutrino sourcesNeutrino telescopes operation principlesBackgrounds
2) Future cubic kilometer arrays
Review of existing detectors and projectsFuture detectors:
impact of site parametersarchitectureexperimental challengessimulations and expected performances
E. Migneco Erice ISCRA, July 2-13 2004
Neutrino astronomy
Neutrinos are elementary particles with “special” properties:
• light
• neutral
• interact by weak force
Good astrophysical probes:
not deflected point back to the source
not absorbed travel Gpc distances (overcome GZK effect)
But they are difficult to detect
I have done a terrible thing I invented a particle that cannot be detectedW.Pauli
E. Migneco Erice ISCRA, July 2-13 2004
The known cosmic neutrino spectrum
?
SuperKamiokande neutrino image of the Sun
HST image of SN 1987A
The measurements of (low energy) solar, SN and
atmospheric neutrino fluxes is permitting to solve open
questions in astrophysics, nuclear and particle physics... Davis and Koshiba Nobel laureates 2002
E. Migneco Erice ISCRA, July 2-13 2004
High energy astrophysics
The detection of high energy gammas and CR are
milestones in modern astrophysics but there are still open
questions
• Particle acceleration mechanism in astrophysical sources
• Identification of high energy CR sources
• Solution of UHECR puzzle
• Heavy dark matter content in the Universe
The detection of high energy gammas and CR are
milestones in modern astrophysics but there are still open
questions
• Particle acceleration mechanism in astrophysical sources
• Identification of high energy CR sources
• Solution of UHECR puzzle
• Heavy dark matter content in the Universe
E. Migneco Erice ISCRA, July 2-13 2004
The high energy cosmic ray standard paradigm
Ankle
Galactic nuclei
E-3
Sources of high energy protons exists and dominate the CR
spectrum at E> 1018.5 eV
Knee
Gaisser
protons
E-2.7
Galactic protonsE-2.7
E. Migneco Erice ISCRA, July 2-13 2004
To
p D
ow
n
“Top – Down” and “Bottom – Up” processes
MX~102124 eV
CR 1021 eV
decay or annihilation
acceleration
p,e at restgammas and neutrinos
gammas and neutrinos
Bo
tto
m
U
p
CR 1021 eV E-2 spectrum
flat spectrum
E. Migneco Erice ISCRA, July 2-13 2004
Astrophysical sources of UHE particles
•Large cosmic objects
•Intense magnetic field
•High shockwave velocity
18max shockE Z B[ G] L[kpc] 10 eV
HillasFermi acceleration to high energies requires
GRB
GRBL1052 erg/sec
Bright AGNL1047 erg/sec
These values are typical for very bright sources
Emax =1020 eV
E. Migneco Erice ISCRA, July 2-13 2004
Possible extra Galactic sources of CR: AGN
QSO GB1508+5714 Chandra
The term AGNs (Active Galactic Nuclei) gathers a number of astrophysical objects
6 8BHM 10 M • Massive Black Hole
• Accretion disk (UV + lines)
• Collimated jets
QSO 3C273QSO 3C279
EGRET
10
The brightest observed steady sources:
L=1042 1047 erg/s
When the jet is directed towards the Earth luminosity increases ”Blazars”
E. Migneco Erice ISCRA, July 2-13 2004
Possible extra Galactic sources of CR: GRB
GRB (Gamma Ray Bursts) are the most
powerful emissions of gamma rays
ever observed.
