Upload
dangliem
View
237
Download
0
Embed Size (px)
Citation preview
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
��� �� � � � � � � � � � �
� � �� � � � � � � � �� �
� � �� �� � �
� � � � � �
�� � �� �� � !
" � � # � $ � �� �% � & � &
� � � � � ' � � (� �
� � )+* � � � ,& � �
� � � !� (
- �. � � ) � � �
/ �
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
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
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
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
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
� �o� � �� ��� � ��� � � � � �� �
The Mixing Matrix
ν �
νµντ
= Uαi
ν �
ν �
ν �
��� � ¡£¢ ¤¥ ��
� ¦¨§ � © ª «¢ « �
¬¢ ® « ¥ ¡¢ ¤ ¥ � �
� ¦¯§ � © ª «¢ « � ª�¢ °²± ¢ ª ª � ¦¨§ � © ª «¢ « �
«¢ ® � ª ¢ ³ ¦ �� � © « � °¢ ª �
∆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,..?