Neutrino astronomy and telescopes
Teresa Montaruli, Assistant Professor, Chamberlin Hall, room 5287, [email protected]
Crab nebulaCrab nebula
Cen ACen A
Teresa Montaruli, 5 - 7 Apr. 2005Teresa Montaruli, 5 - 7 Apr. 2005
OverviewOverviewNeutrinos and their properties
Neutrino astronomy and connections to Cosmic rays and gamma-astronomy
Neutrino sources and neutrino production
Neutrino telescopes
Search Methods
The Cherenkov technique and the photosensors
Current experimental scenario
Teresa Montaruli, 5 - 7 Apr. 2005Teresa Montaruli, 5 - 7 Apr. 2005
Some neutrino hystorySome neutrino hystory• 4 Dec 1930: W. Pauli pioneering hypothesis on neutrino existence as a “desperate remedy” to explain the continuous -decay energy spectrum Dear radioactive ladies and gentlemen,As the bearer of these lines, to whom I ask you to listen graciously, will explain more exactly, considering the ‘false’ statistics of N-14 and Li-6 nuclei, as well as the the desperate remedy……Unfortunately, I cannot personally appear in Tübingen, since I am indispensable hereon account of a ball taking place in Zürich in the night from 6 to 7 of December….
• 1933 E. Fermi : -decay theory
Week interactions: GWeek interactions: GFF << << of of electromagnetic interactionselectromagnetic interactions
• 1956 Cowan and Reines : first detection of reactor neutrinosby simultaneous detection of 2‘s from e+ pair annihilation andneutronneutron
Teresa Montaruli, 5 - 7 Apr. 2005Teresa Montaruli, 5 - 7 Apr. 2005
Astrophysical neutrinos: from Astrophysical neutrinos: from the Sunthe Sun
Pioneer experiment: 1966 R. Davis in Homestake MineRadiochemical experiment: 615 tons of liquid perchloroethylene (C2Cl4), reaction e + 37Cl -> e- + 37Ar, Eth=0.814 MeV, operated continuously since 1970 Observed event rate of 2.56±0.23 SNU (1 SNU =10-36 interactions per target atom per second) Standard Solar Model prediction: 7.7+1.2-1.0 SNU Solar neutrino problem, now solved by oscillations
Combined effect of nuclear fusion reactions
Predicted fluxes from Standard Solar ModelUncertainty ~ 0.1%
Teresa Montaruli, 5 - 7 Apr. 2005Teresa Montaruli, 5 - 7 Apr. 2005
Astrophysical neutrinos: from SN1987AAstrophysical neutrinos: from SN1987A
http://www.nu.to.infn.it/Supernova_Neutrinos/#7
enpe
• SN1987A:SN1987A: 99% of binding energy in s in a core collapse SN Neutronization, ~10 ms 1051 ergThermalization: ~10 s 31053 erg
enpe
ee
Teresa Montaruli, 5 - 7 Apr. 2005Teresa Montaruli, 5 - 7 Apr. 2005
The challengeThe challenge
We learned:
Weak interactions make neutrinos excellent probes of the universe but their detection is difficult !
Teresa Montaruli, 5 - 7 Apr. 2005Teresa Montaruli, 5 - 7 Apr. 2005
Neutrino FluxesNeutrino Fluxes
Atmospheric ss from WIMP annhilationCosmic s
Teresa Montaruli, 5 - 7 Apr. 2005Teresa Montaruli, 5 - 7 Apr. 2005
Why neutrinos are interesting?Why neutrinos are interesting? After photons (400 After photons (400 /cm/cm33) is the most abundant element from ) is the most abundant element from
the Big Bang in the Universe (nthe Big Bang in the Universe (n ~~3/11n3/11n)) Open questions: mass? Majorana or Dirac?Open questions: mass? Majorana or Dirac? Leptons and quarks in Standard Model are Dirac particles: Leptons and quarks in Standard Model are Dirac particles:
particles differ from antiparticles, 2 helicity statesparticles differ from antiparticles, 2 helicity states In the Standard Model the In the Standard Model the is massless and neutral and only is massless and neutral and only LL and and RR. .
