neutrino oscillations: experimental triumphs, remaining ... · neutrino oscillations: experimental...
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Neutrino Oscillations:Neutrino Oscillations:experimental triumphs,experimental triumphs,remaining puzzlesremaining puzzles
Giorgio GrattaPhysics Department, Stanford
SSI 2004 Experimental Neutrino Oscillations - Gratta 2
What we do know: What we do know: -- Status of neutrino mixingStatus of neutrino mixing
How did we learn it: How did we learn it: -- Solar neutrinoSolar neutrino-- Atmospheric neutrinoAtmospheric neutrino-- Reactor neutrinosReactor neutrinos-- K2KK2K
Addressing remaining puzzles in neutrino mixing:Addressing remaining puzzles in neutrino mixing:-- LNSD/LNSD/miniBooneminiBoone see Sam Zellersee Sam Zeller-- θθ13 13 experimentsexperiments-- Hierarchy/CP violation: Hierarchy/CP violation: νν--fact/fact/ββ--beamsbeams-- Absolute m, Absolute m, Majorana/DiracMajorana/Dirac νν
see Steve Elliottsee Steve Elliott
Impossible to be complete: I will just make an arbitraryImpossible to be complete: I will just make an arbitrary--and hopefully interestingand hopefully interesting-- selectionselection
SSI 2004 Experimental Neutrino Oscillations - Gratta 3
If mIf mνν≠≠0 then the 0 then the 3 weak3 weak--interactions interactions eigenstateseigenstatescan be represented as superposition of mass can be represented as superposition of mass eigenstateseigenstates
jν
∑=j
ljlj U νν
jljj l
LEmiljl
LEmi
lljj UeUeU ll
′′′
−− ∑∑∑ ≅≅ ννν *)2/()2/( 22
Neutrinos are produced and detected by weak interactionNeutrinos are produced and detected by weak interactionbut propagate in vacuum as mass but propagate in vacuum as mass eigenstateseigenstates……
From LEP and SLC we know that there are2.981±0.008 active, light ν flavors
We also know that 3 ν flavors were active inBig Bang Nucleosynthesis
Neutrino oscillations
SSI 2004 Experimental Neutrino Oscillations - Gratta 4
⎟⎟⎟
⎠
⎞
⎜⎜⎜
⎝
⎛•
⎟⎟⎟
⎠
⎞
⎜⎜⎜
⎝
⎛•
⎟⎟⎟
⎠
⎞
⎜⎜⎜
⎝
⎛
•⎟⎟⎟
⎠
⎞
⎜⎜⎜
⎝
⎛
=⎟⎟⎟
⎠
⎞
⎜⎜⎜
⎝
⎛=
+ βα
α
δ
δ
τττ
µµµ
θθθθ
θθ
θθθθθθ
i/2i-
i-
i-
i-
ee
e
e
CP
CP
0000001
00
001
0010
0
10000
2/
2323
2323
1313
1313
1212
1212
321
321
e3e2e1
cossin-sincos
cossin-
sincoscossin-sincos
UUUUUUUUU
U
Solar νKamLAND
Atmospheric νK2K
Neutrinolessdouble beta
decay
Chooz/Palo Verde
information onCP is here
A possible representation of thePontecorvo-Maki-Nakagawa-Sakata matrix
θ12~32° θ13<7° @ 90%CL θ23~45°
Off axisFuture reactorsFuture solar
ν exp.Minos et al
Neutrinofactory ?
SSI 2004 Experimental Neutrino Oscillations - Gratta 5
Sign of ∆m213 (Future accelerator experiments)
2.8 eV
From tritium
endpoint(M
aintzand Troitsk)
0.3 eV
From 0νββ
if νis M
ajorana
?
