Fisica dei Neutrini

Misure dirette di massa0νββSolari

AtmosfericiReattori

AcceleratoriAstrofisica

Lucio.Ludovici roma1.infn.it - XV IFAE - Lecce 23 Aprile 2003

Lucio Ludovici / INFN-Roma

500+ Cited exp. papers 1990-20021. EVIDENCE FOR OSCILLATION OF ATMOSPHERIC NEUTRINOS

Super-Kamiokande Collaboration (Y. Fukuda et al.). Phys.Rev.Lett.81:1562 (1998) hep-ex/9807003 15972. OBSERVATION OF TOP QUARK PRODUCTION IN ANTI-P P COLLISIONS

CDF Collaboration (F. Abe et al.). Phys.Rev.Lett.74:2626 (1995) hep-ex/9503002 9193. OBSERVATION OF THE TOP QUARK.

D0 Collaboration (S. Abachi et al.). Phys.Rev.Lett.74:2632 (1995) hep-ex/9503003 8784. ATMOSPHERIC νµ /νe RATIO IN THE MULTIGEV ENERGY RANGE

Kamiokande Collaboration (Y. Fukuda et al.). Phys.Lett.B335:237 (1994) 7295. INITIAL RESULTS FROM THE CHOOZ LONG BASELINE REACTOR NEUTRINO OSCILLATION EXPERIMENT.

CHOOZ Collaboration (M. Apollonio et al.). Phys.Lett.B420:397 (1998) hep-ex/9711002 6596. OBSERVATION OF A SMALL ATMOSPHERIC νµ /νe RATIO IN KAMIOKANDE.

Kamiokande-II Collaboration (K.S. Hirata et al.). Phys.Lett.B280:146 (1992) 6137. FIRST MEASUREMENT OF THE RATE FOR THE INCLUSIVE RADIATIVE PENGUIN DECAY b → s γ.

CLEO Collaboration (M.S. Alam et al.). Phys.Rev.Lett.74:2885 (1995) 6118. LIMITS ON NEUTRINO OSCILLATIONS FROM THE CHOOZ EXPERIMENT.

CHOOZ Collaboration (M. Apollonio et al.). Phys.Lett.B466:415 (1999) hep-ex/9907037 5789. EVIDENCE FOR νµ → νe OSCILLATIONS FROM THE LSND EXPERIMENT AT LAMPF.

LSND Collaboration (C. Athanassopoulos et al.). Phys.Rev.Lett.77:3082 (1996) nucl-ex/9605003 55310. EVIDENCE FOR TOP QUARK PRODUCTION IN p p COLLISIONS AT S 1/2 = 1.8-TeV.

CDF Collaboration (F. Abe et al.). Phys.Rev.D50:2966 (1994) 54411. MEASUREMENT OF A SMALL ATMOSPHERIC MUON-NEUTRINO / ELECTRON-NEUTRINO RATIO.

Super-Kamiokande Collaboration (Y. Fukuda et al.).Phys.Lett.B433:9 (1998) hep-ex/9803006 53412. MEASUREMENT OF THE RATE OF νe + d → p + p + e- INTERACTIONS PRODUCED BY B8 SOLAR

NEUTRINOS AT THE SUDBURY NEUTRINO OBSERVATORY.SNO Collaboration (Q.R. Ahmad et al.). Phys.Rev.Lett.87:071301 (2001) nucl-ex/0106015 525

13. STUDY OF THE ATMOSPHERIC NEUTRINO FLUX IN THE MULTI-GEV ENERGY RANGE. Super-Kamiokande Collaboration (Y. Fukuda et al.). Phys.Lett.B436:33 (1998) hep-ex/9805006 525

14. MEASUREMENT OF THE SOLAR ELECTRON NEUTRINO FLUX WITH THE HOMESTAKE CHLORINE DETECTOR.Bruce T. Cleveland et al. Astrophys.J.496:505 (1998) 524

15. THE νe AND νµ CONTENT OF THE ATMOSPHERIC FLUX.R. Becker-Szendy et al (IMB Coll.) Phys.Rev.D46:3720 (1992) 521

1930: Dear Radioactive...

Energia

Emax

N’

N Emax

Problem: continuous spectrum in β decay.

Pauli's neutronen: a new, unseen particle.spin ½ , neutral, almost massless, weakly interacting.

“I have to replace something we do not understand with something else we cannot observe.”