It is possible to extend the SM to have massive neutrinos and they may be It is possible to extend the SM to have massive neutrinos and they may be Majorana particles (particle=antiparticle) if only Majorana particles (particle=antiparticle) if only LL ad ad RR exist exist
The mass is a fundamental constant: needs to be measured!! The mass is a fundamental constant: needs to be measured!! Direct neutrino mass measurements
e< 3 eV ~ 3 x 10-9 mproton from decay of 3H (Z,A)(Z+1,A) + e- + e
µ< 0.17 MeV ~ 2 x 10-4 mproton from
< 18.2 MeV ~ 2 x 10-2 mproton from 5
Neutrino mass =0?
Teresa Montaruli, 5 - 7 Apr. 2005Teresa Montaruli, 5 - 7 Apr. 2005
Neutrino properties: oscillations Neutrino properties: oscillations
i
iiU ,
ji
ELmijjii
jieUUUUP,
2,
*,
*,,
2,
A A created in a leptonic decay of defined flavor is a linear superposition of mass created in a leptonic decay of defined flavor is a linear superposition of mass eigenstateseigenstates
Given a neutrino beam of a given momentum the various mass states have different energies and after a time t the probability that another flavor appears is
22ii mpE
iii
tiE Uet i ,)(
where p
mpE2
2
L=baselineFor 2 flavor:
cossinsincos
U
)()()(27.1sin2sin
2222
GeVEkmLeVmP
Though oscillations are an indirect way of measuring the mass that requires many different experiments to reach an understanding of the difference of the square masses and of the flavors involved, they have the merit of beingsensitive to very small masses m2~<E>/L depending on the experiment design
Teresa Montaruli, 5 - 7 Apr. 2005Teresa Montaruli, 5 - 7 Apr. 2005
The experimental scenarioThe experimental scenario
SNO at Sudbury MineSNO at Sudbury Mine
Recent atmospheric neutrino experiments (Super-Kamiokande, MACRO, Soudan 2) have demonstrated that the deficit is due to oscillations with maximal mixing matm
2 ~ 2.5 · 10-3 eV2 sin22 ~ 1
Solar neutrino experiments: (Cherenkov detectors: Super-Kamiokande, SNO)+KAMLAND: scintillator detector looking for e from reactors at ~180 kmaverage distance) deficit compatible with msun
2 ~ 7.1 · 10-5 eV2 sin22 ~ 0.82, could be due to e or e
Reactor neutrino experiments L~1 km (CHOOZ) constrain the 13 mixing (no disappearance)
33
2211
Teresa Montaruli, 5 - 7 Apr. 2005Teresa Montaruli, 5 - 7 Apr. 2005
Astronomy with particlesAstronomy with particles straight line propagation to point back to sources Photons: reprocessed in sources and absorbed by extragalactic
backgrounds For E > 500 TeV do not survive journey from Galactic Centre Protons: directions scrambled by galactic and intergalactic magnetic fields
(deflections <1° for E>50 EeV)
Interaction length pp + + CMBCMB + n + n pp = = ( n( nCMBCMB ) ) -1-1 ~~ 10 Mpc10 Mpc Neutrons: decay ct E/mn ct ~10kpc for E~EeV
eVEnGB
Mpcd
EdB
Rd
gyro20103
111.0 d
Rgyro
evB = mv2/Rgyro eB = p/Rgyro 1/Rgyro = B/E
Teresa Montaruli, 5 - 7 Apr. 2005Teresa Montaruli, 5 - 7 Apr. 2005
p
Messengers from the Universe
Photons currently Photons currently provide all provide all informationinformationon the Universe buton the Universe butinteract in sources interact in sources and during and during propagationpropagationNeutrinos andNeutrinos andgravitational wavesgravitational waveshave discovery have discovery potential becausepotential becausethey open a newthey open a newwindow on the window on the universeuniverse
pee p + + n
+radio
+IRe+e-
+MW
Local Group
3C279
Mrk421
Gal Cen <100 Mpc 1-10<100 Mpc 1-1099 TeV TeV