Oscillations give the proof that neutrino massesare non-zero, but we still do not know the absolute
mass scale and the hierarchy
~1 eV
From W
MA
P
Time of flight from
SN1987A
(PDG 2002)
~20 eV
~8.3·10-5 eV2
~8.3·10-5 eV2
solar~2.7·10-3 eV2
solar~2.7·10-3 eV2
SSI 2004 Experimental Neutrino Oscillations - Gratta 6
MeVeHpp e 42.02 +++→+ + ν
ννee are abundant byare abundant by--products of products of nuclear fusion in the sunnuclear fusion in the sun
MeVHpep e 44.12 ++→++ − ν
MeVHepH 49.532 ++→+ γ
MeVpHeHe 86.12233 ++→+ α MeVBeHe 59.173 ++→+ γα eepHe να ++→+ +3
MeVLieBe e 8617.077 +++→+ − νγ MeVBpBe 14.087 ++→+ γ
MeVpLi 35.177 ++→+ αα MeVeBeB e 6.1488 +++→ + ν
MeVBe 38 ++→ αα
““pp” 99.75%pp” 99.75%
86%86% ““hephep” 2.4*10” 2.4*10--55
““77BeBe”” 99.89%99.89%
““pep” 0.25%pep” 0.25%
0.11%0.11%
14%14%
““88BB”” 0.11%0.11%
SSI 2004 Experimental Neutrino Oscillations - Gratta 7
L=10L=108 8 kmkm
But neutrinos are producedBut neutrinos are produceddeep inside the Sun, wheredeep inside the Sun, wheremost the fusion reactionsmost the fusion reactionstake placetake place
Matter effectsMatter effectsplayplay an essential rolean essential role
The detectors are located far away from the Sun
SSI 2004 Experimental Neutrino Oscillations - Gratta 8
Several experiments detecting solar neutrinosSeveral experiments detecting solar neutrinos
Chlorine: Chlorine: 3737Cl+Cl+ννee3737Ar+eAr+e--
HomestakeHomestake mine (US) Taking data from 1967mine (US) Taking data from 1967--2002 (!) 2002 (!) The “father” of all solar neutrino experimentsThe “father” of all solar neutrino experiments
Gallium: Gallium: 7171Ga+Ga+ννee7171Ge+eGe+e--
SAGE (SAGE (BaksanBaksan, Russia), , Russia), GallexGallex and GNO (and GNO (GranGran SassoSasso, Italy) , Italy) Lowest thresholdLowest thresholdCalibrated with a neutrino sourceCalibrated with a neutrino source
CerenkovCerenkov: : ee--++ννee ee--++ννee KamiokandeKamiokande and and SuperKamiokandeSuperKamiokande (Japan), SNO (Sudbury, Canada)(Japan), SNO (Sudbury, Canada) Largest statistics Largest statistics See See D.Casper’sD.Casper’s talktalk
CerenkovCerenkov: D: Dνν scatteringscattering SNO (Sudbury, Canada)SNO (Sudbury, Canada) For the first time measure For the first time measure ννee and and ννXX separatelyseparately See See D.WallerD.Waller’’ss talktalk
Radioc
hemical,
no r
eal-
time
info
rmat
ion
SSI 2004 Experimental Neutrino Oscillations - Gratta 9
Neutrino energy spectrum includes lines and continuaNeutrino energy spectrum includes lines and continua
SSI 2004 Experimental Neutrino Oscillations - Gratta 10
HomestakeHomestake Mine, Lead SDMine, Lead SD1400 m underground1400 m underground
615 tons of 615 tons of perchloroethileneperchloroethilene(C(C22ClCl44))
2.2*102.2*103030 atoms of atoms of 3737ClCl3636Ar or Ar or 3838Ar added to the Ar added to the
fluid as carrier gasfluid as carrier gas
SSI 2004 Experimental Neutrino Oscillations - Gratta 11
30 years of solar neutrinos with the Chlorine detector30 years of solar neutrinos with the Chlorine detectorExpectedExpectedfrom
SSMfrom
SSM
SSI 2004 Experimental Neutrino Oscillations - Gratta 12
1 SN
U =
1
1 SN
U =
1 νν
inte
ract
ion/
sec
per
10inte
ract
ion/
sec
per
103636
targ
et a
toms
targ
et a
toms
SSI 2004 Experimental Neutrino Oscillations - Gratta 13
7171 Ga ha
s lowe
r thre
shold:
Ga has
lower
thresh
old:
to dat
e, onl
y tech
nique
to dat
e, onl
y tech
nique
sensiti
ve to
pp neu
trinos
!
sensiti
ve to
pp neu
trinos
!
