Solar Neutrino Results

Tadao Mitsui Research Center for Neutrino Science, Tohoku University

July 26, 20046th International Workshop on Neutrino Factories & Superbeams

Osaka University, Osaka, Japan

Solar and reactor neutrinos

• Results from Super-Kamiokande and SNO

• Reactor results from KamLAND

• Radiochemical results and earlier works

• Near future prospects

(*1)

(*2)

(*1) neutrinograph of the sun by Super-K, (*2) hep-ph/0406294

Chlorine (1964 ~ 1994)

• First solar neutrino observation• Established solar neutrino deficit• 615-ton C2Cl4, e(37Cl, 37Ar)e-

• Final result: 2.56 ± 0.16 ± 0.16 SNU

• SSM (BP04) expectation: 8.5 1.8 SNU• Data/SSM = 0.30 ± 0.03 Still important input in the current

global analysis for solar neutrino

SSM BP04: J.N. Bahcall and M.H. Pinsonneault PRL 92, 121301

0.813 MeV

8B, 7Be

SNU: 1 interaction / sec each 1036 target atoms

Kamiokande (1987 ~ 1995)

• First measurement of time, direction, energy of solar-

• Data/SSM=0.55 ± 0.04 ± 0.07• Upgraded to Super-K

PRD 44 (1991) 2241

7 MeV

8B

Gallium experiments

• Sensitive to pp neutrino (main component of solar-)• e(71Ga, 71Ge)e-

• 68.1 ± 3.75 SNU (GALLEX + GNO + SAGE)• SSM (BP04): 131+12

-10 SNU• Data / SSM = 0.52 ± 0.03

0.233 MeV

pp, 7Be, 8B

(*1) C.M. Cattadori, Neutrino 2004

new results (*1)

Four solutions that were allowedonly with fluxes (Cl, Ga, Kamiokande)

(LMA) Mikheyev-Smirnov- Wolfenstein (MSW)

~106 range in m2

Super-Kamiokande (1996 ~ ) • 50 kton water cherenkov• 22.5 kton fiducial• ~ 15 events / day (> 5 MeV) ( 8B, (hep) )

+ e- + e-

well remembers energy, direction

Super-Kamiokande-I (1496 days)

M. Nakahata, Neutrino 2004, PLB 539, 179

May 31, 1996 - July 13, 2001

Super-Kamiokande-I (1496 days)

M. Nakahata, Neutrino2004, PLB 539, 179

May 31, 1996 - July 13, 2001

SK-I: energy and zenith angle 2-D spectrum“zenith spectrum”

Excluded without8B flux (rate)

PLB 539, 179

Allowed(with SSM 8B flux)

SMA, Just-so: excluded by energy spectrum

LOW, LMA: constrained by day/nightExpected “regeneration” of e during night: too largecompared with the data

• Asdf

Only LMA at 98% C.L.

PLB 539, 179

May 2002

Ga + Cl + SK + SNO rates + SK zenith spectrum

Sudbury Neutrino Observatory (SNO)1999 ~

1000 ton D2O

12-m diameteracrylic vessel

1700 ton H2O

Support structurefor 9500 8-inch PMTs

5300 ton outer H2O

• CC = e

• NC = e + +

= (all active )• ES = e

+ 0.154 ( + )

• Determine e, + 1 redundancy

e + d p + p + e-

e + d p + n +

e + e- e + e-

CC: charged current

NC: neutral current

ES: elastic scattering (also SK)

n + d 3He + 6.25-MeV (phase I)

energy,(direction)

energy,direction

Unique sensitivity to neutrino flavor

Results: extraction of 3 reactions

CC: 1967.7+61.9 eventsNC: 576.5+49.5 eventsES: 263.6+26.4 events

cos sun

Vertex Energy

PRL 89, 011301, results from 306.4 days

- 25.6

- 48.9

- 60.9

SK-ES + SNO-CC: 3.3

PRL 87(2001), 071301

SK-ES + SNO-CC,NC,ES: 5.5 PRL 89(2002), 011301

With SNO-phse-II (salt) dataM. Nakahata, NOON2004

Evidence for flavor transformation

Significance for non-zero

BP04 = 5.79 (±23%)

SSM “verified”

Deduced “appearance”

Only LMA at 99.5% C.L.

-ADN = 7.0 % 4.9% %+1.3- 1.2

July 2002

PRL 89, 011302

SNO day/night spectra + all solar

from day/night spectral shape analysis

• Reactor e experiment• To reach solar- solution 100 improvement on m2 sen

sitivity

1100

ChoozPalo Verde

100

LMA

A. Suzuki, Neutrino 98

KamLAND

Powerful commercial reactors

First results from KamLANDPRL 90, 021802

e disappearance:99.95 % C.L.