Happens at cosmological distances
The observation rate is few/day
GRB have recentely been shown to be
associated with SN, as indicated by the
GRB030329 – SN 2003dh correlation
10MM
s
300
GRB 030329ESO
L = 1051 1053 erg/s
t 1100 s (1/3 <2
sec)
(GRB 030329 z=0.17)
E. Migneco Erice ISCRA, July 2-13 2004
Limits of HE gamma and proton astronomy
The UHE CR and gamma horizon is limited by
interactions with low energy background
radiation
The UHE CR and gamma horizon is limited by
interactions with low energy background
radiation
E. Migneco Erice ISCRA, July 2-13 2004
Absorption of high energy photons and protons
NCMBR N (GZK)
nCMBR ~ 400 cm-3
p~ 100 barn
ECMBR ~ 6.6·10-4 eV Ep ~ 1019.5 eV
pCMBRatt
p CMBR
1<50 Mpc
n
Guaranteed sources of neutrinos
IR,CMBR e+e-
CMBR,IRatt
CMBR,IR
1<10 Mpc
n
ECMBR ~ 6.6·10-4 eV E ~ 1013.5 eV
Lower energy photons interact also with IR backgrond
2 2N
p
m mE E
2
See also T. Stanev,2004 for p-IR interactions
E. Migneco Erice ISCRA, July 2-13 2004
The GZK effect
Closest AGNs
Galactic radius (15 kpc)
5 Gpc
E. Migneco Erice ISCRA, July 2-13 2004
High Energy neutrinos production
Are the astrophysical sources of High Energy
CR also candidate sources of HE neutrinos ?
The interaction of protons with ambient gas or
photon field may produce neutrino fluxes
Are the astrophysical sources of High Energy
CR also candidate sources of HE neutrinos ?
The interaction of protons with ambient gas or
photon field may produce neutrino fluxes
E. Migneco Erice ISCRA, July 2-13 2004
Neutrino production in cosmic accelerators
Halzen
Proton acceleration
• Fermi mechanism
proton spectrum dNp/dE ~E-2
Neutrino production
• Proton interactions
p p (SNR,X-Ray Binaries)
p (AGN, GRB, microQSO)
• decay of pions and muons
Astrophysical jet
Particle accelerator
electrons are responsible for gamma fluxes (synchrotron, IC)
E. Migneco Erice ISCRA, July 2-13 2004
HE proton interaction on ambient p or
Beam dump in SNR environment
0
CANGAROO observationsof RXJ1713.7-3946 fit with TeV gamma ray production by 0 decay (?)
+
-
Muons and muon-neutrinos
Beam dump in astrophysical jet environment (GRB,AGN,microQSO)
p n
Shock waves
Matter shells
HE proton
Target photons
pions
1
muons and neutrinos
2 2
N
N
m mE 0.34 GeV
2m
p0.05
HE proton
SN shells,clouds,..
Shock wave
Target protons
E. Migneco Erice ISCRA, July 2-13 2004
Neutrino fluxes chemical composition
ee
If the muon interaction time (IC) is larger than the muon decay time
electron neutrinos and antineutrinos are also produced
ee
Tau neutrinos are unlikely produced in the sources (M = 1.7 GeV)
They can be detected at the Earth as “oscillated” muon neutrinos:
2 2 2
162 3
3
L kmP sin 1.27 m eV
E GeV
10 L kpc 1P sin 10
10 E TeV 2
e: : 1:1:1
E. Migneco Erice ISCRA, July 2-13 2004
Limits of HE gamma and proton astronomy
High energy protons 50 Mpc
neutrinos
Astrophysicalsource
Low energy protons deflected
High energy gammas 10 Mpc
E. Migneco Erice ISCRA, July 2-13 2004
Motivations of high energy neutrino astronomy
Extend the high energy CR and Horizon (<50 Mpc)
Identify the sources of UHE particles
Explore deep inside the source (where »1 for CR and )
Probe hadronic models in astrophysical sources
Extend the high energy CR and Horizon (<50 Mpc)
Identify the sources of UHE particles
Explore deep inside the source (where »1 for CR and )
Probe hadronic models in astrophysical sources
E. Migneco Erice ISCRA, July 2-13 2004
