neutrino experiments: review of recent results
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Neutrino experiments: Review of Recent Results. Junpei Shirai Research Center for Neutrino Science Tohoku University (for the KamLAND Collaboration). Tau04, 8th International Workshop on Tau-Lepton Physics, Nara, Sept.16, 2004. Contents:. Neutrino Oscillation Experiments - PowerPoint PPT PresentationTRANSCRIPT
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Junpei ShiraiResearch Center for Neutrino Science
Tohoku University
(for the KamLAND Collaboration)
Neutrino experiments: Review of Recent Results
Tau04, 8th International Workshop on Tau-Lepton Physics,Nara, Sept.16, 2004.
Contents:
Neutrino Oscillation Experiments
Solar and Reactor Neutrino Results
Atmospheric Neutrino Experiments
Coming experiments
Double beta decay &
Search for neutrino mass
Summary
Neutrino Oscillation Experiments:
Long history (40~50years!) of challenging mass!
Survival probability of :
1sin22sin2 ( ) <1 ?Mij2LL
4E[Source] [Detector]
ij
coscossinsin
=
dE
Solar : SNOReactor : KamLANDAtmospheric : SuperKAccelerator : K2K
Clear evidence of -flavor change;Flavor change of occursdominantly by Oscillation.
does have a Mass!
Mij2=Mi
2 -Mj2)
Oscillation parameters determined by
P()=1 P()
Flavor eigenstates Mass
eigenstates
* Tiny , M=0 (SM)
Solar Neutrino Problem (SNP)
e
e ?[Earth]
4p+2e4He+2e+26.73MeVE
(Pure e flux is generated by thermo-nuclear fusion in the center of the sun!)
flux: Observation < Prediction[SSM][Experiments]
[Sun]
ppde pepd
pdHe
He HHe 2p
He HBe
He pHe e+
Neutrino generation & spectrum [SSM]
Be eLi
Li p2He
Be pB
BBe* e+ 24He
pp ( .909)
7Be () 8B ()
pp-chain(98.4%) +CNOcycle(1.4%)
J.N.Bahcall
Flu
x@1A
U(/
cm2 /
s/M
eV),
(/c
m2 /
s fo
r li
nes
)
pep ()
hep()
Kamio-kande, SuperKSNO
8B only7Be &above
pp &above
Establish Solar- deficit
‘60
‘70
‘80
‘90
‘00
Homestake
Kamiokande
SuperK
Solar experiments
+e+e
+e+e
[H2O]
[H2O]
e+71Ga71Ge+eGallex/ SAGE
‘83~’96
‘96~
e+dp+p+e+d n+p+N+e+e [D2O]
obs/[SSM]
0.5‘68~
‘90~’01‘91~’97
SNO ‘99~
RadiochemicalReal time
(PDG’04)
0.40.3 0.6
GNO
e only
e++
e+37Cl37Ar+e[C2Cl4]
First observationof solar
really comes from the sun
Detection of pp
High Precision measurement
Active Non-e Components !
PRL 89, 011301(‘02) First evidence of Active Non-e component.
Clear deficit of e): Excellent agreement with SSM.
Oscillation looks very promising, but several solutions of M2 and for SNP!
e+dp+p+e
+d n+p+
+e+eSNO
SSM=5.05+1.010.81e)=1.76±0.06(stat) ±0.09(sys)
=5.09+0.44 (stat)+0.46
(sys)0.43 0.43
(106cm2s)
CC /NC= e(e++ )
CC /ES= e[e+0.154(+ )]
n+d H+(6.25MeV); 0.5mb (~’01)n+Cl Cl+’s(8.6MeV); 44b (~’03)n+He p+H; 5330b, event/event (’04~)
Neutron detection ;
(106cm2s)
-Oscillation parametersFour solutions to SNP
VAC(just so)
Matter effect (MSW effect)
P(ee)=1sin22sin2(M2L/4E)
M2sin22 22EGFNe cos2
sin22
SMA, LMA, LOW by
LMA looks very promising, but no single experiment uniquely determined the solution.
Needs decisive experiment !
H.MurayamaAllowed region(95%)
Seasonal variation, D/N asymmetry, Energy Spectrum ;
e only]
Man-made provided by Reactor.
Reactor neutrino experimentsLong history since the first detection of neutrino by F.Reines and C.L.Cowan using a reactor in 1950s.
n
n
AX
Y
Neutron rich nuclei to decay.
e emission
Power reactorsas a source.
+ ~200MeV/fission
235U, 239Pu,241Pu, 238U
Typical reactor : 3GW(thermal energy) !
Pure and intense flux which is known < 2% !Measure P(ee) with a distant detector.
Previous reactor results
Intense e source & Large Detector are crucial! KamLAND
No oscillation was found!
