Neutrinos – Ghost Particles of the Universe

Georg Raffelt, MPI Physics, Munich 1st Schrödinger Lecture, University Vienna, 5 May 2011

Neutrinos – Ghost Particles of the UniverseNeutrinos

Ghost Particles of the Universe

Georg G. RaffeltMax-Planck-Institut für Physik, München, Germany


Neutron

ProtonGravitation (Gravitons?)

Weak Interaction (W and Z Bosons)

Periodic System of Elementary Particles

Electromagnetic Interaction (Photon)

Strong Interaction (8 Gluons)

Down

Strange

Bottom

Electron

Muon

Tau

e-Neutrino

m-Neutrino

t-Neutrino nt

nm

nee

m

t

d

s

b

1st Family

2nd Family

3rd Family

Up

Charm

Top

u

c

t

Quarks Leptons

Charge -1/3

Down

Charge -1

Electron

Charge 0

e-Neutrino need

Charge +2/3

Up u

Where do Neutrinos Appear in Nature?

Nuclear Reactors

Particle Accelerators

Earth Atmosphere(Cosmic Rays)

Earth Crust(Natural Radioactivity)

AstrophysicalAccelerators Soon ?

Sun

Supernovae(Stellar Collapse) SN 1987A

Cosmic Big Bang (Today 330 n/cm3) Indirect Evidence


Pauli’s Explanation of the Beta Decay Spectrum (1930)

Niels Bohr:Energy notconserved inthe quantumdomain?“Neutron”

(1930)Wolfgang Pauli(1900–1958)Nobel Prize 1945

“Neutron”(1930)

“Neutrino”(E. Fermi)


Neutrinos from the Sun

Reaction-chains

Energy26.7 MeV

Helium

Solar radiation: 98 % light 2 % neutrinosAt Earth 66 billion neutrinos/cm2 sec

Hans Bethe (1906-2005, Nobel prize 1967)Thermonuclear reaction chains (1938)


Sun Glasses for Neutrinos?

8.3 light minutes

Several light years of lead needed to shield solar neutrinos

Bethe & Peierls 1934: … this evidently means that one will never be able to observe a neutrino.


First Detection (1954 – 1956)

Fred Reines(1918 – 1998)Nobel prize 1995

Clyde Cowan(1919 – 1974)

Detector prototype

Anti-Electron Neutrinosfrom Hanford Nuclear Reactor

3 Gammasin coincidence𝝂𝐞 p

n Cd

e+¿ ¿ e−

g

g

g


First Measurement of Solar Neutrinos

600 tons ofPerchloroethylene

Homestake solar neutrino observatory (1967–2002)

Inverse beta decayof chlorine

Cherenkov Effect

Water

Elastic scattering or CC reaction

NeutrinoLight

Light

Cherenkov Ring

Electron or Muon(Charged Particle)


Super-Kamiokande Neutrino Detector (Since 1996)

42 m

39.3 m

Super-Kamiokande: Sun in the Light of Neutrinos


Neutrino Flavor Oscillations

Bruno Pontecorvo(1913–1993)

Invented nu oscillations

Two-flavor mixing

Each mass eigenstate propagates as with Phase difference implies flavor oscillations

Oscillation Length

sin 2(2𝜃)Probability

z

(𝜈𝑒

𝜈𝜇)=(c os𝜃 sin𝜃− sin 𝜃 c os 𝜃)(𝜈1𝜈2)

4𝜋 𝐸𝛿𝑚2 =2.5 m

𝐸MeV (eV𝛿𝑚

2

)


• Japanese Nuclear Reactors 80 GW (20% world capacity)• Average distance 180 km• Flux 6 105 cm-2 s-1 • Without oscillations 2 captures per day

KamLAND Long-Baseline Reactor-Neutrino Experiment


Oscillation of Reactor Neutrinos at KamLAND (Japan)Oscillation pattern for anti-electron neutrinos from