SAGE, Baksan
In In GallexGallex/GNO 30.3 ton of/GNO 30.3 ton ofGaGa in aqueous solution of in aqueous solution of GaClGaCl44. . 7171GeClGeCl44 is volatileis volatileand is purged/countedand is purged/counted
28 28 -- 50 ton of metallic50 ton of metallicGaGa kept liquid (>29.8 C)kept liquid (>29.8 C)
Extraction by Extraction by HClHCl etch andetch andGeCl4 and GeCl4 and ArAr purgepurge
SSI 2004 Experimental Neutrino Oscillations - Gratta 14
Both Both GaGa experiments haveexperiments havebeen calibrated with a been calibrated with a 5151CrCr
source of about 1 source of about 1 MCiMCi
51Cr source measurements
SAGE dataSAGE data
SNU
SNU
ExpectedExpectedfrom SSMfrom SSM
SSI 2004 Experimental Neutrino Oscillations - Gratta 15
In order to better understand the situation it would be In order to better understand the situation it would be nice to also measure thenice to also measure thetotaltotal number of neutrinosnumber of neutrinosfrom the Sun, from the Sun, all flavors togetherall flavors together
The SNO detector:The SNO detector:1 1 ktonkton of heavy waterof heavy water
SSI 2004 Experimental Neutrino Oscillations - Gratta 16
Charged Current (CC): Charged Current (CC): ννee+d+d⇒⇒p+p+ep+p+e--
Electron neutrinos onlyElectron neutrinos only
νxνx
e-e-
e-
dp
p
νe
d p
n
νxνx
Neutrino interactions in DNeutrino interactions in D22OO
Elastic Scattering (ES): Elastic Scattering (ES): ννxx+ e+ e-- ⇒⇒ ννxx +e+e--
0.1540.154••σσ((ννee)=)=σσ((ννµµ)=)=σσ((ννττ))this is all this is all SuperKSuperK seessees
Neutral Current (NC): Neutral Current (NC): ννxx+d+d⇒⇒p+n+p+n+ννxx
Same for all neutrino Same for all neutrino flavors !flavors !
SSI 2004 Experimental Neutrino Oscillations - Gratta 17
Energy Unconstrained
Remarkably the SNO measurement gives Remarkably the SNO measurement gives ΦΦNCNC>>ΦΦCCCC
So νe are missing, but the totalnumber of neutrinos is right !
Phys. Rev.Lett. 89 (2002) 011301
For upFor up--toto--date results date results see Waller’s talksee Waller’s talk
SSI 2004 Experimental Neutrino Oscillations - Gratta 18
5.53.69 ±
1 SN
U =
1
1 SN
U =
1 νν
inte
ract
ion/
sec
per
10inte
ract
ion/
sec
per
103636
targ
et a
toms
targ
et a
toms
3.59.66 ±
SSI 2004 Experimental Neutrino Oscillations - Gratta 19
Global fit to all solar neutrino Global fit to all solar neutrino expsexpseliminates most of the solutionseliminates most of the solutions
except for the MSWexcept for the MSW--LMA solutionLMA solution(The solar neutrino anomaly is(The solar neutrino anomaly is
a sort of neutrinoa sort of neutrino--birefringencebirefringenceof dense matter occurring because of dense matter occurring because
neutrinos have finite massesneutrinos have finite masses---- see Boris see Boris KayserKayser’’ talk)talk)
Clearly all this smells of flavor mixing…Clearly all this smells of flavor mixing…
SSI 2004 Experimental Neutrino Oscillations - Gratta 20
All of this is very interesting…All of this is very interesting…
…but wouldn’t it be great if we could …but wouldn’t it be great if we could reproduce it with artificial means ?reproduce it with artificial means ?
SSI 2004 Experimental Neutrino Oscillations - Gratta 21
ννee
ννee
ννee
ννee
ννee
ννee
ννee
ννeeννee
ννe e detectordetector
nucle
ar
nucle
ar
reac
tor
reac
tor
ννxx ??