EdM2>10 eV2
M2~105eV2 to check LMA,Loscil= M2
(epe+n)
e interactions
e flux
E(MeV)
e spectrum of each fuel elementis experimentally known or calculated (~2%).
2E ~O(100)km
Threshold(1.8MeV)
e flux, and interaction energies
6 84 5 73
KamLAND Experimental Area
2.2km
1000m SuperK
Nitrogen Gas System
Control RoomDetector
Oil Purification System
Water Supply System
Kamioka mine
~70GW(thermal) within175±35km from KamLAND.7% of the total reactor power in the world !
2700m w.e.~0.3 ’s/sec
1000ton Ultra pure LSin a 13m Balloon
KamLAND Detector
PMTs (in 2.5m thickmineral oil;1325 17”(t~1.5ns)+554 20”() E/E~7.3%/E[MeV]
Water Cherenkov counter(225 20”PMTs)
~106 e/cm2/sec @KamLAND
KamLAND
52 power reactors in Japan
(E>1.8MeV)
(Kamioka Liquid scintillator Anti-Neutrino Detector)
20m
235U
239Pu
238U241Pu
Reactor Neutrino flux at KamLANDThermal Power
Burnup
Typical reactor operation
1106 e/cm2/sec (E>1.8MeV)
Wakasa Bay
KashiwazakiOthers
HamaokaShika
Korea
Total
is precisely estimated within ±3.4%
Fission rates are calculatedby thermal power and initial fuel composition.
Fission Rates
Reactor power 2.1%, Fuel comp.1.0%-spectra 2.5%
Mar’02Jan’04
e Detection:Traditional method since F.Reines used Liquid Scintillator as an active target !
e
pe+ e
n
p
d
(0.51)
(0.51)
(2.2)
[Prompt e+ signal]
[Delayed by neutron capture]Correlated signals;
(Energy, Position, Time)
Greatly removes backgrounds!
[E1.8MeV]
e; ID, E, time, position
Ee+(=E0.8MeV)
eeeerecisely known (0.2%)
~200s
epe+n
KamLAND:Vertex and Energy Calibration
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-ray sources along the central z-axis
12B/12N68Ge,60Co,65Zn
n pn12C
Off axis by-spallation
±2%
±5cm
E/E
Fid vol.(R<5.5m)
Z-position
Z--
devi
atio
n(cm
)
(R/6.5m)3
12B/12N(4~15MeV)
(Nfid/Ntot)/(Vfid/Vtot)Total vol.Energy dependence
Fiducial
Fiducial vol. Error = 4.7%Energy threshold(2.6MeVPrompt signal) = 2.3%
KamLAND: Event Selection
Correlated events :
0.5s<T<1msR<2mEdelay=1.8~2.6MeVEprompt-e+=2.6~8.5MeV
Reject geo-
Time, Distance &Energy of Delayed events
Fiducial cut: R[prompt], R[delayed]<5.5mReject -spallation (9Li/8He rejection): 3m cylinder from the Whole detector
Prompt event
Delayed event
New Analysis!* Data sample:766.3 ton yr (Mar.9,‘02~Jan.11,‘04)4.7 times larger statistics than the 1st results
RFid=5.5mRBalloon=6.5m
[showering [non-showering ]
9Li/8He bkg: 4.8±0.9 events
Results
2.6MeV
Observed e : 258Expected for non-oscillation : 365±24Background : 7.5±1.3
9Li/8He: 4.8±0.9Fast neutrons: <0.89Accidental: 2.69±0.02
[>2.6MeV]
analysis region
sin22 = 0.83m2 = 8.3×10-5 eV2
Best-fit oscillation parameters
2.6MeV
(Nobs-Nbkg) NExpected
= 0.686±0.044±0.045(stat) (sys)
Clear disappearanceat 99.995%CL
Scaled No-oscillationExcluded at 99.9%CL
Combined : 99.99996%
Null Oscillation Hypothesis disfavored
2.6MeV
(Nobs-Nbkg) NExpected
= 0.686±0.044±0.045(stat) (sys)
Clear disappearanceat 99.995%CL
Observed e : 258Expected for non-oscillation : 365±24Background : 7.5±1.3
9Li/8He: 4.8±0.9Fast neutrons: <0.89Accidental: 2.69±0.02
[>2.6MeV]
No-oscillationResults
L/E plot to check Oscillation or other hypotheses
Decay : cos2+sin2exp[mL/(2E)]Decoherence : 1(1/2)sin2 2exp[L/E]
Excluded at
96.5%
98.3%Neutrino Oscillation isthe best to fit the data!!