High energy neutrino fluxes
Astrophysical sources are expected to produce a
diffuse high energy neutrino flux with spectral index 2
The most powerful and/or the closest sources could
give a clear point-like neutrino signal
Time correlations between events and photons will be
clear signatures for transient source detection
Astrophysical sources are expected to produce a
diffuse high energy neutrino flux with spectral index 2
The most powerful and/or the closest sources could
give a clear point-like neutrino signal
Time correlations between events and photons will be
clear signatures for transient source detection
E. Migneco Erice ISCRA, July 2-13 2004
The WB bound
The WB bound is valid for:
• Sources optically thin to UHECR (responsible for the observed spectrum)
• Sources in which CR acceleration takes place (top-down excluded)
“thick sources”
p 1
p 1 “thin sources”
atmo
sph
ericWaxman Mannheim
An upper limit to the diffuse neutrino flux was set by Waxman and Bahcall
assuming that the detected UHECR sources are the only neutrino sources
MPR bound
WB bound
GeV
E. Migneco Erice ISCRA, July 2-13 2004
Possible extragalactic sources and fluxes
Learned Mannheim
AGNGZK
p AGN corespp AGN cores
p blazar
GRB
WB Limit
Diffuse neutrino fluxes
Bright and nearby GRB could produce intense directional fluxes (e.g. GRB
030329) as well as brightest AGNs (3C273, 3C279)
Stecker
Nellen
Mannheim
Bierman
Waxman
Ruled out by
new AMANDA data
(preliminary)
E. Migneco Erice ISCRA, July 2-13 2004
Galactic Sources of HE neutrinos
Galactic sources do not contribute to UHECR fluxes, therefore are not limited
by WB bound. Even if much less intense, their proximity to the Earth may yield
detectable neutrino fluxes
Another important source of TeV neutrinos could be the Galactic centre
(SGR-A*) which is a very active gamma source
SNR, extensively discussed:(see T. Stanev)
2 112
ergE 10
cm s
CRAB, Protheroe
2 9 112
ergE 10 10
cm s
microquasarMost powerful GX339-4 SS433
Distefano
E. Migneco Erice ISCRA, July 2-13 2004
High energy neutrino detection
Detection of HE astrophysical neutrinos is achieved
through CC neutrino interaction with matter with
charged lepton production
Neutrino astronomy requires reconstruction of
direction and energy of the reaction products
(charged leptons)
Detection of HE astrophysical neutrinos is achieved
through CC neutrino interaction with matter with
charged lepton production
Neutrino astronomy requires reconstruction of
direction and energy of the reaction products
(charged leptons)
E. Migneco Erice ISCRA, July 2-13 2004
Neutrino cross section
N X
Neutrinos are detected indirectly,
following a DIS on a target
nucleus N:
1 TeV 1 PeV
1.5
E TeV
X
N
At >TeV energies the muon and the neutrino are co-linear
Reconstruction of the trajectory allows the identification of the direction
N0.4
E E 5TeV
E E 5TeV
Gandhi
10-33 cm2
10-35cm2
E. Migneco Erice ISCRA, July 2-13 2004
Muon Range
E(GeV)R
ang
e (m
)
Muons have long tracks in water
2
24
dEa b E
dx
GeVcma 0.2
g
cmb 4
1R ln a bE
b
10g
Due to its larger mass (m/ me~200) radiative losses of muons are
strongly suppressed with respect to electrons
R E 300GeV 1 km
Gaisser
1 TeV 1 PeV
2·103
2·104
In w
ater
E. Migneco Erice ISCRA, July 2-13 2004
Muon vs electron range
Spiering Wiebush
Electron
Muon 100 TeV
1 TeV
100 GeV 10 GeVGeant 3.21
E. Migneco Erice ISCRA, July 2-13 2004