Japanese power reactors as a function of L/E

KamLAND Scintillatordetector (1000 t)


Atmospheric Neutrino AnomalyZenith-angle distribution of atmospheric neutrinosin Super-Kamiokande [hep-ex/0210019]

Half of the muon neutrinosfrom below are missing


Long-Baseline Experiment K2K

K2K Experiment(KEK to Kamiokande)has confirmedneutrinooscillations,to be followedby T2K (2010)


Current Long-Baseline ExperimentsFermiLab–Soudan (MINOS) CERN – Gran Sasso


v

v

Three-Flavor Neutrino Parameters

(𝜈𝑒𝜈𝜇

𝜈𝜏)=(1 0 00 𝑐23 𝑠230 −𝑠23 𝑐23)(

𝑐13 0 𝑒−𝑖 𝛿𝑠130 1 0

−𝑒𝑖𝛿 𝑠13 0 𝑐13 )( 𝑐12 𝑠12 0−𝑠12 𝑐12 00 0 1)(

1 0 0

0 𝑒𝑖𝛼2

2 0

0 0 𝑒𝑖 𝛼3

2 )(𝜈1𝜈2𝜈3)Three mixing angles , , (Euler angles for 3D rotation), ,a CP-violating “Dirac phase” , and two “Majorana phases” and

⏟⏟⏟⏟39∘<𝜃23<53∘ 𝜃13<11∘ 33∘<𝜃12<37∘ Relevant for

0n2b decayAtmospheric/LBL-Beams Reactor Solar/KamLAND

me t

me t

m t

1Sun

Normal

2

3

Atmosphere

me t

me t

m t

1Sun

Inverted2

3

Atmosphere

72–80 meV2

2180–2640 meV2

Tasks and Open Questions• Precision for q12 and q23

• How large is q13 ?• CP-violating phase d ?• Mass ordering ? (normal vs inverted)• Absolute masses ? (hierarchical vs degenerate)• Dirac or Majorana ?


Antineutrino Oscillations Different from Neutrinos?

Dirac phase causes different 3-flavor oscillationsfor neutrinos and antineutrinos

Distance [1000 km] for E = 1 GeV

same as

𝜈𝑒→𝜈𝜇

𝜈𝑒→𝜈𝜇

𝝂𝐞=𝑐12𝑐13𝝂𝟏+𝑠12𝑐13𝝂𝟐+𝑠13𝑒−𝑖 𝛿𝝂𝟑

𝝂𝐞=𝑐12𝑐13𝝂𝟏+𝑠12𝑐13𝝂𝟐+𝑠13𝑒+𝑖 𝛿𝝂𝟑


Neutrino CarabinerNamed for a subatomic particlewith almost zero mass, …

nGreek “nu”Now also in color


“Weighing” Neutrinos with KATRIN• Sensitive to common mass scale m for all flavors because of small mass differences from oscillations• Best limit from Mainz und Troitsk m < 2.2 eV (95% CL)• KATRIN can reach 0.2 eV• Under construction• Data taking foreseen to begin in 2012

http://www-ik.fzk.de/katrin/


“KATRIN Coming” (25 Nov 2006)


Pie Chart of Dark Universe

Dark Energy 73% (Cosmological Constant)

Neutrinos 0.1-2%

Dark Matter23%

Ordinary Matter 4%(of this only about 10% luminous)


Cosmological Limit on Neutrino Masses

JETP Lett. 4 (1966) 120

Cosmic neutrino “sea” 112 cm-3 neutrinos + anti-neutrinos per flavor

Ω𝜈h2=∑ 𝑚𝜈

93 eV<0.23

For allstable flavors∑𝑚𝜈≲20eV


Weakly Interacting Particles as Dark Matter

Almost 40 years ago, beginnings of the idea of weakly interacting particles (neutrinos) as dark matter

Massive neutrinos are no longer a good candidate (hot dark matter)