W49B
SN 0540-69.3
Crab
E0102-72.3
Cas A
1 pc ~ 3 ly ~ 101 pc ~ 3 ly ~ 101818 cm cm
Teresa Montaruli, 5 - 7 Apr. 2005Teresa Montaruli, 5 - 7 Apr. 2005
~E-3.1
~E-2.7
~E-2.7
After T. Gaisser, ICHEP02
106 eV to ~1020 eV
BalloonsBalloonssatellitessatellites EASEAS
kneeknee
Ankle: Ankle: 1 km1 km-2-2 century century-1-1
The CR spectrumThe CR spectrumSN provide right power for galactic CRs up to the knee:CR energy density: E~ 1 eV/cm3 ~ B2
galactic / 8 Needed power: E / esc ~10-26 erg/cm3s with galactic escape time esc ~ 3 x 106 yrs SN power: 1051 erg/SN + ~3 SN per century in disk ~ 10-25 erg/cm3s 10% of kinetic energy in proton and nuclei acceleration
Teresa Montaruli, 5 - 7 Apr. 2005Teresa Montaruli, 5 - 7 Apr. 2005
Hillas Plot
R = acceleration site dimensions
eVkpcR
GBZE 18
max 1011
CR acceleration at sourcesCR acceleration at sources
energy losses in sources neglected
The accelerator sizemust be larger than Rgyro
Teresa Montaruli, 5 - 7 Apr. 2005Teresa Montaruli, 5 - 7 Apr. 2005
The kneeThe knee
Modest improvements in hadronic interaction models due to large uncertainties (different kinematic region than colliders) + stochastic nature of hadronic interactions large fluctuations in EAS measurements
Kascade - QGSJETKascade - QGSJET
What is the origin of the knee?What is the origin of the knee?1.1. Acceleration cutoff Acceleration cutoff Emax~ZBL~Zx100TeV, change in acceleration
process?2.2. Confinement in the galactic magnetic field: rigidity dependent Confinement in the galactic magnetic field: rigidity dependent
cut-offcut-off3.3. Change in interaction properties (eg. onset of channel where Change in interaction properties (eg. onset of channel where
energy goes into unseen particles)energy goes into unseen particles)
Teresa Montaruli, 5 - 7 Apr. 2005Teresa Montaruli, 5 - 7 Apr. 2005
The ankle: the EHE regionThe ankle: the EHE region
Ankle: E-2.7 at E~1019 eV could suggest a new light population Protons are favored by all experiments.
• What is the acceleration mechanism at these energies? • Which are the sources? Are there extra-galactic components?• Which particles do we observe?• Is there the expected GZK “cutoff”?
AGASA: 111 AGASA: 111 scintillators +
27detectors
Fe frac. (@90% CL): < 35% (1019 –1019.5 eV), < 76% (E>1019.5eV)Gamma-ray fraction upper limits(@90%CL) 34% (>1019eV) (/p<0.45) 56% (>1019.5eV) (/p<1.27)
Teresa Montaruli, 5 - 7 Apr. 2005Teresa Montaruli, 5 - 7 Apr. 2005
Relativity: 4-vectorsRelativity: 4-vectors
Covariant pCovariant p = (E/c,-p = (E/c,-pxx,-p,-py-y-ppzz))Scalar product of 2 4-vectorsScalar product of 2 4-vectorsqqkk = (E = (EqqEEkk/c/c22-p-pqxqxppkxkx-p-pqyqyppqyqy-p-pqzqzppqzqz))SquareSquarepp22 = (E/c) = (E/c)2 2 - p- p22 = m = m22 = constant = constant
Also:Also:
2
2
11
/v
v
ccmE
mp
Transform from one coordinate system to anotherTransform from one coordinate system to anothermoving with speed moving with speed vv in the x direction (Lorentz in the x direction (Lorentztransformation)transformation)
p’p’xx = = (p(pxx – – E/c) E/c) p’p’yy = p = pyy p’p’zz = p = pzz E’ = E’ = (E – (E – ppxxc) c)
z
y
x
z
y
x
pppcE
pppcE /
100001000000
'''/'
In general: (E*,p*) in a frame moving at velocity f:
||=parallel to direction of motionT=transverse
Controvariant pControvariant p = (E/c,p = (E/c,pxx,p,pyyppzz)=(E/c,p))=(E/c,p)
Teresa Montaruli, 5 - 7 Apr. 2005Teresa Montaruli, 5 - 7 Apr. 2005
Reaction ThresholdsReaction Thresholdsmmt,t,pppp mmtt,p,ptt
22
21 ...