Dec. 2002

Impact of KamLAND

assuming CPT invariance

http://hitoshi.berkeley.edu/neutrino/

LMA-I and LMA-IIfrom spectral shape analysis

95 % C.L.

PRL 90, 021802

LMA-II:m2~1510-5 eV2

LMA-I:m2~710-5 eV2

LMA: precise studySK-I reanalysis: un-binned (time, energy)

• To use all information of zenith angle dependence during night

• Un-binned maximum likelihood method for time and energy

PRD 69, 011104 (R)

m2=6.310-5 eV2, tan2=0.55

Sept. 2003

Consistent results

Binned (PLB 539, 179)

Un-binned (PLD 69, 011104)

Day/night: statistical error 25% reduced

Binned (PLB 539, 179) Un-binned (PLD 69, 011104)

ADN = - 2.1 % 2.0% %+1.3- 1.2 ADN = - 1.8 % 1.6% %

+1.3- 1.2

(at best fit LMA)

LMA-I LMA-II

expected

observed(± 1)

LMA-II disfavored

After SK un-binned analysisLMA-II is excluded at >95 % C.L.

Sept. 2003All solar

M. Nakahata, Neutrino 2004

All solar + KamLAND 1st result

PRD 69, 011104 (R)

95% C.L. allowed

SNO enhanced neutral current (salt) phase

Single cherenkov ringIsotropic event

Sept. 2003

e + d p + n +

NC: neutral current

n + d 3He + 6.25-MeV

n6 MeV)

Phase-I (Nov. 99 - May 01)

e + d p + n +

n + 35Cl 36Cl + 8.6-MeV ’s

Phase-II (July 01 - Sep 03)

2 ton NaCl dissolved

PRL 92, 181301

Total eff. 39.9%

14.4%(phase-I)

Energy spectra: not assumed but measured

cos sun

Vertex Energy

Isotropy

Not usedto extractreactions

CC / NC = e / active

without assuming 8B spectral shape

CC/NC1.0

0.5

1.0

SNO salt result

No oscillation

Maximal mixing

Maximal mixingexcluded at 5.4

After SNO-salt,LMA-II is excluded at >99%

PRL 92, 181301

LMA-II3

SNO CC/NC disfavors LMA-II, and also maximal-mixing

hep-ph/0309299P.C. Holanda & A.Yu. Smirnov

SNO salt result(CC/NC=0.306)

LMA-II

Maximal mixing

KamLAND: 2nd reactor results with 4.7 data

A. Kozlov (Working Group 1)hep-ex/0406035

All flux free parameter

Verification of standard solar modelJ.N. Bahcall, M.C. Gonzalez-Garcia, C. Pena-Garay, hep-ph/0406294

90, 95,99%, 3

90, 95,99%, 3

All flux BP04

Verification of standard solar modelJ.N. Bahcall, M.C. Gonzalez-Garcia, C. Pena-Garay, hep-ph/0406294

90, 95,99%, 3

95,99%, 3

KamLANDglobal analysis

Oscillation: robust against solar model

• Without KamLAND, and GNO new results:fpp = 1.02 ± 0.02 (1)

fB = 0.88 ± 0.04

fBe = 0.91 + 0.25 / - 0.62

• With KamLAND, and GNO new results:fpp = 1.01 ± 0.02

fB = 0.87 ± 0.04

fBe = 1.03 + 0.24 / - 1.03

flux at productionSolar neutrino measurement

hep-ph/0406294

f “measured” / SSM(BP04)

Small differencedespite KamLANDnew result

Solar-: robust against neutrino oscillation

• 3He proportional counter: to detect n from NC

• Event-by-event separation• Better CC energy spectrum

J.F. Wilkerson, Neutrino 2004

Near future: SNO 3He phase

• All 40 3He strings installed (April, 2004)• Will run for 2.5 years 2 precision of present SNO result

J.F. Wilkerson, Neutrino 2004Near future: SNO 3He phase

• 11,146 PMTs with protection cases

• Full reconstruction from 2005 (plan)

• SK-III from ~2006Acrylic + FRP cases

Near future: full reconstruction of SK

Near future: full reconstruction of SK

M. Nakahata, Neutrino 2004

Toward 7Be solar- observation

C. Galbiati, Neutrino 2004Near future: Borexino

• 210Pb: ~105 reduction needed• R&D almost finished: achieved ~104 reductio

n with test bench• SiO2 adsorption:

achieved 95% reduction• Complex purification sy

stem

Near future: KamLAND-II

Toward 7Be solar- observation

• Solar neutrino oscillation: MSW-LMA is the solution– m2 = 8.2 +0.6

-0.5 10-5 eV2

tan2 = 0.40 +0.09-0.07 (a global analysis by KamLAND)

• Standard solar model verified with 5% accuracy (8B)• Further precise study in the near future (SNO 3He, SK-III, Borexino, KamLAND-II etc) solar astrophysics, search for new phenomen

a

Summary