However, the idea of weakly interacting massive particles (WIMPs) as dark matter is now standard


What is wrong with neutrino dark matter?Galactic Phase Space (“Tremaine-Gunn-Limit”)

Maximum mass density of a degenerateFermi gas

𝜌max=𝑚𝜈𝑝max3

3𝜋 2⏟𝑛max

=𝑚𝜈 (𝑚𝜈𝑣escape )

3

3𝜋 2

Spiral galaxies mn > 20–40 eVDwarf galaxies mn > 100–200 eV

Neutrino Free Streaming (Collisionless Phase Mixing)

NeutrinosNeutrinos

Over-density

• At T < 1 MeV neutrino scattering in early universe is ineffective• Stream freely until non-relativistic• Wash out density contrasts on small scales

• Neutrinos are “Hot Dark Matter”• Ruled out by structure formation


Structure Formation with Hot Dark Matter

Neutrinos with Smn = 6.9 eVStandard LCDM Model

Structure fromation simulated with Gadget codeCube size 256 Mpc at zero redshift

Troels Haugbølle, http://users-phys.au.dk/haugboel


Power Spectrum of Cosmic Density Fluctuations

Tegm

ark,

TAU

P 2

003


Power Spectrum of CMB Temperature Fluctuations

Acoustic Peaks

Sky map of CMBR temperature fluctuations

Multipole expansion

Angular power spectrum

Δ (𝜃 ,𝜑 )=𝑇 (𝜃 ,𝜑 )− ⟨𝑇 ⟩⟨ 𝑇 ⟩

Δ (𝜃 ,𝜑 )=∑ℓ=0

∞

∑𝑚=−ℓ

ℓ

𝑎ℓ𝑚𝑌 ℓ𝑚 (𝜃 ,𝜑 )

𝐶ℓ= ⟨𝑎ℓ𝑚∗ 𝑎ℓ𝑚⟩= 12 ℓ+1 ∑𝑚=−ℓ

ℓ

𝑎ℓ𝑚∗ 𝑎ℓ𝑚


Latest Angular Power Spectrum (WMAP 7 years)

Komatsu et al. (WMAP Collaboration), arXiv:1001.4538

Ratio 1st/3rd

peak fixes zeq


Radiation Content at CMB Decoupling

• Existence of cosmic neutrino sea clearly confirmed by precision cosmology• All analyses find mild indication for excess radiation

• Planck data will fix Neff to ±0.26 (68% CL) or better

Komatsu et al. (WMAP Collaboration), arXiv:1001.4538

WMAP alone

+ Large-scale structure(LSS) and H0


Weak Lensing - A Powerful Probe for the Future

Unlensed Lensed

Distortion of background images by foreground matter


Mass-Energy-Inventory of the Universe

10-3 10-2 10-1 1 WAssuming h = 0.72

Luminous TotalBaryons

LDark Matter

1 10 eV

Tritium (Mainz/Troitsk)NeutrinosSuper-K

Future Tritium (KATRIN)

Weak lensing tomography

CMB & LSS

∑ 𝑚𝜈

310-2 10-1


Are Neutrinos their own Antiparticles?

Matter

Quarks

-1/3 +2/3

d u

s c

tb

e

𝜈𝜏𝜏

Leptons

-1 0

1st Family

2nd Family

3rd Family

Charge

Weak Interaction

Strong Int’n

Electromagnetic Int’n

Gravitation

Anti-Leptons Anti-Quarks

𝜈𝜏

0

𝜏+¿ ¿

+1 -2/3

uct

+1/3

b

Anti-Matter

Strong Int’n

Electromagnetic Int’n

Much less anti-matter in the universe: Baryon asymmetry of the Universe (BAU)

0 0

„Majorana Neutrinos” are their own antiparticles

𝜈 e𝜈𝜇

𝜈𝜏


Solar Neutrinos vs. Reactor Antineutrinos

Fissionable nucleus

Neutron

Nucleussplitting

Fission products w/ neutron excess

unstable nuclei effectively decay by

Detection by inverse decay

Reines and Cowan 1954–1956

Energy26.7 MeV

Ray Davis radiochemical detector (1967–1992)

Amounts to neutino capture by neutron

Does not work for reactor flux!


