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05.10.03 suekane@Radcor2005 1
Reactor Neutrino Oscillations:
[email protected], Tohoku University
7th International Symposium on radiative corrections 2005.10.03
KamLAND and KASKA
05.10.03 suekane@Radcor2005 2
Contents
* Neutrino Oscillation * KamLAND Observation of Reactor Neutrino Oscillation * KASKA Reactor q13 Project
(KamLAND observation of geo-neutrinos)* Summary
05.10.03 suekane@Radcor2005 3
Neutrino OscillationIf flavor eigen states and mass eigen states mix,
†
ne
nm
Ê
Ë Á
ˆ
¯ ˜ =
cosq sinq
-sinq cosq
Ê
Ë Á
ˆ
¯ ˜
n1
n2
Ê
Ë Á
ˆ
¯ ˜
†
ne fi cos2 qe-iE1t + sin2qe-iE2t( ) ne + sinq cosq e-iE2t - e-iE1t( ) nm
†
Pne Ænm
m<<Eæ Æ æ æ sin2 2qsin2 Dm2L4En
Wavelength => Dm2=m22-m1
2
Amplitude => sin22q
0
0.2
0.4
0.6
0.8
1
1.2
0 50000 100000 150000 200000 250000 300000
X(m)
Probability
ne
nm
L
05.10.03 suekane@Radcor2005 4
Kajita Fufact04
nm -> nx Oscillation
Atmospheric nm oscillation by Super Kamiokande group 1998
At least one neutrino is heavier than 0.05eV!!
Long Baseline Accelerator experiment by K2K group
†
P nm Æ nm( )
†
sin2 2q23 ~ 1Dm23
2 ~ 2.4 ¥10-3eV 2
Ï Ì Ó
05.10.03 suekane@Radcor2005 5
ne -> nx Oscillation
0
0.2
0.4
0.6
0.8
1
data/model
HomestakeGNO+GALLEX SAGE SuperKamioka
太 ニュートリノflux
deficit of ne flux
Solar n problem
†
sin2 2q12 ~ 0.8Dm12
2 ~ 10-4 eV 2
Ï Ì Ó
But is it really true?Need to check with man-made n
but ne+nm+nt flux is as expected
05.10.03 suekane@Radcor2005 6
KamLAND Experiment
05.10.03 suekane@Radcor2005 7
KamLAND Detector
Cosmicray veto
Balloon
S.S. tank
PMT
Liquid Scintillator
buffer oil
Electronics
The Largest and Lowest-BKG
n e detector in the world.
05.10.03 suekane@Radcor2005 8
A brief history of KamLAND
Detector Construction 1997~Start Data Taking 01/20021st reactor paper (deficit) 12/2002 (PRL 90:021802,2003)
Solar ne search 10/2003 (PRL 92:071301,2004)
2nd reactor paper 06/2004 (PRL 94, 081801,2005)
(spectrum distortion)Geo-neutrino paper 07/2005 (Nature 436:499-503,2005)
05.10.03 suekane@Radcor2005 9
Reactor Neutrino Oscillation
05.10.03 suekane@Radcor2005 10
Distance to the reactors
68GWth
L=180 35km+-
05.10.03 suekane@Radcor2005 11
Reactor Neutrino Production
n U235
U236*
n n
Zr94140
Cs
I140
Te140
Xe140
Rb94
Sr94
Y94
e-
e-
e-
e-
e-
e-
ne
ne
ne
ne
ne
ne ~6n/fission & ~200MeV/fission
fl~ 6 ¥1020n e / s / reactor
Neutrino Spectra
En~ a few MeV
spectrum known to 2.5%
05.10.03 suekane@Radcor2005 12
ne detection
n + p Æ d + g 2.2MeV( )
n e + p Æ n + e+
2.2MeV200μs
18MeV
t
Signal Property
e+ signal n signal
e+ + e- Æ 2g
En - 0.8MeV( )
(nep -> e+n); an ideal reaction, because
• Only ne contributes (no background from other neutrino species)• Low threshold Energy (1.8MeV)• Large cross section (~100sne) • p is abundant in LS• Cross section precisely known (ds=0.2%)• ne energy can be measured (En=Evisible+0.8MeV)• Delayed Coincidence -> powerful background rejection
05.10.03 suekane@Radcor2005 13
nep cross section
05.10.03 suekane@Radcor2005 14
If Neutrino Oscillation Exists
†
N En( ) = N0 En( ) 1- sin2 2qsin2 Dm2L4En
Ê
Ë Á
ˆ
¯ ˜
=> Deficit of neutrino events=> Distortion of energy spectrum
Long baseline & Low En=> sensitive to very low Dm2!!
Dm2 =2pEn
L~ 2p ¥ 4MeV
180km~10-5eV 2
LMA region (10-4eV2)can be covered.