LL
Look for a deficit of Look for a deficit of ννee and spectraland spectraldistortions at a distance Ldistortions at a distance L
Nuclear reactors are very intense sources of Nuclear reactors are very intense sources of ννee derivingderivingfrom betafrom beta--decay of the neutrondecay of the neutron--rich fission fragmentsrich fission fragments
NN
nn
nnnn
nnNN22
NN11
e-
eν
N’N’22
N’N’11
SSI 2004 Experimental Neutrino Oscillations - Gratta 22
Example: 235U fission
nXXnU 22123592 ++→+
94 140
Zr9440 Ce140
58
stable nuclei with Amost likely from fission
together these have98 protons and136 neutrons
so, on average 6 n have to decay to 6 p to reach stable matter
SSI 2004 Experimental Neutrino Oscillations - Gratta 23
fissionfissionMeV
e /6/200
ν
A typical large powerA typical large powerreactor producesreactor produces3 3 GWGWthermalthermal and and
66••10102020 antineutrinos/santineutrinos/s
Power/commercial reactors are generally usedsince only requirement is to have large power
the Chooz plant in France
SSI 2004 Experimental Neutrino Oscillations - Gratta 24
>99.9% of >99.9% of νν areareproduced by fissions inproduced by fissions in235235U, U, 238238U, U, 239239Pu, Pu, 241241PuPu
-
{contribution <10-3
not taken into account for neutrino
flux calculations
SSI 2004 Experimental Neutrino Oscillations - Gratta 25
nepe +→+ +ν)2.2( MeVdnp γ+→+
sµτ 200≈
10-40 keV
Eνmeasurement
Event tagging by coincidence in time, space and energy of the neutron capture
++ +−++≅epnne
mMMTTE )(ν
A specific signature is provided by the inverseA specific signature is provided by the inverse--ββ reactionreaction
1.8 MeV
{{
→→ only ~1.5 antineutrinos/fission can be detectedonly ~1.5 antineutrinos/fission can be detected
Threshold: Threshold: EEνν>1.8MeV>1.8MeV
SSI 2004 Experimental Neutrino Oscillations - Gratta 26
The The ννe e energy spectrumenergy spectrum
ν e+p→
n+e+
cros
sse
ction
(10-
43cm
2 )νν ee
+p→
n+e
+p→
n+e++
cros
scr
oss
sect
ion
(10
sect
ion
(10--
4343cmcm
22 ))
Eν (MeV)
Reactor Reactor ννee spectrum (spectrum (a.ua.u.).)Observed spectrum (Observed spectrum (a.ua.u.).)
SSI 2004 Experimental Neutrino Oscillations - Gratta 27
Statist
ical e
rrors
only
An experimentrelevant for
solar ν will have~100 km baselineand hence willneed a huge
detector and a “huge source”
SSI 2004 Experimental Neutrino Oscillations - Gratta 29
Many reactors contribute to the antineutrino flux at Many reactors contribute to the antineutrino flux at KamLANDKamLAND**EEνν>3.4MeV >3.4MeV ((EEpromptprompt>2.6MeV)>2.6MeV)
4.84.87.87.8··10103317.417.466986986YonggwangYonggwang6.16.19.99.9··10103311.511.544712712UlchinUlchinSouth Korea
South Korea
4.64.67.57.5··1010339.29.244735735KoriKori4.34.37.17.1··1010338.28.244709709WolsongWolsong
5.15.18.38.3··1010336.06.033561561IkataIkata6.36.31.01.0··1010443.83.822401401SimaneSimane9.39.31.51.5··1010446.56.533431431OnagawaOnagawa
2.12.13.43.4··1010335.35.322830830SendaiSendai4.84.87.87.8··10103310.110.144755755GenkaiGenkai
1.41.42.32.3··1010333.33.322783783TomariTomari
31.131.15.15.1··10104414.214.266349349Fukushima1Fukushima155.255.29.09.0··1010441.61.6118888SikaSika
29.529.54.84.8··10104413.213.244345345Fukushima2Fukushima2
62.562.51.01.0··1010554.54.522138138TsurugaTsuruga
Total NominalTotal Nominal
JapanJapan
74.374.31.21.2··10105510.210.244191191TakahamaTakahama114.3114.31.91.9··10105513.713.744179179OhiOhi
62.062.01.01.0··1010554.94.933146146MihamaMihama62.062.01.01.0··10105510.610.644214214HamaokaHamaoka