Role of Neutrino Helicity (Handedness)Basic production processin reactors

Basic production processin the Sun

Cowan & Reines detectorin fast-moving rocket,overtakes small-mass solar

Majorana neutrinos:Helicity flip anti-neutrino property dependson Lorentz frame

Anti-neutrinos alwaysright-handed helicity

Neutrinos alwaysleft-handed helicity


Neutrinoless bb Decay

Some nuclei decay only bythe bb mode, e.g. Ge-76

76Ge76Se

76As

0+

2-

2+

0+

Half life 1021 yrStandard 2n mode 0n mode, enabled

by Majorana mass

|𝑚𝑒𝑒|=|∑𝑖=1𝑁

𝜆𝑖|𝑈 𝑒𝑖|2𝑚 𝑖|Measured

quantity

Best limitfrom 76Ge

|𝑚𝑒𝑒|<0.35eV


GERDA Germanium Double Beta Experiment Bare enriched Ge-76 array in liquid Ar,located in Gran Sasso

Phase I (being commissioned)18 kg (HdM/IGEX) + 15 kg natural Ge Test claim of Klapdor-Kleingrothaus

Phase II, O(100 kg years)Add 20 kg enriched new detectors Degenerate masses: 75–130 meV

Phase III, O(1000 kg years)with Majorana collaboration?1-ton scale Inverted hierarchy: 24–41 meV

Several other large projects worldwide


𝑚𝐷𝑚𝐷2 /𝑀 𝑀

See-Saw Model for Neutrino Masses

1027eV

Planckmass

GUTscale

Electroweak scale

QCDscale

Cosmologicalconstant

10241021101810151012109106103110− 3

(𝜈𝐿 ,𝑁𝑅 )( 0 𝑚𝐷

𝑚𝐷 𝑀 )( 𝜈𝐿

𝑁𝑅)

(𝜈𝐿 ,𝑁𝑅 )(𝑚𝐷2 /𝑀 00 𝑀 )( 𝜈𝐿

𝑁𝑅)

Mass matrix for one family of ordinary and heavy r.h. neutrinos

Diagonalization

One light and one heavy Majorana neutrino


Leptogenesis by Majorana Neutrino Decays

Heavy sterileneutrino N

Lepton

Higgs

NN

ℓ

Φ

Φ

+

CP-violating decays ofheavy sterile neutrinos byinterference of tree-levelwith one-loop diagram


Baryogenesis by Leptogenesis?

Dark Energy 73% (Cosmological Constant)

Neutrinos 0.1-2%

Dark Matter23%

Ordinary Matter 4%(of this only about 10% luminous)


Applied Neutrino Physics


Reactor Monitoring


Neutrino Monitoring of Nuclear Reactors

Rea

ctor

Pow

er (%

)

-20

0

20

40

60

80

100

Date06/2005 10/2005 02/2006 06/2006 10/2006

Det

ecte

d A

ntin

eutr

inos

per

day

0

100

200

300

400

500

Predicted rate Reported powerObserved rate, 30 day average

Cycle 14Cycle 13outage

Cycle 13

San Onofre Nuclear Reactor(California)

Neutrino measurements withSONGS1 detector (1m3 Scintillator)

• 3.4 GW thermal power• Produces • 3800 neutrino reactions/day

in 1 m3 liquid scintillator

• Relatively small detectors can measure nuclear activity without intrusion• Of interest for monitoring by International Atomic Energy Agency (IAEA)


Geo Neutrinos: What is it all about?