“[...] there is no practically possible way of observing the neutrino” H.Bethe, R.Peierls, Nature (1934)

Age 73. Still in a good shape1930 ν existence postulated Pauli1934 ν interaction theory and name Fermi1938 Solar ν flux calculation Bethe1946 Idea of ν chlorine detector Pontecorvo1956 ν interactions observed Reines & Cowan1957 Idea of ν oscillation Pontecorvo1958 Left-handed ν Goldhaber1962 2 ν's, νµ≠νe Lederman, Schwartz & Steinberger1968 Solar neutrino deficit Davis1973 ν NC interactions observed Gargamelle1975 τ and the third ν Perl1986 Solar deficit again Kamiokande1987 ν from SN1987A Kamiokande, IMB1989 3 light neutrino families LEP Collaborations1991 Still solar deficit Gallex, SAGE1998 Atmospheric ν oscillation Super-Kamiokande2002 Solar ν oscillation confirmed SNO, KamLand

τ MULTIPIONSDECAY

π DECAYAT REST

Mass Direct Measurements Direct kinematic limits on mνx

2= Σ |Uxi |2mi2

mνe < 2.2 eV (1) Mainz experiment, eventually mν2>0.

Troitsk: 2.5 eV (+ seasonal anomaly !?)→ ∼0.3 eV (KATRIN). Criogenic microcalorimetry: 10 eV soon, R&D to sub eV sensitivity.

mνµ <190 keV(1) Endpoint of the muon spectrum in pion decays. Limited by the π mass uncertainty (∆m/m=2.6.10-6).→ ∼10 keV using decay in flight at the BNL (g-2) ring.

mντ <15.5 MeV(1) Aleph,Cleo,Opal: exploit kinematic correlation Mh,Eh of the multipion system in τ→nπ(πo)ντ. → Babar, Belle → 3 eV (systematics ?!).

( 1) 95% CL

TRITIUMDECAY

Direct Mass Limits

Year

ν e/ν

µ/ν τ

mas

s (e

V/K

eV/M

eV)

νe (eV)

νµ (KeV)

ντ (MeV)

Note different units!

Nice trend.

Small oscillation ∆m's ⇒ upper limit to v masses given by the ve direct limit

How far will it go? Promise for sub-eV (e.g. Katrin) in Tritium.

Double Beta DecayDouble Beta DecaySM 0νββ observed with radiochemical inclusive methods.Direct counting experiment searches for the non-SM 0νββ (∆L=2) Physics beyond SM or limit on T1/2

→ limit on <mν>=Σ Uei2mi

0νββ

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ν

0 1+2 3 4

5 67 89 :; <

=>? @AB B CED

F FG H IJKL MEN

OPQ RES

TU VXW YZ W [ \] ^_` aEbcd ef g

Sensitive to majorana masses.

Cancellations possibles.

<mν> limited (∼0.5 eV) by the uncertainty on the nuclear matrix element calculations.

In models with neutrino mass degeneration → constraint on the mixing angles Σ Uei

2

Evidence for 0νββ ?

Evidence for neutrinoless double beta decayH.V. Klapdor-Kleingrothaus et al., Mod. Phys. Lett., A16 (2001) 2409

Comment on “Evidence for neutrinoless double beta decay”C.E. Aalseth et al., Mod. Phys. Lett., A17 (2002) 1475

....

T1/2 = (0.8-18.3) 1025 y, 95%CL0νββ

T1/2 = 1.5 1025 y , best fit0νββ

<mν> = (0.11-0.56) eV, 95%CL

<mν> = 0.39 eV, best fit

CLAIM

CRITICISM

.......

97%, 2.2σ Bayesian method99.8%, 3.1σ PDG method

Neutrinos from the Sun

Burning protons in to 4He, the Sunradiates energy and electron neutrinos.

The Standard Solar Model predictsthe neutrino flux and spectrum.

Solar NeutrinosFl

ux

(cm

-2 s-1

/MeV

)

Chl or i neHome s t a keνe + 37Cl →37Ar + e-

Ga l l i umSAGE, Ga l l e x , GNOνe + 71Ga →71Ge + e-

Wa t e rKa mi oka nde , Supe r Kνx + e- → νx + e- (ES)

D2OSNOνx + e- → νx + e- (ES)νe + d → p + p + e- (CC)νx + d → n + p + νx (NC)

Eν (MeV)

±10%

±1.5%

±20%-16%

pep

8B

hep

±1%

±10% 7Be7Be

??

pp

Water, D2OChlorine

Gallium

Bahcall-Pinsonneault 2000

Solar Problem and SNO

8B 7Be pp, pep CNO experiments

7.7+1.3-1.1

Cl H2OGa

129+9-7

2.58±0.23Homestake

SAGE

Gallex +

GNO

75+8-7 74+7

- 6

1.0+0.20- 0.16

0.47±0.02SuperK

(ES)

0.54±0.08

Kamiokande(ES)

0.35±0.03SNO (CC)

D2O

1.0+0.20- 0.16

SNO (NC)

1.01±0.12

ν as seen in SNO νx + e- → νx + e-

νe + d → p + p + e-

νx + d → n + p + νx

ES

CC

NC

In SNO (D2O) as in SK (H2O)Mainly νe but also νµ,ντ (1:6)Strong Θν sensitivity.