181.7181.7
3.33.3
24.324.3
PPthermtherm
(GW)(GW)
1.31.3··101066
1.61.6··101044
4.14.1··101055
FluxFlux(cm(cm--2 2 ss--11))
803.8803.87070--
10.110.111295295Tokai2Tokai2
254.0254.077160160KashiwazakiKashiwazaki
Rate Rate nooscnoosc**
(yr(yr--11 ktkt--11))Cores Cores (#)(#)
Dist Dist (km)(km)SiteSite
Deta
iled
powe
r an
d fu
elDe
taile
d po
wer
and
fuel
Compo
sition
calcu
lation
use
dCo
mpo
sition
calcu
lation
use
d
From electrical From electrical powerpower
Japanese averageJapanese averagefuel usedfuel used
SSI 2004 Experimental Neutrino Oscillations - Gratta 30
The total electric power produced “as a The total electric power produced “as a byby--product” of the product” of the ννs is:s is:
••~60 GW or...~60 GW or...••~4% of the world’s manmade power or…~4% of the world’s manmade power or…••~20% of the world’s nuclear power~20% of the world’s nuclear power
SSI 2004 Experimental Neutrino Oscillations - Gratta 31
A limited range of baselines contribute to the fluxA limited range of baselines contribute to the fluxof reactor antineutrinos at of reactor antineutrinos at KamiokaKamioka
Over the data periodOver the data periodReported hereReported here
Korean reactorsKorean reactors3.43.4±±0.3%0.3%
Rest of the worldRest of the world+JP research reactors+JP research reactors
1.11.1±±0.5%0.5%
Japanese spent fuelJapanese spent fuel0.040.04±±0.02%0.02%
SSI 2004 Experimental Neutrino Oscillations - Gratta 32
KamLANDKamLAND: : KamKamiokaioka LLiquid scintillatoriquid scintillatorAAntintiNNeutrinoeutrino DDetectoretector
••1 1 ktonkton liqliq. . ScintScint. Detector. Detector
in the in the KamiokandeKamiokande caverncavern
••1325 17” fast PMTs1325 17” fast PMTs
••554 20” large area PMTs554 20” large area PMTs
••34% photocathode coverage34% photocathode coverage
••HH22O O CerenkovCerenkov veto counterveto counter
SSI 2004 Experimental Neutrino Oscillations - Gratta 33
The completed detector, looking upThe completed detector, looking up
SSI 2004 Experimental Neutrino Oscillations - Gratta 34
Scintillator is a blend ofScintillator is a blend of20% pseudocumene and 20% pseudocumene and 80% 80% dodecanedodecane
Different density Different density paraffinesparaffines are usedare usedto tune the density of to tune the density of buffer to 4buffer to 4··1010--44 ofofthat of the scintillatorthat of the scintillator
PPO concentration is PPO concentration is 1.52 1.52 g/lg/l in scintillatorin scintillator
SSI 2004 Experimental Neutrino Oscillations - Gratta 35
Autoradiography of KamLANDAutoradiography of KamLAND
Top flange and Top flange and chimney regionchimney region
Central thermometerCentral thermometer
BalloonBalloon
Bottom flangeBottom flangeand plumbingand plumbing
In this region measure
238U = (3.5±0.5)x10 -18g/g
SSI 2004 Experimental Neutrino Oscillations - Gratta 36
A brief history of A brief history of KamLANDKamLAND
369.7369.7Oct Oct -- Jan 11Jan 1120042004Run BRun B
515.1515.1Mar 9, 2002 Mar 9, 2002 ––Jan 11, 2004Jan 11, 2004DataData--set presented hereset presented here††
Jan/Feb 2003Jan/Feb 2003
Mar 9 Mar 9 –– Oct 6Oct 620022002
Jan 2002Jan 2002
DatesDates Live timeLive time(days)(days)
--Electronics upgrade & 20” Electronics upgrade & 20” PMT commissioningPMT commissioning
145.4145.4**Run ARun A(data(data--set of 1set of 1stst paper)paper)
--Start data takingStart data taking
* Was
145
.1 w
ith
old
analys
is