05.10.03 suekane@Radcor2005 15
Event Display: Low Energy Event
(Enomoto WIN05)
05.10.03 suekane@Radcor2005 16
Event SelectionDelayed Coincidence: 0.5 < ΔT < 1000μsec ΔR < 200 cm 1.8 < Edelayed < 2.6 MeV
Fiducial Volume: Rprompt < 550 cm Rdelayed < 550 cm
Spallation Cuts: ΔTμ > 2 msec ΔTμ > 2 sec (showering muons) or ΔL > 300 cm (non-showering)
Energy Window: 2.6 < Eprompt < 8.5 MeV
(Mar. 9, 2002 ~ Jan. 11, 2004)(Enomoto WIN05)
05.10.03 suekane@Radcor2005 17
Neutrino Event Spectrum
Probability of No Deficit =0.002%Probability of No Distortion=0.4%
258events
17.8events
365.2events expected
Background
05.10.03 suekane@Radcor2005 18
Distortion Pattern
Oscillation back
†
Pn Æn =1- sin2 2qsin2 Dm2
4Ê
Ë Á
ˆ
¯ ˜
LEn
Ê
Ë Á
ˆ
¯ ˜
(Enomoto WIN05)
05.10.03 suekane@Radcor2005 19
Many reactors stopped in 2002 and 2003
Consistent withEstimated BG
No Oscillation Case
fiPower variation can be used to demonstrate that the n's are coming from reactors!!
05.10.03 suekane@Radcor2005 20
Oscillation Parameters
†
Dm2 = 7.9-0.5+0.6 ¥10-5 eV 2, tan2q = 0.46KamLAND only:
(PRL 94, 081801,2005)
†
Dm2 = 7.9-0.5+0.6 ¥10-5 eV 2, tan2q = 0.40-0.07
+0.10KL+Solar:
05.10.03 suekane@Radcor2005 21
MNS Matrix Now
|s13|<0.2, d: totally unknown
†
~0.9 0.5 s13e
id
0.4 0.6 0.70.4 0.6 0.7
Ê
Ë
Á Á Á
ˆ
¯
˜ ˜ ˜
n1
n2
n3
Ê
Ë
Á Á Á
ˆ
¯
˜ ˜ ˜
†
ne
nm
nt
Ê
Ë
Á Á Á
ˆ
¯
˜ ˜ ˜
=
1 0 00 c23 s23
0 -s23 c23
Ê
Ë
Á Á Á
ˆ
¯
˜ ˜ ˜
c13 0 s13eid
0 1 0-s13e
-id 0 c13
Ê
Ë
Á Á Á
ˆ
¯
˜ ˜ ˜
c12 s12 0-s12 c12 0
0 0 1
Ê
Ë
Á Á Á
ˆ
¯
˜ ˜ ˜
n1
n2
n3
Ê
Ë
Á Á Á
ˆ
¯
˜ ˜ ˜ †
sij = sinqij , cij = cosqij( )
SK+K2K KamLAND+SolarNext ImportantTargets.
05.10.03 suekane@Radcor2005 22
q13: a key to the future
Large q13 OK, Let's proceed to CPV experiments
Small q13 ummm... †
P n m Æ n e( ) - P n m Æ n e( ) ~ sinq13sind
* Detectability of CPV d: depends on q13
†
q13
05.10.03 suekane@Radcor2005 23
..... to measure q13
A reactor q13 experiment at Kashiwazaki-Kariwa Nuclear Power Station
KASKA Project
05.10.03 suekane@Radcor2005 24
The KASKA Project MembersNiigata University: N.Tamura, M.Tanimoto, H.Miyata, H.Nakano T.Kawasaki,M.Katsumata, T.Iwabuchi, M.Aoki, N.Nakajima, K.SakaiTohoku University: F.Suekane, Y.Sakamoto, S.Tsuchiya,Tokyo Metropolitan University: T.Sumiyoshi, H.Minakata, O.Yasuda , K.SakumaTokyo Institute of Technology: M.Kuze, K.Nitta, H.Furuta, J.Maeda, Y.FunakiKobe University: T.HaraKEK: N.Ishihara, H.SugiyamaMiyagi: Y.Fukuda, AkiyamaHiroshima Institute of Technology: Y.Nagasaka
05.10.03 suekane@Radcor2005 25
3 generation Reactor ne disappearance rate
Fij =Dmij
2L4E
Ê
Ë Á
ˆ
¯ ˜
Experiment with ssys<1%, L~1.8km
†
P n e Æ n e( ) =1- 4c132 c13
2 s122 c12
2 sin2F21 + s132 c12
2 sin2F31 + s132 s12
2 sin2F32( )
0
0.2
0.4
0.6
0.8
1
1.2
0.1 1 10 100 1000
L(km)
P(νe -> νe)
sin2 2q13 = 0.1
KASKA
KamLAND
Dm132
Dm122
†
P n e Æ n e( )
=1- sin2 2q13sin2 Dm132
4E
05.10.03 suekane@Radcor2005 26
Concept of Experiment
原子炉
1.8km
0.4km
200m70m
前置検出器
KAKSA検出器
*Powerful reactor complex*Optimized baseline.*Cancel Systematic errors by Near/Far data comparison*Cut insensitive event selection
~150m~50m Reactors
Near Detector
Far Detector
05.10.03 suekane@Radcor2005 27
Near Detectors Far Detector
