Neutrino astronomy and telescopes

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


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


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%


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


The challengeThe challenge

We learned:

Weak interactions make neutrinos excellent probes of the universe but their detection is difficult !


Neutrino FluxesNeutrino Fluxes

Atmospheric ss from WIMP annhilationCosmic s


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?


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


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


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


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


~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


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


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)


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)


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)


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


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


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)


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


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


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!


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


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


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


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

Neutrino astronomy and telescopes

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