†† T.ArakiT.Araki et al,et al, arXiv:heparXiv:hep--ex/0406035 Jun 13, 04ex/0406035 Jun 13, 04submitted to Phys Rev submitted to Phys Rev LettLett
SSI 2004 Experimental Neutrino Oscillations - Gratta 37
z
VertexingVertexing is performed using timing from the 17” PMTsis performed using timing from the 17” PMTs
-65 (1.1MeV)-68 (1.0MeV)
-60 (2.6MeV)Am/Be(~8MeV)
SSI 2004 Experimental Neutrino Oscillations - Gratta 38
Tagged Tagged cosmogenicscosmogenics can be used for calibrationcan be used for calibration
1212BB
1212NN
Fit to data shows that12B:12N ~ 100:1
τ=29.1msQ=13.4MeV
τ=15.9msQ=17.3MeV
µ
SSI 2004 Experimental Neutrino Oscillations - Gratta 39
Energy calibration uses discrete Energy calibration uses discrete γγ and and 1212B/B/1212NN
68Ge
65Zn
60Co
n-p
Carefully include Carefully include BirksBirks law, law, CherenkovCherenkov and light absorption/opticsand light absorption/opticsto obtain constants for to obtain constants for γγ and and ee––type depositionstype depositions
n-12C
σσ/E ~ 6.2% at 1MeV/E ~ 6.2% at 1MeV
SSI 2004 Experimental Neutrino Oscillations - Gratta 40
Estimate of total volume and Estimate of total volume and fiducialfiducial fractionfraction
SSI 2004 Experimental Neutrino Oscillations - Gratta 41
neutronsneutrons
Fraction of volume Fraction of volume insideinside the the fiducialfiducial radius verifiedradius verifiedusing using µµ--producedproduced 1212B/B/1212N and n (assumed uniform)N and n (assumed uniform)
1212B/B/1212NN
SSI 2004 Experimental Neutrino Oscillations - Gratta 42
-- RRpromptprompt, delayed, delayed < 5.5 m< 5.5 m-- ∆∆RRee--nn < 2 m< 2 m-- 0.5 0.5 µµs < s < ∆∆TTee--nn < 1 ms< 1 ms-- 1.8 MeV < 1.8 MeV < EEdelayeddelayed < 2.6 MeV< 2.6 MeV-- 2.6 MeV < 2.6 MeV < EEpromptprompt < 8.5 MeV< 8.5 MeV
Tagging efficiency 89.8%Tagging efficiency 89.8%
…In addition:…In addition:-- 2s veto for showering/bad 2s veto for showering/bad µµ-- 2s veto in a R = 3m tube along 2s veto in a R = 3m tube along tracktrack
DeadDead--time 9.7%time 9.7%
Selecting antineutrinos, Selecting antineutrinos, EEpromptprompt>2.6MeV>2.6MeV
543.7
ton
543.7
ton5.5 m5.5 m
fiducialfiducial cutcut
Balloon edgeBalloon edge
SSI 2004 Experimental Neutrino Oscillations - Gratta 43
2.52.5Antineutrino spectrumAntineutrino spectrum0.20.2Antineutrino xAntineutrino x--sectionsection
1.01.0Fuel compositionFuel composition0.010.01Time lagTime lag
1.61.6Cuts efficiencyCuts efficiency
2.12.1Reactor Reactor PPthermalthermal
0.060.06Live timeLive time
4.24.2FiducialFiducial fractionfraction
%%SystematicSystematic
6.56.5TotalTotal
2.32.3Energy threshold Energy threshold
2.12.1Scintillator volumeScintillator volume
SSI 2004 Experimental Neutrino Oscillations - Gratta 44
Inconsistent with simple 1/RInconsistent with simple 1/R22 propagation propagation at 99.995% CLat 99.995% CL
Observed events 258No osc. expected 365±24(syst)Background 7.5±1.3
ResultsResults
(Observed(Observed--Background)/Expected = 0.686Background)/Expected = 0.686±±0.044(stat)0.044(stat)±±0.045(syst)0.045(syst)
Caveat: this specific number does not have an absolute meaning iCaveat: this specific number does not have an absolute meaning in n KamLANDKamLAND, , since, with oscillations, it depends on which reactors are on/ofsince, with oscillations, it depends on which reactors are on/offf
766.3 766.3 tonton··yryr
SSI 2004 Experimental Neutrino Oscillations - Gratta 45
2003 saw a substantial dip in reactor antineutrino flux2003 saw a substantial dip in reactor antineutrino flux