0 5 10 15 20 25 30
Kashiwazaki-Kariwa(日)
CHOOZ(仏)
DiabloCanyon(米)
Braidwood(米)
DayaBay(中)
Angora(ブラジル)
Krasnoyarsk( )
Site Power (GWth)
Reactor PowerComparison
Kashiwazaki-KariwaNuclear Power Station
7 reactors 24.3GWth
05.10.03 suekane@Radcor2005 28
Detector & Shaft Hole
n target:10t Gd loaded liquid scintillator
05.10.03 suekane@Radcor2005 29
detector 3D fig
05.10.03 suekane@Radcor2005 30
Event Selection
(1) 0.7<Eprompot <9MeV
(2) 5MeV<Edelayed <11MeV
p
νe
e+
e-
γ(0.511MeV)
γ(0.511MeV)
n
Gd
γ
γγ
γ
Eg ~ 8MeV
30μs
prompt signal
Delayed signal
(3) 1μs<ΔT <200μs
&No Fiducial Cut
Efficiency is insensitive to cuts
05.10.03 suekane@Radcor2005 31
Systematics
05.10.03 suekane@Radcor2005 32
Expected Sensitivity
10 times better sensitivity than current limit& Comparable to Accelerator q13.
05.10.03 suekane@Radcor2005 33
Complementality to accelerator q13 measurements
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 0.14†
P nm Æ ne( )ª sin2 2q13sin2q23 - 0.05sin2q13sind
†
P n e Æ n e( )(@L ~1.8km) =1- sin2 2q13
Reactor Measurement
AcceleratorMeasurement
P(n m
->n e
)sin22q13
sin22q23=0.95
sin2 q 23=
0.61
sin2 q 23=
0.39
Cooperation of Accelerator + ReactorNecessary to resolve ambiguityand perform precision measurement
matter effect ignored
05.10.03 suekane@Radcor2005 34
Possible ExtensionKASKA as a front detector for optimized q12
50km
KamLAND
50km
KASKA
Most precise q12 measurementwill be possible.
KamLAND size detector
05.10.03 suekane@Radcor2005 35
Geo NeutrinosNature 436, 28 July 2005
U series:Qheat=49.7MeV
Th series:Qheat=40.4MeVne
ne
ne
ne
ne
ne
ne
ne
ne
ne
ne
05.10.03 suekane@Radcor2005 36
nep threshold
Observation of Geo neutrino fi Abundance and Localization of U and Thfi Thermal Structure and History of the earth - Is the earth cooling or equilibrium state? - What is the future of the earth? - What is the residual heat of the earth formation? - What drives the geo magnetic field?
ne from U/Th/K decay
05.10.03 suekane@Radcor2005 37
Reactor n13C(a,n)16O
238U232Th
Accidental
Expected total backgrounds
Expected total
Observed ne candidates 152 eventsExpected total backgrounds 127±13 events
25+19-18
events
U+Th geo-nCandidates: Rate only
2nd reactor results
Geo-n
BSE model:19 events
05.10.03 suekane@Radcor2005 38
Rate + Shape analysisC.L. contours for detected U and Th geo-ns.
NU+
NT
h
(NU-NTh)/(NU+NTh)
Th/U massRatio=3.9
NU+NThPrediction from theBSE model(19 events) Best fit: 3 U and
18 Th Geo-n's.D
c2 90%CL
4.5 54.2
NNUU++NNThTh::Consistent with predictionConsistent with prediction of geophysical model. of geophysical model. Geo-Geo-nn detection @ detection @95%!95%!
Th/U Mass ratio=3.9
U+T < 60TW (99%CL) U+T < 60TW (99%CL) ConstraintConstraint by direct method! by direct method!
28
Shirai, 05 Lomonov Conf.
05.10.03 suekane@Radcor2005 39
Summary• KamLAND observed the reactor neutrino oscillationand have determined the oscillation parameter to Dm2
12=7.9x10-5eV2, tan2q=0.40combining with solar neutrino results.• KASKA will measure sin22q13 down to 0.015 by 2012if budget request is approved this year.
†
ne
†
nm
Please add this propagator to your diagram.
• KamLAND observed Geo-neutrino for the first time.