Takaaki Kajita

ICRR, Univ. of Tokyo

KIAS, Seoul, Nov. 2005

Fig: Senda NP-4

Non-LBL physics with large water Cherenkov detectors

• Atmospheric neutrinos

(300 events /day)• Proton decay• Supernova neutrinos (200,000 events for

SN @galactic center) • Supernova relic neutrinos• Solar neutrinos (300-400 events/day)• ……

Outline• Assumptions

• Neutrino oscillation physics with atmospheric neutrinos

• Proton decay

• Comment on photo cathode coverage

• Summary

Apology: references incomplete…

Assumptions Assumptions

JPARC

Fig: Talk by K.Senda @NP04 (also, hep-ph/0504061)

Off-axis angleDistance from the target (km)

1) Fid. MassKamioka+Korea=0.54 Mton

2) Detector performance = Super-K

1) Fid. MassKamioka+Korea=0.54 Mton

2) Detector performance = Super-K

Neutrino oscillation physics with Neutrino oscillation physics with atmospheric neutrinosatmospheric neutrinos

TK NNN05

e

3

21

Solar,

KamLAND

Solar,

KamLAND

Atmospheric

Long baseline

Atmospheric

Long baseline

12, m122

mass and mixing parameters: 12, 23, 13, , m12

2, m13

2(=m232)

Known:Known: 23, |m232|

KamLAND SNO(+Super-K) Super-K K2K Reactor solar atmospheric long baseline

mass and mixing parameters: 12, 23, 13, , m12

2, m13

2(=m232)

Unknown:Unknown:

13

Sign of m232

or

CP ?

Future long baseline eperiments JPARC-Kamioka-Korea (Atmospheric neutrino exp.s could help….)

Future long baseline eperiments JPARC-Kamioka-Korea (Atmospheric neutrino exp.s could help….)

3

21

e

If 23 ≠/4, is it >/4 or </4 ?

3

or

e

Atmospheric neutrino

experiments

Atmospheric neutrino

experiments

Near future reactor, LBL

exp’s

3

s2212=0.825 m212=8.3×10-5

m223=2.5×10-3

sin213=0

Because of the LMA solution, atmospheric neutrinos should also oscillate by (12, m12

2).

Oscillation probability is different between s223=0.4 and 0.6 discrimination between 23 >/4 and </4 might be possible.

However, due to the cancellation betw

een e and e

, the change i

n the e flux is small.

Peres & Smirnov NPB 680 (2004)

479

Solar term effect to atmospheric Solar term effect to atmospheric

Effect of the solar term to sub-GeV e-like zenith anEffect of the solar term to sub-GeV e-like zenith anglegle

sub-GeV e-like

m212 = 8.3 x 10-5 eV2

m223 = 2.5 x 10-3 eV2

sin2 212 = 0.82sin213=0

sin2 23 = 0.4sin2 23 = 0.5sin2 23 = 0.6

(Pe :100 ~ 1330 MeV) (Pe :100 ~ 400 MeV) (Pe :400 ~ 1330 MeV)

coszenith

e-lik

e (3

fla

vor)

/ e

-like

(2

flavo

r fu

ll-m

ixin

g)

(Much smaller and opposite effect for -like events.)

/e ratio @low energy is useful to discriminate 23

>/4 and </4.

Effect Effect of the of the solar termssolar terms to the to the sub-GeV sub-GeV /e ratio/e ratio (zenith angle dependence)(zenith angle dependence)

sub-GeV P , e < 400 MeV P , e > 400 MeV

m212 = 8.3 x 10-5 eV2

m223 = 2.5 x 10-3 eV2

sin2 212 = 0.82sin213=0

(e

) (3

fla

vor)

(e

) (2

fla

vor

full-

mix

ing)

sin223 = 0.6

sin223 = 0.4sin223 = 0.5

2 flavor (sin2223=.96)

It could be possible to discriminate the octant of 23, if sin223 is significantly away from 0.5.

It could be possible to discriminate the octant of 23, if sin223 is significantly away from 0.5.

Expected oscillation with Expected oscillation with solar terms (2)solar terms (2)

s2212=0.825 m212=8.3×10-5

m223=2.5×10-3

s223=0.4 s213=0.0

Effect of LMA

s223=0.4 s213=0.04cp=/4

Effect of 13

Interference(CP)

)(

)(

oscnoflux

oscflux

e

e

= 1 + P2 (r cos2 23 – 1)P2 = 2 transition probability e in matter driven by m12

2

)(

)(

oscnoflux

oscflux

e

e

In addition, we may have non-zero 13.

