Takaaki Kajita ICRR, Univ. of Tokyo

Takaaki KajitaICRR, Univ. of Tokyo

Nufact05, Frascati, June 2005

Based on reports at NNN05Next generation of Nucleon decay and Neutrino detectors

http://nnn05.in2p3.fr/

Outline• Introduction• Neutrino oscillation physics with super-beams (This topic should be discussed extensively in th

is workshop. Skip.)• Neutrino oscillation physics with atmospheric ne

utrinos• Neutrino physics with atmospheric neutrinos + s

uper-beams• Solar and supernova neutrinos• A Mton water detector with Gd• Proton decay• R&D• Summary

Apology: references incomplete…

Present: Study of dominant oscillation channels

Future: Study of sub-dominant oscillations

e

3

21

Solar,

KamLAND

Atmospheric

Long baseline

12, m122

Known:Known: Unknown:Unknown:

13

Sign of m2

or

CP ?If 23 ≠/4, is it >/4 or </4 ?

23, |m23

2|

Future Mton class detector

Future long baseline neutrino Future long baseline neutrino experiments - example -experiments - example -

J-PARCJ-PARC

ＢＮＬＢＮＬ

-beam-beam

UNOUNO

MEMPHYS MEMPHYS Hyper-K

Hyper-K

Megawatt class super (or )-beam +

Megaton class water detector

Fermilab NuMI

Hierarchy,

CP, ….

Refs: many talks at NNN05 Many, many talks in this meeting

Neutrino oscillation physics with Neutrino oscillation physics with atmospheric neutrinosatmospheric neutrinos

• Sign of m232

• Is 23 >/4 or </4 ?

• Sign of m232

• Is 23 >/4 or </4 ?TK NNN05

Long neutrino flight length in matter

Very wide L/E solar L/E range is relevant

Long neutrino flight length in matter

Very wide L/E solar L/E range is relevant

Atmospheric neutrino beam :

Sign of Sign of mm22 ? ?

Single-ring e-like Multi-ring e-like

Positive m2

Negative Dm2

null oscillation

cos cos

Relatively high anti-e fraction

More events if m2<0

Relatively high e fraction

More events if m2>0

m2=0.002eV2

s223 = 0.5 s213 = 0.05(0.45 Mtonyr)

If m232 is positive, resonance for neutrinos

If m232 is negative, resonance for anti-neutrinos

E(GeV)

cos

)( eP

22 difference (inverted-normal) difference (inverted-normal)

m2: fixed, 23: free, 13: free 　 Exposure: 1.8Mtonyr

3 3 3

True= normal mass hierarchy assumed.

(A similar but slightly worse sensitivity for inverted mass hierarchy.)

E

Lm

P e

2232

13

2

23

2 27.1sin2sinsin

)(

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).

)( eP

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

)(

)(

oscnoflux

oscflux

e

e

s223=0.4 =0.5 =0.6

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

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.

1.8Mtonyr 1.8Mtonyr

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

Neutrino physics with atmospheric Neutrino physics with atmospheric neutrinos + super beamsneutrinos + super beams

T.Schwetz NNN05, also in this meeting,Huber, Maltoni, Schwetz hep-ph/0501037

Parameter degeneracies in T2K-II Atmospheric neutrinos:

Sensitive to

mass hierarchy and

octant of 23

Combine LBL and atm data to resolve the degeneracies

Resolving the degeneraciesResolving the degeneracies 4MW beam, 2yr neutrino run, 6yr anti-neutrino run, 1Mton detector at 295km

9Mtonyr atmospheric neutrino data

Identifying the mass hierarchyIdentifying the mass hierarchy

s223=0.5 assumed

Atm only

LBL only

1 2 3

LBL+atm

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

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=44% Ptot < 100 MeV/c, BG 0.15ev/Mtyr, eff=17.4%

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

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

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?

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

Remarks on R&DRemarks on R&DPhoto-detector and excavation are the most important items for the co

nstruction of the Mton detector.Photo-detector and excavation are the most important items for the co

nstruction of the Mton detector.

My impression at NNN05◆Excavation of an underground cavity for a Mton class detector seems to be possible, but more site specific R&D are necessary.

◆Photo-detector R&D are going on, but it is still unclear if a much cheaper (and better) photo-detector can be ready by the time of the start of the construction. More R&D are necessary.

◆Also, a more serious discussion on the physics of Mton detector and the detector design might be necessary. One example: what will be the optimal photo-cathode coverage, 10, 20 or 40% ?

◆Excavation of an underground cavity for a Mton class detector seems to be possible, but more site specific R&D are necessary.

◆Photo-detector R&D are going on, but it is still unclear if a much cheaper (and better) photo-detector can be ready by the time of the start of the construction. More R&D are necessary.

◆Also, a more serious discussion on the physics of Mton detector and the detector design might be necessary. One example: what will be the optimal photo-cathode coverage, 10, 20 or 40% ?

It is very good that it was decided to have the NNN workshop every year.

(Aihara, Ferenc, Pouthas, Hamamatsu, Photonics, Electron tubes, NNN05)

(Jung, Nakagawa, Levy, Duffaut, NNN05)

• A Mton water detector will be an excellent neutrino detector for super-beam experiments. (This was not discussed in this talk.)

• A Mton water detector will have a lot of physics opportunities.

• A Mton detector can not be cheap. Therefore it is very nice that it can carry out many important physics.

• Serious detector R&D are necessary.

End

22 difference (normal – inverted) difference (normal – inverted)

m2: fixed, 23: free, 13: free

Exposure: 1.8Mtonyr

3 3 3

True= inverted mass hierarchy assumed.

Effect of the solar term to sub-GeV e-like zeEffect of the solar term to sub-GeV e-like zenith anglenith angle

sub-GeV e-like

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 = 0.6

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

coszenith

N_e

(3

flavo

r) /

N_e

(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.