Good energy measurementνe onlyWeak directionality: ∝1-1/3cos(Θν)

Equally sensitive to all νMeasure the total 8B flux

SNO Analysis

CC 1967.7 +61.9 +60.9

+26.4 +25.6ES 263.6 +49.5 +48.9NC 576.5#E

VE

NTS

Reactor νe Disappearance162 ton yearEprompt > 2.6 MeVObserved 54 eventsExpected 86.8 ± 5.6 eventsBackground 0.95 ± 0.99 events

NOBS-NBCKG NEXP

= 0.611 ± 0.085 ± 0.041

99.95% CL main bckg: 9Li/8He (β,n)

∆m2 = 5.5x10-5 eV2

sin2 2Θ = 0.833

Energy Spectrum

Fit resultsRate only excluded Shape only allowed Rate&Shape allowed

Pin down the LMA among the solutions allowed by previous experiments.Two subregions survive: LMA-I and LMA-II.

Atmospheric ν'sπ+

e+ µ+

≈ 15 Km

νµνµνe

cosmic ray

π+ →µ+ νµ →e+ νµνe

π− →µ− νµ →e− νµνe

R(E) = 2 (νe+νe)

(νµ+νµ)E <≈ 1GeV

15 Km

HORIZON500 Km

13,000 Km

Eve

nts

cosΘ cosΘ

DOWNUPDOWNUP

DOWNWARD

UPWARD

Super-Kamiokande-II

Super-Kamiokande cleaned after Nov.2001 accident

Zenith Distributions

Best fit result:χ2

min = 132.4/137 doffor νµ→ντ withsin22θ=1, ∆m2 = 2.4 . 10-3 eV2c os Θ

even

ts

Calculations: ∆Φatm/Φatm= 20%

up down

Up/Down = 0.54±0.04±0.01

Evidence for oscillation:50% deficit of νµ fluxνe flux as expectedΦup∼ ½� Φdown !

SuperK statistic 79.5 kt.yr

Up-ward muons

<Eν> ∼ 100 GeV <Eν>∼<E> PC events

K2K

Neutrino Beam line at KEK

Near detector at 300m

Super-Kamiokande at 250 Km

SciBar

Atmospheric ν at LBL

56 FC events observed (30 1-ring + 26 multi-ring)

80.1 FC events expected+6.2-5.4

∆m2=2.8 10-3eV2, 90% CL per full mixing+1.1-1.3

Prob{null.osc.} < 1.3%

Absolute flux

deficit

Mixing parameters

1-ring events

Best FitNo oscill. (Φ free)No oscill. (Φ expected)

Spectral distortion

Prob{null.osc.} ~ 16%

Reproduce “in Lab” and confirm

atmospheric ν

Discover an oscillation

pattern

Measure oscillation parameters

LSND ?

Excess 87.9 ± 22.4 ± 6.0 eventsP(νµ→νe)= (0.264 ± 0.067 ± 0.045) %

∆m2 ≈ 1 eV2

3.3σ evidence

167t mineral oilCherenk.+Scintill.

Prompt Cherenkov coincidence with delayed scintillation:νe p→e+n →n p→d γ( 2 . 2Me V)

More (sterile) ν's ?Discarding LSND, νµ,νe,ντ are enough to fit all experimental data till now.If LSND is confirmed → three ∆m's paradox: ≈10-4,≈10-3,≈100 eV2

Either Atmospheric, Solar or LSND is not due to oscillation.

A 4th (at least) sterile neutrino exists.

The holy CPT symmetry is violated. mν ≠ mν, P(νA→νB)≠ P(νA→νB)

mν mν

2+2 3+1

Wait for unambiguous confirmation or refutation. MiniBooNE at Fermilab expects 5σ sensitivity.

Results in 2005.

Experimental facts on neutrino mass and mixing

νe → νµ,ντ with ∆m2 10� -4 eV2, almost (not fully) maximal mixing.

νµ and/or ντ NC appearance from the Sun in SNO.“Lab Test”: reactor νe disappearance at L≈200Km in Kamland (4.6σ)

νµ →ντ with ∆m2 = (1.6÷3.9).10-3 eV2, sin22θ > 0.92 at 90%CL

Super-K upward-going atmospheric νµ disappearanceMost likely νµ →ντ from πo and matter effects in Super-K (2÷3σ)“Lab Test”: νµ disappearance in accelerator from K2K-I (2÷3σ)

νµ → νe with ∆m2~ 0.1-1 eV2

LSND claimed evidence of neutrino oscillation.Unseen by KARMEN with marginal sensitivityControversy to be solved by Mini-BooNE (results in 2004-5)