E

Lm

P e

2232

13

2

23

2 27.1sin2sinsin

)(

Search for non-zero Search for non-zero 13 13

E

Lm

P e

22

13

2

23

2 27.1sin2sinsin

)(

E

Lm

P e

22

13

2

23

2 27.1sin2sinsin

)(

(m122=0 assumed)

E(GeV)

cos

zeni

th )( eP

Matter effect

s213=0.05 s213=0.00 null oscillation

Electron appearance 1+multi-ring, e-like, 2.5 - 5 GeV

0.45Mtonyr

cos

0.45 Mtonyr

3

Approximate CHOOZ

bound

Binning for this study (= osc. analysis in SK)Binning for this study (= osc. analysis in SK)

E

Single-Ring

Multi-Ring

Up-stop

Up-through

37 momentum bins x 10 zenith bins = 370 bins in total37 momentum bins x 10 zenith bins = 370 bins in total

Multi-Ring e

Single-Ring e

PC-stop

PC-through

10 zenith angle bins for each box.

10 zenith angle bins for each box.

Small number of events per binSmall number of events per bin

Poisson statistics to claculate 2 with 45 systematic error termsPoisson statistics to claculate 2 with 45 systematic error terms

Multi-GeV

Sub-GeV

CC e CC

For more details: please ask H.K.Seo and S.Nakayama

0.092 Mtonyr Super-K data0.092 Mtonyr Super-K data

Analysis with and w/o solar

terms

with 12 terns(best fit s223

= 0.51)

w/o 12

3

2

1

sin223

sin2

13

Search for non-zero 13

E(GeV)

cos

zeni

t

h

)( eP

Discrimination between Discrimination between 23 23 >>/4 and </4 and </4 /4 with the (12) and (13) termswith the (12) and (13) terms s223=0.40 ~ 0.60

s213=0.00~0.04 cp=45o

Discrimination between 23>/4 and </4 is possible for all 13.

Discrimination between 23>/4 and </4 is possible for all 13.

1.8Mtonyr (or 3.3yr×0.54Mton)

1.8Mtonyr (or 3.3yr×0.54Mton)

Discrimination between 23>/4 and </4 is marginally possible only for s213 >0.04.

Discrimination between 23>/4 and </4 is marginally possible only for s213 >0.04.

sin223 sin223

sin2

13

sin2223=0.96 sin2223=0.99

90%CL 90%CL

Test point

Fit result

M.Shiozawa et al, RCCN Int. Workshop on sub-dom. Atm. Osc. 2004

Improvement Improvement possible ?possible ?

m212 = 8.3 x 10-5 eV2

m223 = 2.5 x 10-3 eV2

sin2 212 = 0.82sin213=0

P , e < 400 MeV

sin223 = 0.6

sin223 = 0.4sin223 = 0.5

2 flavor (sin2223=.96)

(e

) (3

fla

vor)

(e

) (2

fla

vor

full-

mix

ing)

tru

e

0.8 Mtonyr = SK 20yr = HK 0.8yr0.8 Mtonyr = SK 20yr = HK 0.8yr

S.Nakayama, RCCN Int. Workshop on sub-dom. Atm. Osc. 2004

Search for proton decay Search for proton decay

Lifetime in benchmark scenarios

J.Ellis NNN05 C.K.Jung NNN05

How long is the predicted proton lifetime ?

SK limit (e0)

SK limit (K+)

Search for pSearch for pee++00

Ptot < 250 MeV/c, BG 2.2ev/Mtyr, eff=40% Ptot < 100 MeV/c, BG 0.15ev/Mtyr, eff=17%

Atm 20Mtonyr

free proton decay

bound proton decay

Main target is free proton decays for the tight cut.

pe0 Monte Carlope0 Monte Carlo

e+e+

00

M.Shiozawa NNN05

Now (near future)Future

Lifetime sensitivity for pLifetime sensitivity for pee++00

Normal cut, 90%CL 3 CLTight cut, 90%CL 3 CL

pe+0 sensitivity

5Mtonyrs ~1035 years@90%CL~4x1034 years@3CL

5Mtonyrs5Mtonyrs

ppKK++ (1) 16OOK+15N , , KK++→→

e+236MeV/c6 – 10 Me

V

Signal region

Background = 0.7= 8.6%Candidate = 0

NPMT-hit distribution for the prompt gamma search

(Also, searches for

(2) pK+ (K++0)

(3) PK+(K++, without ) )

νKνK++ sensitivity (based on SK criteria) sensitivity (based on SK criteria)

τ/B > 2 × 1034yr (5Mtonyr, 90%CL)

Question: How much photo cathode coverage is necessary?Question: How much photo cathode coverage is necessary?