Neutrino detection probabilty
6 2.2 3
6 0.8 3 6
1.3 10 E 1 10 GeV
1.3 10 E 10 10 GeV
,min
CC 'E Nmin ' min '
A eff'E
d E ,EP E ,E N dE R E ,E
dE
Instrumented detector D<R
Due to the long muon range the target volume is much bigger than the
detector instrumented volume
Probabilty to produce a detectable (E>Emin) muon
E. Migneco Erice ISCRA, July 2-13 2004
P
·10-3
LogE(GeV)
,minE 1TeV
E,min=1GeV
• Probabilty to produce a detectable (E>Emin) muon
tot A
,min
E,min E N Z
,minE
N E ,dE E , P E ,E e
AT
Neutrino-induced muon fluxes
deg
PE
arth
100 TeV
10 TeV
1 TeV
• Earth transparency to HE neutrinos >PeV neutrinos search for “horizontal” tracks
The number of muon events in units of detection area A and observation time T is:
• Neutrino flux spectrum
E. Migneco Erice ISCRA, July 2-13 2004
Detection area for astrophysical UHE neutrino fluxes
2 82
GeV4.5 10
cm s sr
The observation of TeV
neutrino fluxes
requires km2 scale
detectors
2
84 10 7
y5 kmE 100TeV
2
E 100TeV
4.5 10N 10 10 A 3 10 T 2
10
N 70 AT km y
The expected number of events for WB sources is roughly:
E. Migneco Erice ISCRA, July 2-13 2004
Expected astrophysical neutrino induced muons in 1 km2
DiffuseGuaranteed (GZK): few / year ?
Diffuse GRB: 20 / year
Diffuse AGN (thin): few / year
(thick): >100 / year
Point-likeGRB (030329): 110 / burst
AGN (3C279): few / year
Galactic SNR (Crab): few / year ?
Galactic microquasars: 1 100 / year
Waxman
Waxman
Dermer
Distefano
Mannheim
Protheroe
E. Migneco Erice ISCRA, July 2-13 2004
km3 scale neutrino detectors
The requirement of large neutrino interaction target
induced Markov and Zheleznykh to propose the use
of natural targets.
Deep seawater and polar ice offers:
• huge (and inexpensive) target for neutrino interaction;
• good optical characteristics as Cherenkov radiators;
• shielding from cosmic background.
The requirement of large neutrino interaction target
induced Markov and Zheleznykh to propose the use
of natural targets.
Deep seawater and polar ice offers:
• huge (and inexpensive) target for neutrino interaction;
• good optical characteristics as Cherenkov radiators;
• shielding from cosmic background.
E. Migneco Erice ISCRA, July 2-13 2004
Underwater Cherenkov detectors: detection principles
neutrino
muon
Cherenkov light
~5000 PMT
Connection to the shore
neutrino
atmospheric muon
depth>3000m
E. Migneco Erice ISCRA, July 2-13 2004
The km3 telescope: a downward looking detector
Neutrino telescopes search for muon tracks induced by neutrino interactions
The downgoing atmospheric flux overcomes by several orders of
magnitude the expected fluxes induced by interactions.
On the other hand, muons cannot
travel in rock or water more than
50 km at any energy
Upgoing and horizontal muon
tracks are neutrino signatures
E. Migneco Erice ISCRA, July 2-13 2004
Cherenkov light emission and propagation
2n 1
700nm
300nm
dN 2 1 1 1 -
dx c n
dN photons300
dx cm
The Cherenkov light is efficiently emitted by relativistic particles in water
at UV-blue wavelengths under the condition: n() > 1
Superkamiokande muon event
C ~ 42°
n (300700nm) ~ 1.35
E. Migneco Erice ISCRA, July 2-13 2004
Cherenkov track reconstruction
pseudo vertex
j 0 j j cc(t - t ) = l + d ctg( )
De Jong
Cherenkov photons emitted by the
muon track are correlated by the
causality relation:
The track can be reconstructed
during offline analysis of space-
time correlated PMT signals (hits).