tottotf
f
f
pEMs
MMMpt
True in any reference systemTrue in any reference system
In the labIn the lab
s = Es = Ecmcm22 c= 1 c= 1
ptot
pkpttot
pp
EmmE
,
mmpp mmt at restt at rest
t
ptf
f
pk
pktpkptf
f
ppkptpkptf
f
ppkptf
f
m
mmME
EmEmmM
pEmmEmmM
pEmmM
2
)(
2)(
)(2)(
)(
2
2
,
,2,
2
2
2,
2,
2
2
22,
2
2222
22
2 mpmEmE
mpmEE
kinkin
kintot
2,
2,2 pkpkp EpEm
Energy of projectileEnergy of projectileto produce particlesto produce particlesin the final statein the final stateat restat rest
Teresa Montaruli, 5 - 7 Apr. 2005Teresa Montaruli, 5 - 7 Apr. 2005
Threshold for GZK cut-offThreshold for GZK cut-off [Greisen 66; Zatsepin & Kuzmin66]
Integrating over Planck spectrum Ep,th~ 5 ·1019 eV
np
pp 0
Threshold pr p-N
MeV150
MeV145
E
E
=3k=3kBBT effective energy for Planck spectrumT effective energy for Planck spectrum
2.73 K2.73 Kp
pN
t
ptf
f
pk mmmm
m
mmME
2)(
2
)( 222
2
,
Energy of CMB photons: Energy of CMB photons:
in frame where p is at restin frame where p is at rest
And their energy in the proton rest frame isAnd their energy in the proton rest frame is
MeV150 pE pp= 2= 2·· 10 1011 11 and the threshold and the threshold energy of the proton is then energy of the proton is then EEpp = = pp m mpp = 2 = 2 ··10102020 eV eV
Teresa Montaruli, 5 - 7 Apr. 2005Teresa Montaruli, 5 - 7 Apr. 2005
GZK cut-off?GZK cut-off?AGASA: 11 events, expects 2 @ E> 10AGASA: 11 events, expects 2 @ E> 102020 eV eV44 from GZK model from uniform distribution from GZK model from uniform distribution of sourcesof sourcesHires (fluorescence technique) compatible Hires (fluorescence technique) compatible at 2at 2Uncertainties on E Uncertainties on E ~30%~30%Not enough statistics to solve the Not enough statistics to solve the controversycontroversyAGASA anisotropies: E>4 ·10AGASA anisotropies: E>4 ·101919 eV eV
[Greisen 66; Zatsepin & Kuzmin66]
Air fluorescence detectors HiRes 1 - 21 mirrors HiRes 2 - 42 mirrors Dugway (Utah)
Teresa Montaruli, 5 - 7 Apr. 2005Teresa Montaruli, 5 - 7 Apr. 2005
AnistropiesAnistropiesGalaxy cannot contain EHECR: at 1019 eV Larmour radius of CR p comparable to Galaxy scale AGASA: E>4 ·1019 eV no evidence of anisotropies due to galactic disc but large scale isotropy EHECR are extra-galacticAGASA : 67 events cluster 1 triplet (chance prob <1%) + 9 doublets (expect 1.7 chance probability <0.1%) at small scale (<2.5˚) Not confirmed by HiRES
TripletTripletclose toclose tosuper-galactic super-galactic planeplaneSee alsoSee alsoUHECR UHECR correlation with correlation with super-galactic super-galactic planeplaneastro-ph/9505093 astro-ph/9505093
Teresa Montaruli, 5 - 7 Apr. 2005Teresa Montaruli, 5 - 7 Apr. 2005
Neutrino production: bottom upNeutrino production: bottom up
Neglecting absorption (uncertain) Targets: p or ambient
Beam-dump model: 0 -astronomy ± -astronomy
0
p
ee
e
Berezinsky et al, 1985Gaisser, Stanev, 1985
Teresa Montaruli, 5 - 7 Apr. 2005Teresa Montaruli, 5 - 7 Apr. 2005
From photon fluxes to From photon fluxes to predictions:pp predictions:pp
dEdEdNEKdE
dEdN
EE
E
E
E max
min
max
min
K = 1 ppK = 1 pp
3pEE
62pEEE
124pEEE
2 photons with
2 and 1 e with
Minimum proton energy fixed by threshold for production ( =E/m is the Lorentz factor of the p jet respect to the observer)
The energy imported by a in decay is ¼ E
K = 1 since energy in photons K = 1 since energy in photons matches that in matches that in ss22s with Es with Epp/12 for each /12 for each E Epp/6/6
nppp
pppp 0
Exercises!Exercises!