SSI 2004 Experimental Neutrino Oscillations - Gratta 46
90% CL90% CL
Good correlation with reactor fluxGood correlation with reactor flux
Expected fo
r no o
scilla
tions
Expected fo
r no o
scilla
tions
(But a horizontal line still gives a decent fit with χ2=5.4/4)
Fit constrainedFit constrainedthrough knownthrough knownbackgroundbackgroundχ2=2.1/4
~0.03 for~0.03 for3TW3TW
hypotheticalhypotheticalEarth coreEarth corereactorreactor
SSI 2004 Experimental Neutrino Oscillations - Gratta 47
Energy spectrum now adds substantial informationEnergy spectrum now adds substantial information
Best fit toBest fit tooscillations:oscillations:
∆∆mm22=8.3=8.3··1010--55 eVeV22
sinsin2222θθ=0.83=0.83
StraightforwardStraightforwardχχ22 on the on the histohisto
is is 19.6/1119.6/11
Using equalUsing equalprobability binsprobability binsχχ22//dofdof=18.3/18=18.3/18
(goodness(goodnessof fit is 42%)of fit is 42%)
A fit to a simple rescaled reactor spectrumA fit to a simple rescaled reactor spectrumis excluded at 99.89% CL (is excluded at 99.89% CL (χχ22=43.4/19)=43.4/19)
SSI 2004 Experimental Neutrino Oscillations - Gratta 48
∆∆mm22=8.3=8.3··1010--55 eVeV22
sinsin2222θθ=0.83=0.83
LMA2 excludedLMA2 excludedat 99.6% CLat 99.6% CL
UnUn--binned likelihood fit to 2binned likelihood fit to 2--flavor oscillationsflavor oscillations
““LMA0” disfavoredLMA0” disfavoredat 94% CLat 94% CL
All solar All solar ννexperimentsexperiments
SSI 2004 Experimental Neutrino Oscillations - Gratta 49
A shapeA shape--only fit givesonly fit givessimilar resultssimilar results
∆∆mm22=8.3=8.3··1010--55 eVeV22
sinsin2222θθ=0.98=0.98
SSI 2004 Experimental Neutrino Oscillations - Gratta 50
KamLANDKamLAND uses a range of L and uses a range of L and it cannot assign a specific L to each eventit cannot assign a specific L to each eventNevertheless the ratio of detected/expectedNevertheless the ratio of detected/expected
for Lfor L00/E (/E (or 1/Eor 1/E) is an interesting quantity, as it decouples) is an interesting quantity, as it decouplesthe the oscillation patternoscillation pattern from the reactor energy spectrumfrom the reactor energy spectrum
no oscillation expectationno oscillation expectation
HypotheticalHypotheticalsingle 180kmsingle 180km
baselinebaselineexperimentexperiment
SSI 2004 Experimental Neutrino Oscillations - Gratta 51
More exotic, nonMore exotic, non--oscillations models for the antineutrinooscillations models for the antineutrinochannel start being less favored by datachannel start being less favored by data
DecayDecay**
excluded atexcluded at95% CL95% CL
DecoherenceDecoherence††
excluded atexcluded at94% CL94% CL
*V.Barger et al. Phys. Rev. Lett. 82 (1999) 2640†E.Lisi et al., Phys. Rev. Lett. 85 (2000) 1166
SSI 2004 Experimental Neutrino Oscillations - Gratta 52
Combined solar Combined solar νν –– KamLANDKamLAND 22--flavor analysisflavor analysis
Includes (small) matter effectsIncludes (small) matter effects
07.009.040.0tan
105.06.02.8
122
25212
−+=
×−+=∆ −
θ
eVm
SSI 2004 Experimental Neutrino Oscillations - Gratta 53
…it took 35 years… but we have:…it took 35 years… but we have:1)1) detected neutrinos from the sundetected neutrinos from the sun2)2) found that part of the neutrino flux is missingfound that part of the neutrino flux is missing3)3) found that only found that only ννee are missingare missing4)4) found that matter effects in the sun (MSW effect)found that matter effects in the sun (MSW effect)