Excluded at
Barger et al.,PRL82,(‘99) 2640
E.Lisi et al.,PRL85,(‘00) 1166
Best Fit Oscillation
Oscillation Analysis with 2 flavors
Solar LMA
Best fit (in LMA1)sin22=0.83m2=8.3105
New results
1st results
Best fitsin22=1.0m2=6.9105
PRL 90, 021802(2003)
LMA2: excluded at 99.6%CL
LMA0: excluded at 94%CL
210Pb210Bi210Po +13C n+16O*(6.13, 6.05)22.3y 138d
222Rn
5d206Pb (stable)
5.4MeVprompt delayed
3.8d
A New Background source (,n) !
n+12C 12C*(4.4) +n npd
Excluded(95%)
Excluded(95%)
LMA
Possible background sources;(,n), spontaneous fission of 238U,NC reaction by atmospheric ,NC reaction by solar on deuterons
Global Analysis of KamLAND+ Solar
Mass difference
tan2=0.40+0.09
m2=8.2+0.62eV2
Mixing angle
Preliminary
New 13C(,n)16OBackground ~10events
KamLAND has shown decisively oscillation of LMA and M2 has been measured very precisely!!
2004)
SK Atmospheric neutrino oscillation
Zenith angle distributionSK-I (1496days; 1996-2001):
e-like -like -like
Up-goingstopping
through
cos
cos
cos
cos
Up Down
Oscillation explains quite wl !Strongly disfavored null oscillation!
E.Kearns(2004)
Best-fit & Contours
SuperK L/E AnalysisSelect events with best L/E resolutionTo observe oscillation pattern!
2726 events by a cutof 70% resolution
decay decoherence
Decay rejected at 3.4 Decoherence rejected at 3.8
SK-1 L/E Analysis
SK-1 All Data
K2K
oscillation, dip at ~500km/GeV
Further constraint on m2
m2=(1.9~3.0)103eV2
sin22>0.90 at 90%CL
Best fit: (sin22m2)=(1.02, 2.4 103eV2 ), 2=37.7/40 dof
Other L/E resolutionDifferent binning of L/EChange of the direction vectorE-like event
Dip: checked by
13 and CP in lepton sector
e
3 mixing angles; 12, 23, 13
Three Mass differences; M213~M2
23>>M212
CP-violating phase
Atmospheric K2K
New challenge !!
Reactor Solar
cij=cosij
sij=sinij
Reactor and LBL-Accelerator approaches are complementary!
* Present limit: sin2213<0.12(CHOOZ)
e
c23
s23s23
c23
1 0 0
00
c13
0s13ei
c1210 s13e-i
00c13
0s12
1
0s12
00
c12
=1
PMNS-matrix
Reactor & LBL-accelerator experiments.
Reactor : P(ee)
c134sin2212sin212 s12
2sin2213sin232 c122sin2213sin231
ij(Mi
2Mj2)L
4E
Reactor , L~O(1)km
P(ee)=1 sin2213
to make sin232,
Accelerator : P(e)= sin2213sin223sin232
~1 (taking L~2E/M322)
2 M23
2
M122
cos13sin212sin223sin213sin
cij=cosij , sij=sinij
[Pure 13 measurement !]
~0.04
LBL & Reactor
0
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0 0.02 0.04 0.06 0.08 0.1 0.12 0.140
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0 0.02 0.04 0.06 0.08 0.1 0.12 0.14
Reactor Measurement
LBL-Accelerator.Measurement
sin2213
P(
e
)
sin223={1±1-sin2223}/2
Intrinsic uncertainty from sin223
0.390.61
sin213sin
LBL-accelerator experiment alone;
and sinambiguity to determine sin2213
Reactor 13 measurement solves them. sin2213 provides the observability of the .
ex) sin2223 =0.95 (Lower lim. SK) sin223 =0.61, 0.39
7 reactors
2 Near detector
Far detector
Kashiwazaki Nuclear Power Plant (Japan);24.3GW(World’sLargest thermal power!)
~400m
1300~1800m
0
1
2
3
4
5
6
-1
-2
-3
-4
7p
LS
Gd-LS(8.5ton)
6m
Gd-LSepe+n
promptDelayed(~30s)
’s~8MeV(Gd)
[Detector]Depth: 200m(far), 70m(near)
Non-Gd LSSys. Error 0.5~1%(<1%(det)+ 0.2%(flux))
Sensitivity: sin2213~0.017-0.026
40,000events/2yr (Far det.)
Buffer oil
Kaska: Reactor 13 measurement
Search for decays
e e
W W
A(Z) A(Z+2)+2e +2e (L=2)
Majorana
(T)=G|M|2 |<m>|2
Nuclear Matrix element
Phase space factor
|<m>|=|Uei2mi|=|m1c12
2c132+m2s12
2c132e2i +m3s13
2c132e2i|
3
i=1
It is related to the neutrino mass scale.Mass hierarchy; m1m2m3 [NH], m1m2m3 [IH], m1m2m3 [QD]
is very important. If found, L=2 process, Majorana neutrino, |<m>|constrains neutrino mass patterns !!