Most updated number = 2,3×1033 yrs

Most updated number = 2,3×1033 yrs

5Mtonyrs5Mtonyrs

e

cMeV

MeVN

NKO

)/236(

)6(15

*1516

12nsec

2.2sec

Photo cathode coverage ?Photo cathode coverage ?• Cost for the photo-detectors is a significant part of the total detector cost.

• If 40% coverage with 50cm diameter PMT’s for 0.27 Mton fiducial mass; 100,000 PMT’s. If 100 (200?) $ / PMT 100M$ (200?M$)

• Important to understand minimum requirement of photo-coverage from each physics topics

• SK-II (19% coverage SK-I 40%) is a good opportunity to investigate physics sensitivity with reduced photo- coverage. LBL physics

Atmospheric neutrinos 　　　 Proton decay (e0) This talk Proton decay (K+) 　 Astrophysical neutrinos (SN, solar neutrinos? ...)

Proton mass vs. momentumProton mass vs. momentum

SK-I=40.1%

SK-I8 /2.2Mtyr

SK-II2 /0.45Mtyr

SK-II=41.1%

atm(BG) MC pe0 MC

Proton mass and momentumProton mass and momentum

SK-I SK-I

SK-IISK-II

pe0 MC

p mom. resolution; 177MeV(68%)171 ( free proton) 81MeV(68%)83

p mom. resolution; 177MeV(68%)171 ( free proton) 81MeV(68%)83

p mass resolution; 33.8MeV42.3 (free proton) 28.5MeV35.2

p mass resolution; 33.8MeV42.3 (free proton) 28.5MeV35.2

pe0 looks OK with 20% photo cathode coverage. pe0 looks OK with 20% photo cathode coverage.

Photo cathode coverage ?Photo cathode coverage ?

LBL physics Need careful checks

Atmospheric neutrinos 20% probably OK. (No proof today…)

Proton decay (e0) 20% looks OK.

Proton decay (K+) We will know in a month or half a year… 　 Astrophysical neutrinos (SN, solar ? ...) Need checks…

• Mton class water detectors will have a lot of physics opportunities.

• Mton class detectors can not be cheap. Therefore it is very nice that it could carry out many important physics.

End

Solar neutrino physics with Mton detectors Solar neutrino physics with Mton detectors

Solar global

KamLAND

Solar+KamLAND

95%

99.73%P( e

e)

Vacuum osc. dominant

matter osc.

(MeV)

Do we want further evidence for matter effect ?

M.Nakahata NNN05

Day-night asymmetry

Expected signalExpected signal8B spectrum distortion

Enough statistics to see distortion.

Energy scale calibration should be better than ~0.3%.

Ee (MeV)

Dat

a/S

SM

5 Mton·years

Correlated sys. error of SK

sin2=0.28,

m2 =8.3×10-5 eV2

1/2 of SK

Day-night stat. significance

3 signal can be obtained with 0.5% day-night systematic error.

In both cases, systematic errors or background are assumed to be better than SK.

Supernova events in a Mega-ton detectorSupernova events in a Mega-ton detectorA.Dighe NNN05

Number of anti-e+p interactions = 200,000 - 300,000 for a galactic Supernova (@10kpc)

◆Initial spectra rather poorly known.

◆Only anti-e observed

Difficult find a “clean” observable, which is (almost) independent of the assumptions on the initial spectra.

◆Initial spectra rather poorly known.

◆Only anti-e observed

Difficult find a “clean” observable, which is (almost) independent of the assumptions on the initial spectra.

Supernova shock and neutrino oscillationsSupernova shock and neutrino oscillationsAssume: nature = inverted hierarchy

Assume: nature = inverted hierarchy

Anti-eAnti-e

If sudden change in the average energy is observed Inverted mass hierarchy and sin213>10-5.