are responsible for the deficitare responsible for the deficit5) found that neutrinos have finite masses (required5) found that neutrinos have finite masses (required
for MSW)for MSW)6) identified mixing parameters 6) identified mixing parameters ∆∆mm1212
22, , θθ12127) found that we can reproduce this effect artificially7) found that we can reproduce this effect artificially
with vacuum oscillations with the same with vacuum oscillations with the same ∆∆mm121222, , θθ1212
8) found that 8) found that νν and antiand anti--νν behave the same waybehave the same way9) found that flavor mixing works better than other9) found that flavor mixing works better than other
scenarios (e.g. decay)scenarios (e.g. decay)10) found that our model for the sun (SSM) works10) found that our model for the sun (SSM) works
very wellvery well
SSI 2004 Experimental Neutrino Oscillations - Gratta 54
The otheroscillations:Atmosphericneutrinos
Higher energyphenomenon
Measurementsdominated by
SuperK
SSI 2004 Experimental Neutrino Oscillations - Gratta 55
SuperKamiokande:the largest “artificial”
water Cerenkov detectorever built (50 kton)
SK1 1996-2001>11146 50cm PMTs40% photocathode
22.5kton fiducial mass
2003-20055182 PMTs recovered
19% photocathodeK2K beam
2006-…Original PMT coverage
T2K beam
SSI 2004 Experimental Neutrino Oscillations - Gratta 59E.Kearns, Nu2004
The oscillatory pattern is now also visible with atmospheric neutrinos
And flavor oscillationis favored over other
models fordisappearance
SSI 2004 Experimental Neutrino Oscillations - Gratta 60E.Kearns, Nu2004
Parameter regions fit by different channels nicely overlap
A 3 flavor analysisfavors νµ-ντoscillation as
responsible forthe atmosphericneutrino anomaly(more on this
later…)
SSI 2004 Experimental Neutrino Oscillations - Gratta 61
Again, the quest is open to observe the oscillationphenomenon with artificial neutrinos
• 12 GeV KEK protons• Mini-K (1kton water + other detectors)
near detector (100m) 1011 νµ every 2.2s• Super-K at 250km 106 νµ every 2.2s (detect ~1event/2days)• 8.9·1019 p.o.t. collected in ~3.5 yrs
SSI 2004 Experimental Neutrino Oscillations - Gratta 62T.Nakaya, Nu2004
In the 3.5 yrs of datathe atm nu backgroundin the KEK beam spillwindow is 10-2 events
Although rate is lowbackground greatly
reduced by beam spilltiming (0.83 ms delay,synchronized offline
using GPS)
-4 -2 0 2 4Tdiff(µs)
104
103
102
10
1
15
10
5
0
SSI 2004 Experimental Neutrino Oscillations - Gratta 63T.Nakaya, Nu2004
Expected no oscillation rate: 6.110.109.150 +
−
no oscill,floating
normalization
K2K establishes:
• νµ disappearance at 2.9σ(standard physics
has 0.33% CL)• Eν spectral distortion at 2.5σ
(standard physicshas 1.1% CL)
Combined we have a 3.9σ effect(standard physics has 0.011% CL)
SSI 2004 Experimental Neutrino Oscillations - Gratta 64T.Nakaya, Nu2004
approximate90% CL
from globalSK fit to
atmosphericneutrinos
SSI 2004 Experimental Neutrino Oscillations - Gratta 65
What we have discovered:What we have discovered:
There is mixing involving νe with best fit at ∆m2=8.3·10-5 eV2 and θ=32° (solar/KamLAND)
There is also mixing involving νµ with best fit at∆m2=2.7·10-3 eV2 and θ=45° (atmospheric/K2K)
If there are only 3 neutrino families, since the twomass differences are of different order of magnitude, we expect to find a third ∆m2 similarto the larger of the two above