KEK - Reactor Neutrino Oscillations: KamLAND and KASKA · 2012. 10. 19. · 0.8 1 data/model...

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


Contents

* Neutrino Oscillation * KamLAND Observation of Reactor Neutrino Oscillation * KASKA Reactor q13 Project

(KamLAND observation of geo-neutrinos)* Summary


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


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


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


KamLAND Experiment


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.


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)


Reactor Neutrino Oscillation


Distance to the reactors

68GWth

L=180 35km+-


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%


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


nep cross section


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.


Event Display: Low Energy Event

(Enomoto WIN05)


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)


Neutrino Event Spectrum

Probability of No Deficit =0.002%Probability of No Distortion=0.4%

258events

17.8events

365.2events expected

Background


Distortion Pattern

Oscillation back

†

Pn Æn =1- sin2 2qsin2 Dm2

4Ê

Ë Á

ˆ

¯ ˜

LEn

Ê

Ë Á

ˆ

¯ ˜

(Enomoto WIN05)


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!!


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:


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.


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


..... to measure q13

A reactor q13 experiment at Kashiwazaki-Kariwa Nuclear Power Station

KASKA Project


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


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


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


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


Detector & Shaft Hole

n target:10t Gd loaded liquid scintillator


detector 3D fig


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

EgÂ ~ 8MeV

30μs

prompt signal

Delayed signal

(3) 1μs<ΔT <200μs

&No Fiducial Cut

Efficiency is insensitive to cuts


Systematics


Expected Sensitivity

10 times better sensitivity than current limit& Comparable to Accelerator q13.


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


Possible ExtensionKASKA as a front detector for optimized q12

50km

KamLAND

50km

KASKA

Most precise q12 measurementwill be possible.

KamLAND size detector


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


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


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


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.


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.

KEK - Reactor Neutrino Oscillations: KamLAND and KASKA · 2012. 10. 19. · 0.8 1 data/model...

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