If sudden change in the average energy is observed Inverted mass hierarchy and sin213>10-5.

sin213

Forward shock

Reverse shock

m132 resonance

m122 resonance

A.Dighe NNN05R.Tomas et al., astro-ph/0407132

Mton is large: Mton is large: TThe detectors can see extragalactic SNehe detectors can see extragalactic SNe

Nearby SN rate

SK

HK

Detection probability

S.Ando NNN05

Supernova relic neutrinos (SRN)Supernova relic neutrinos (SRN)

SRN prediction

SK result

e+anti-e

Invisible e

SNR limit90%CL

90%CL limit: 1.2 /cm2/sec (E>19MeV)(which is just above the most recent prediction 1.1/cm2/sec)

get information on galaxy evolution and cosmic star formation rate get information on galaxy evolution and cosmic star formation rate

With a Mton detector, it must be possible to see SRN signal With a Mton detector, it must be possible to see SRN signal

S.Ando,M.Nakahata NNN05

Mton detector with Gd loaded waterMton detector with Gd loaded waterGADZOOKS! M.Vagins NNN05

B.G. reduction by neutron tagging

No neutron tagging

Statistically 4.6excess (Evis > 15 MeV)

Simulation: M.Nakahta NNN05

)8('

MeVEsGdGdn

nepe

(0.2% GdCl3)

M.Vagins, J.Beacom hep-ph/0309300

Invisible e

End

45 systematic 45 systematic error terms error terms

(0, Free parameter) Flux, Nu-int, Fit; absolute normalization(1) Flux; (nu_mu + anti-nu_mu) / (nu_e + anti-nu_e) ratio ( E_nu < 5GeV )(2) Flux; (nu_mu + anti-nu_mu) / (nu_e + anti-nu_e) ratio ( E_nu > 5GeV )(3) Flux; anti-nu_e / nu_e ratio ( E_nu < 10GeV )(4) Flux; anti-nu_e / nu_e ratio ( E_nu > 10GeV )(5) Flux; anti-nu_mu / nu_mu ratio ( E_nu < 10GeV )(6) Flux; anti-nu_mu / nu_mu ratio ( E_nu > 10GeV )(7) Flux; up/down ratio(8) Flux; horizontal/vertical ratio(9) Flux; K/pi ratio(10) flight length of neutrinos(11) spectral index of primary cosmic ray above 100GeV(12) sample-by-sample relative normalization ( FC Multi-GeV )(13) sample-by-sample relative normalization ( PC + Up-stop mu )(14) MA in QE and single-(15) QE models (Fermi-gas vs. Oset's)(16) QE cross-section (17) Single-meson cross-section (18) DIS models (GRV vs. Bodek's model)(19) DIS cross-section (20) Coherent- cross-section (21) NC/CC ratio(22) nuclear effect in 16O(23) pion spectrum(24) CC cross-section

(25) Reduction for FC(26) Reduction for PC(27) Reduction for upward-going muon(28) FC/PC separation(29) Hadron simulation (contamination of NC in 1-ring -like)(30) Non- BG ( flasher for e-like )(31) Non- BG ( cosmic ray muon for mu-like )(32) Upward stopping/through-going mu separation(33) Ring separation(34) Particle identification for 1-ring samples(35) Particle identification for multi-ring samples(36) Energy calibration (37) Energy cut for upward stopping muon(38) Up/down symmetry of energy calibration (39) BG subtraction of up through (40) BG subtraction of up stop (41) Non-e contamination for multi-GeV 1-ring electron (42) Non-e contamination for multi-GeV multi-ring electron (43) Normalization of multi-GeV multi-ring electron(44) PC stop/through separation

Flux (13)Flux (13)

interaction (11) interaction (11)

Detector, reduction and reconstruction (20)Detector, reduction and reconstruction (20)

sub-GeV -like zenith angle

sub-GeV -like

(P : 200 ~ 1330 MeV)

m212 = 8.3 x 10-5 eV2

m223 = 2.5 x 10-3 eV2

sin2 212 = 0.82

sin2 23 = 0.4sin2 23 = 0.5sin2 23 = 0.62 flavor (sin2 223 = 0.96)

X : zenith angleY : N_ (3 flavor) / N_ (2 flavor full-mixing)

(P : 200 ~ 400 MeV) (P : 400 ~ 1330 MeV)

Discrimination between Discrimination between 23 23 >>/4 and </4 and </4 /4 with the (12) and (13) termswith the (12) and (13) terms s223=0.40 ~ 0.60

s213=0.00~0.04 cp=45o

Discrimination between 23>/4 and </4 is possible for all 13.

Discrimination between 23>/4 and </4 is possible for all 13.

1.8Mtonyr = SK 80 yrs = 3.3 HK yrs1.8Mtonyr = SK 80 yrs = 3.3 HK yrs

Discrimination between 23>/4 and </4 is marginally possible only for 13 >0.04.

Discrimination between 23>/4 and </4 is marginally possible only for 13 >0.04.

sin223 sin223

sin2

13

sin2223=0.96 sin2223=0.99

90%CL 90%CL

Test point

Fit result