Effective Majorana mass
A(Z) A(Z+2)
Nuclear process
cij =cosij, sij =sinij
Majorana CP phase
1Sensitivity of
would make a breakthrough !
|<m>| & mass hierarchyE
ffec
tive
mas
s |<
m
>| (
eV)
0.01
0.10
1.00
0.001
1.000.100.0100.001Minimum neutrino mass (eV)
PDG’04
Degenerate
Inverted Hierarchy
Normal Hierarchy
Mass pattern and minimum mass
sin2solm2sol~5meV
m2atm~50meV
m1~m2~m3
m1~m2>m3
m1~m2<m3
|<m>|=|m1c122+m2s12
2e2i
+m3s132c13
2e2i|
0
|<m>| > a few10meV Inverted hierarchy
appears as a sharp peak at the highest energy of the 2 spectrum in decays.
Sensitivity (Lower limit of T1/2[y])
BM t E
# of nuclei=(M/A)NAa
Background rate; counts/kg/KeV/yEnergy resolution;KeV
[BG][Signal]
A; atomic weight, a; AbundanceM; Total mass [kg]
T1/2 A
a M tBE
running time; y
|<m>|=[T
1/2G|M|2]1/2
1
Q5
Detection efficiency
(T1/2 /ln2)
N t
Key for Search
Lots of Challenges to 0
Scintillation
CryogenicsCUORE/CUORETINOCOBRAGEMGENIUSMajoranaMPI
CAMEOCANDLESCARVELGSOXe
DCBAMOONNEMOEXO
Tracking
113Cd, 123Te
76Ge116Cd
48Ca116Cd
160Gd136Xe
150Nd100Mo
82Se136Xe
Crystals in Liq. Scint.
Foils in wire chamber,TPC, Mag. fieldIonization (LN2)
Bolometory
a MBE , Q
Making large figure of merit
to reach |<m>|~100-10 meVin several years operation!
Direct mass measurement
Use only kinematics of decay particles to measure missing mass. (cf. -oscillation, , astrophysics)The fact of large flavor-mixing of Properties of ’s (incl. mass) might be the same. Mass degeneracy can be checked with a sensitivity of sub-eV.
Tritium -decay has been tried : Small endpoint energy (18.6keV) Super-allowed transition Final state spectrum of daughter molecules are well known.
Troitsk m<2.05eV(@ 95%CL)Mainz m<2.2eV (@ 95%CL) PLB460(‘99)219.
PLB350(‘95)263.
m=0
m0
E0-Ee E0
dN/dEe=KF(Ee,Z)peEtot(E0-Ee)[(E0Ee)2m2)]2
Both uses magnetic-bottle spectrometer and gaseous 3H target.
dN/d
E
KATRIN (Karlsruhe Tritium NeutrinoExperiment)
Electrostatic spectrometer with Adiabatic magnetic collimationWindowless gaseous tritium source
Large acceptance, High resolution
=Etrans/B : conserved in adiabatic B fieldE/E=Banal/Bmax : Energy resolution (Banal ~a few mT, Bmax~6T)
~70 m beamline, 40 s.c. solenoids
Stainless steel vessel(10m
-mass sensitivity: 0.2eV
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Needs confirmation by coming experiments!
Degenerate!
Highest Sensitivity,Select single site events by PSA
(H.V.Klapdor-Kleingrothaus,2004)
A claim for discovery of
Can be found by direct measurement with sub-eV sensitivity and planned 0 experiments!
SummaryRecent experiments have established oscillation by observing the flux deficit, flavor change and spectral distortion; Solar (SK/SNO)/Reactor (KamLAND) for e (e), Atmospheric (SK)/Accelerator (K2K) for
Oscillation parameters, 12, 23, M122, M 23
2 are being determined precisely by ongoing experiments.
Reactor 13 measurement is very important to the coming LBL experiment aiming to measure CP-violating phase
experiment is crucial not only to know whether , but constrain or determine mass pattern, if |<m>| sensitivity to ~0.01eV is attained.remass search with a mass sensitivity of sub-eV can havea discovery potential.
Backup slides
M0
Solar problemAtmospheric anomaly
oscillation !
Absolute mass?Mass pattern?CP & Mixing mechanism?
Precise measurement ofoscillation parameters.Planned , LBL experiments
1000ton D2O in 12m acrylic vessel9600 PMTs (60%of 4)
H2O (1700ton inner shield +5300ton outer shield)
Deep underground 6010m w.e.
Urylon Liner and Radon Seal
Sudbury Neutrino Observatory