Teresa Montaruli, 5 - 7 Apr. 2005Teresa Montaruli, 5 - 7 Apr. 2005
From photon fluxes to From photon fluxes to predictions: p predictions: p
dEdEdNEKdE
dEdN
EE
E
E
E max
min
max
minK = 4 pK = 4 p
ppp ExE
E %102
ppp ExE
E %54
2.0 px
np
pp
)2
)1 0BR = 2/3BR = 2/3BR = 1/3BR = 1/3
1) 21) 2s with 2/3s with 2/3× × EE = 2/3 = 2/3 ··0.1E0.1Epp
2) 22) 2s with 1/3s with 1/3× × EE = 1/3 0.1 = 1/3 0.1··EEpp /2 /2K = 4K = 4
Teresa Montaruli, 5 - 7 Apr. 2005Teresa Montaruli, 5 - 7 Apr. 2005
22ndnd order Fermi acceleration (1 order Fermi acceleration (1stst version 1949) version 1949)Magnetic clouds in interstellar medium moving at velocity V (that remains unchanged after the collision with a relativistc particle particle v~c) The probability of head-on encounters is slightly greater than following collisionsVV VV
Head-on Following
This results in a net energy gain per collision of
vv
2
34
cV
EE
2nd order in the velocity of the cloud
Magnetic Cloud
Magnetic inhomogenities
Teresa Montaruli, 5 - 7 Apr. 2005Teresa Montaruli, 5 - 7 Apr. 2005
CasA Supernova Remnant in X-rays
John Hughes, Rutgers, NASA
Shock fronts
11stst order Fermi acceleration order Fermi accelerationThe 2nd order mechanism is a slow process. The 1st order is more efficient since only head-on collisions in shock waves
High energy particles upstream and downstream of the shock obtain a net energy gain when crossingthe shock front in a round trip
cV
EE
34 1nd order in the velocity of
the shock
Equation of continuity: 1v1=2v2
For ionized gas 1/2 = 4 v2 =4 v1
v2=u
Shock front at rest: upstream gas flows into shock at v2 =uAnd leaves the shock with v1 = u/4
v1=u/4<v2
Interstellar mediumBlast shock Blast shock
Magnetic Inhomogenities
vv22>v>v11
upstreamupstream
downstreamdownstream
Teresa Montaruli, 5 - 7 Apr. 2005Teresa Montaruli, 5 - 7 Apr. 2005
Fermi mechanism and power lawsFermi mechanism and power lawsE = E0 = average energy of particle after collision P = probability of crossing shock again or that particle remains in acceleration region after a collisionAfter k collisions: E = kE0 and N = N0Pk = number of particles
Naturally predicts
CRs have steeper spectrum due to energy dependence of diffusion in the Galaxy
c
cP
dEEdNEE
NN
PNN
EE
kP
P
12
1
1logloglog
log
00
00
vv
v1
log
log
log
log
Particles lost in each round trip on the shockParticles lost in each round trip on the shock
1v/v1
13vv
v3loglog
1221
1
P
7.2 EdEdN
2 EdEdN
v1 velocity of gasleaving the shockv2 velocity of gasflowing into shock