We know surprisingly little aboutthe Earth’s interior• Deepest drill hole 12 km• Samples of crust for chemical analysis available (e.g. vulcanoes)• Reconstructed density profile from seismic measurements• Heat flux from measured temperature gradient 30-44 TW (Expectation from canonical BSE model 19 TW from crust and mantle, nothing from core)

• Neutrinos escape unscathed• Carry information about chemical composition, radioactive energy production or even a hypothetical reactor in the Earth’s core


Geo NeutrinosExpected Geoneutrino Flux

Reactor Background

KamLAND Scintillator-Detector (1000 t)


Latest KamLAND Measurements of Geo NeutrinosK. Inoue at Neutrino 2010


AAP 2011 Vienna

http://aap2011.in2p3.fr/


Sanduleak -69 202Sanduleak -69 202

Large Magellanic Cloud Distance 50 kpc (160.000 light years)

Tarantula Nebula

Supernova 1987A23 February 1987


Neutrino Signal of Supernova 1987AKamiokande-II (Japan)Water Cherenkov detector2140 tonsClock uncertainty 1 min

Irvine-Michigan-Brookhaven (US)Water Cherenkov detector6800 tonsClock uncertainty 50 ms

Baksan Scintillator Telescope(Soviet Union), 200 tonsRandom event cluster 0.7/dayClock uncertainty +2/-54 s

Within clock uncertainties,all signals are contemporaneous


2002 Physics Nobel Prize for Neutrino Astronomy

Ray Davis Jr.(1914–2006)

Masatoshi Koshiba(*1926)

“for pioneering contributions to astrophysics, inparticular for the detection of cosmic neutrinos”

Crab Nebula

Physics Opportunities withSupernova Neutrinos

Georg Raffelt, Max-Planck-Institut für Physik, München

2nd Schrödinger LectureTuesday, 10 May 2011, 16 ct


Cosmic Rays

Air Shower: 1019 eV primary particle 100 billion secondary particles at sea level Victor Hess (1911/12)

100 years later we are still asking

What are the sourcesfor the primarycosmic rays?


Neutrino Beams: Heaven and Earth

Target:Protons or Photons

Approx. equal fluxes ofphotons & neutrinos

Equal neutrino fluxesin all flavors due tooscillationsF. Halzen (2002)

𝜋 0

𝜸

𝜋±

𝝁𝝂𝝁

𝒆𝝂𝒆𝝂𝝁

𝝂𝒆𝝂𝝁𝝂𝝉

p


Nucleus of the Active Galaxy NGC 4261


Scott Amundsen Base at the South Pole


IceCube Neutrino Telescope at the South PoleInstrumentation of 1 km3 antarcticice with 5000 photo multiplierscompleted December 2010

Deep Core installed 2010Search for dark matter


IceCube Neutrino Sky

IceCube Collaboration, arXiv:1012.2137 and Gaisser at Neutel 2011

Full-sky map, based on 40 strings


ANTARES - Neutrino Telescope in the Mediterranean


Luminescent Ceatures of the Deep Sea

40K2 min

P.Coyle, Neutel 2011


Three Mediterranean Pilot Projects

NemoAntares

2500 m

3500 m 4500 m


Towards a km3 Detector in the Mediterranean

http://www.km3net.org


Frontiers of Neutrino Physics

Matter-Antimatter-Issues• Majorana masses (neutrinoless double beta decay)• Oscillation difference between and (Dirac phase)• Baryon asymmetry of the universe (leptogenesis)

Absolute Mass• Experimental determination• Role in cosmology for structure formation

Exploring the Universe with Neutrinos• Sources of high-energy cosmic rays• Next galactic supernova• Diffuse SN neutrino background in the universe• Sun• Earth• Reactor monitoring

Neutrinos at the center

n Astrophysics & Cosmology

Cosmic Rays

El

emen

tary

Par

ticle

Phy

sics

Neutrinos – Ghost Particles of the Universe

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