Country Report - Japan April 2014 Capt. Takaaki MURASE Japan Federation of Pilots’ Associations.
Takaaki Kajita ICRR, Univ. of Tokyo
description
Transcript of 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.