1 0 0 0 C23 S 23

0 -S 23 C23

C13 0 S13e i δ

0 1 0-S 13e -i δ 0 C13

C12 S 12 0-S 12

C12 0 0 0 1

U = UA.U13.US =

hji k l mon pi q r →

s tu v v wx y y{z | z }~ z v�� � u }� � z v u } w� � �E� � u v z ∆m212 ∆m223 θ12 θ23 θ13 δ

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The Mixing Matrix

ν �

νµντ

= Uαi

ν �

ν �

ν �

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∆jk = ∆m2jk(eV2)L(Km)/Eν (GeV) , Wαβ = Uαj Uβj Uαk Uβk∗ ∗

P(να → νβ) = δαβ - 4 Σ Re[Wαβ] sin2 ∆jk( ±) 2 Σ Im[Wαβ] sin 2∆jk jk

k>j k>j

jk

CP odd

j k

(-) (-)

Approximate probabilities for terrestrial baselines, with ∆12<<1:

P(νe → νµ) ≅ sin22θ13 sin2θ23 sin2 ∆23 = sin22θµe sin2 ∆23

P(νµ → ντ) ≅ cos4θ13 sin22θ23 sin2 ∆23 = sin22θµτ�sin2 ∆23

P(νe → ντ) ≅ sin22θ13 cos2θ23 sin2 ∆23 =

P(νµ → νµ) ≅ �������������������=�1 – (sin22θµτ + sin22θµe ) sin2 ∆23

P(νe → νe) ≅ 1 − s i n 22θ13 s i n 2 ∆23

Only 3 parameters are relevant: θ23 ∆m23 θ13 Oscillation 3 flavour probabilities reduce to 2 flavour probabilities with effective mixing angles:

sin22θµτ = cos4θ13 sin22θ23 ≅ sin22θ23

sin22θµe = sin22θ13 sin2θ23 ≅ 0.5 sin22θ13

Effective Mixing Angles

Knowledge of mixing parameters

´jµ ¶{· ¸ ν

¹{º » ¼¾½À¿ NC appearance in SNO“Lab” confirmation: claim of disappearance in KamLand

Á ÃÄ ÅÆ Ç{È É Ê²Ë ν

ÌÍÏÎ Ð Ñ ÑÒ Ð ÓÕÔ Up/Down asymmetry in Super-K “Lab” confirmation: indication of disappearance in K2K

νe → νµ Negative result in CHOOZ

δ No experimental input

∆m223 = ∆m2

atm=1.6÷4�10-3 eV2

∆m212 = ∆m2

sun=(0.6÷0.9) 10-4 or (1.3÷2.0)�10-4 eV2

θ23 ∼ 45o

θ12 ∼ 45o

θ13 < 13o

δ = [0,2π]

<

eV

Ö × Ø Ù ÚÛÜÝ Þ Ù ß

à á â Ö ã

eV

m0

Hierarchical Degenerate

Σmν ≅ ∆matm Σmν ≅ 2 ∆matm Σmν ≅ 3 mo

Neutrino Mass Scale

äå h2 < 0.0076 æ

mν� < 0.71 eV mo < 0.23 eVWMAP

COBEClosing the gap on oscillation ∆m's

Dawn of ν Astronomy

Hubble Telescope

12 ν events in Kamiokande 8 ν events in IMB

SN1987A

Super-Kamiokandeimage of the Sunwith neutrinos

ν Astronomy Goals

GALACTIC

EXTRAGALACTIC

?

TeVGeV PeV EeV

AGN, GRB, Micro-Quasars,... Very high energy: GRB, E>1047 J (≈ 1 solar mass) in a few second

BeppoSax

Neutrino AstrophysicsGamma Ray Bursts emitted neutrino:

E2dN/dE < 4.10-4 . min(1,E/Ebreak) TeV cm-2 (Amanda)Pointlike continuous sources:

Different limits for spectral indexes E-2-E-3

High energy diffused fluxE2dN/dE < 8.4 10-7 GeV s-1 sr-1 cm-2 (Amanda)

Amanda upward muons

Experimental sensitivities approaching model's expectations

Upcoming:ANTARES in the Mediterranean Sea

Future: Km3 class detectors (intense R&D):ICECUBE, NEMO,.... 1/� emisphere.

Conclusions & Outlook

We got two mass differences at 30% precision

We have two angles: one almost maximal, one large

We have an upper limit on the third angle

We have no hints on the CP phase

We are slowly setting an absolute mass scale

We do not know if neutrinos are Majorana or Dirac

Why this is as it is ?

Surprises ?

MINOS, CNGS

JHFν,...

HyperK, νFact

CMB, Katrin,...

0νββ...

GUT, X-DIM,..?

Neutrino Nobels

1988: Lederman, Schwartz and Steinberger1995: Perl and Reines2002: Davis and Koshiba

? :