E. Migneco Erice ISCRA, July 2-13 2004
Detector granularity
a
D0
a
I I e
L blue 70m
Spacing of optical sensors inside the instrumented volume must be of the order of the light absorption lenght in water (70 m for blue light)
About 5000 optical sensors are needed to fill up one km3
Visible light
E. Migneco Erice ISCRA, July 2-13 2004
Backgrounds
Neutrino detectors must identify few astrophysical
events on top of diffuse atmospheric backgrounds
Neutrino detectors must identify few astrophysical
events on top of diffuse atmospheric backgrounds
E. Migneco Erice ISCRA, July 2-13 2004
Backgrounds: atmospheric muons and neutrinos
Atmospheric neutrinos:
• upward tracks are good neutrino candidates; • event direction and energy criteria can be used to discriminate background from astrophysical signals.
Atmospheric muons:
• downgoing events background is due to mis-reconstructed (fake) tracks;
• improve analysis filters for atmospheric muon background rejection.
ANTARES
E. Migneco Erice ISCRA, July 2-13 2004
Atmospheric muon background vs depth
Downgoing muon background is
strongly reduced as a function of
detector installation depth.
Depth >3000 m (1 km rock) is
suggested for detector installation
NEMO
NESTOR
ANTARESAMANDA
Bugaev
BAIKAL
E. Migneco Erice ISCRA, July 2-13 2004
First detection of HE neutrino events
Proof of the underwater (and underice) Cherenkov
detection technique has been achieved by AMANDA
(South Pole) and BAIKAL-NT (Lake Baikal) detectors
Proof of the underwater (and underice) Cherenkov
detection technique has been achieved by AMANDA
(South Pole) and BAIKAL-NT (Lake Baikal) detectors
E. Migneco Erice ISCRA, July 2-13 2004
The AMANDA neutrino sky
AMANDA and BAIKAL have demontrated the viability of neutrino detection with underwater and underice Cherenkov detectors at TeV energy scale
AMANDA PRELIMINARY
(neutrino 2004 conference)
The atmospheric neutrino spectrum has been measured by AMANDA and BAIKAL
See Silvestri’s talk
E. Migneco Erice ISCRA, July 2-13 2004
The future neutrino telescopes
The quest to reach the km2 effective area is open !
Southern Hemisphere ICECUBE
Northern HemisphereMediterranean km3
1400 m
2400 m
IceTop
>3000 m
E. Migneco Erice ISCRA, July 2-13 2004
Summary
• High energy astrophysical neutrino fluxes are expected on the
base of CR and observations
• Neutrino detection will provide unique informations on
astrophysical sources:
overcomes the limitations of and CR astronomy due to
absorption on CMBR at cosmological distances;
evidence on the role of hadronic processeses in
astrophysics
• Neutrino events correlated in space and time with point-like
(transient) sources will be probably the first evidence of detection
of astrophysical neutrinos
• The expected fluxes from sources implies >1km2 effective area to
detect TeV-PeV neutrinos
• High energy astrophysical neutrino fluxes are expected on the
base of CR and observations
• Neutrino detection will provide unique informations on
astrophysical sources:
overcomes the limitations of and CR astronomy due to
absorption on CMBR at cosmological distances;
evidence on the role of hadronic processeses in
astrophysics
• Neutrino events correlated in space and time with point-like
(transient) sources will be probably the first evidence of detection
of astrophysical neutrinos
• The expected fluxes from sources implies >1km2 effective area to
detect TeV-PeV neutrinos
E. Migneco Erice ISCRA, July 2-13 2004
Other scientific goals
Galactic SN:
search for intense fluxes of electron anti-neutrinos
need low optical background task for AMANDA-ICECUBE
Dark Matter:
search for neutrinos ( 10 GeV) originated by the
annihilation of neutralinos in the Sun, Earth, Galactic Centre
low energy threshold, good event direction reconstruction
Galactic SN:
search for intense fluxes of electron anti-neutrinos
need low optical background task for AMANDA-ICECUBE
Dark Matter:
search for neutrinos ( 10 GeV) originated by the
annihilation of neutralinos in the Sun, Earth, Galactic Centre
low energy threshold, good event direction reconstruction