future accelerator based neutrino experiments takashi kobayashi institute of particle and nuclear...
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Future Accelerator Based Neutrino Experiments
Takashi KobayashiInstitute of Particle and Nuclear Studies,
High Energy Accelerator Research Organization (KEK)
Aug.22,2011Lomonosov ConfMoscow
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Standard picture of 3 flavor mixing
3
2
1
PMNSU
e
100
0
0
0
010
0
0
0
001
U 1212
1212
1313
1313
2323
2323MNS cs
sc
ces
esc
cs
sci
i
)sin(s ),cos(c ijijijij
2
ne
nm
nt
Flavor eigenstates m1
m2
m3
Mass eigenstates
6 independent parameters govern oscillationq12, q23, q13, dDm12
2, Dm232, Dm13
2
Atm/Acc Acc/Reactor Sol/Reactor
2
Dmij=mi2-mj
2
Pontecorvo-Maki-Nakagawa-Sakata Matrix (CKM matrix in lepton sector)
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Present knowledge (before June, 2011)
3
OR
n1
n2
n3
Which??
ne??
Big diff from KM matrix
d unkown
Sol/Reactor
Atm/Acc
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Indications of large q13
4
T2K6event obs.1.5 BG exp’ed2.5s(June 13,2011)
MINOS62event obs.49.5 BG exp’ed1.7s(June 24,2011)
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New results on nm disappearance T2K released the first
disappearance result Consistent with MINOS &
SK results MINOS data indicates slight
tension between nm and anti-nm
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What’s next? Immediate issues with on-going experiments
EXPERIMENTALLY establish non-zero q13 as soon as possible
Precise measurement of q23, Dm23 (both for nm and anti-nm), whether maximal mixing or not?
Next most important goal: CPV CP is violated/conserved in neutrino? What is the mechanism of violation? PMNS-type
“standard” scenario or anything exotic origin?
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Toward one of big goals of particle physics: Origin of Matter-dominated Unvierse
Sakhalov’s 3 conditions
Baryon number violationProton decay
CP violationQuark CPV seems not sufficientLepton CPV may contribute
Non-equilibulium7
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88
nmne appearance and CPV
132312sin sss CPV effect
(sinq12~0.5, sinq23~0.7, sinq13<0.2)
Unknown!
CPVSol term
The size of q13 decide future dir.!
ne appearance is golden mode for CPV IF ne appearance exist No CPV effect in disappearance Only nm beam is presently technically available Small leading CPC term Large CPV effect (⇔nt app.)
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Expected CPV (&matter) effects (w/ “standard” PMNS framework)
~20% CPV effect at sin22q13=0.1 w/ sindCP=1 (max. vio.) at 1st peak To detect CPV >3s for sind>0.2 (Asym=4%) O(10k) events necessary Much higher statistics is necessary >MW proton & huge detector mandatory
CPV asymmetry get smaller for larger q13
Severer requirement on systematic error Matter effect becomes comparable (@295km) or dominant (2300km) at 1st peak ( potential to
determine mass hierarchy ) CPV asymmetry get much larger for 2nd peak
Matter effect become small correction9
T2K 90% region
T2K 90% region
T2K 90% region
1st peak @ 2300km (4.65GeV)1st peak @ 295km (0.6GeV) 2nd peak @ 2300km (1.6GeV)
Pure CPV effect
Pure matter effect
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Essential requirements for CPV discovery
Order of magnitude higher statistics from present generation experiments
High intensity beam (Multi-MW)
Increase statistics High sensitivity huge detector
Increase statistics Increase signal efficiency Reduce background Reduce systematic errors Should also capable for proton decay detection
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How to measure CPV & sign(Dm23)
νe appearance energy spectrum shape Peak position and height for 1st, 2nd maximum and minimum Measure both sind & cosd terms can discriminate 0deg vs 180deg
Difference between νe and νe behavior Sensitive to any mechanism to make asymmetry (No assumption) Basically measure sin d term
Distance: Larger L Matter effect large Sensitive to sign(Dm23) too Smaller L (lower E): Purer CPV measurement 11
665km 2300km
CPVMatter
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Future MW proton facilities in the world
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Staged approach
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“Available” technologies for huge detector
Liq Ar TPC Aim O(100kton) Electronic “bubble chamber”
Can track every charged particle Down to very low energy
Neutrino energy reconstruction by eg. total energy No need to assume process type Capable upto high energy
Good PID w/ dE/dx, pi0 rejection Realized O(1kton)
Water Cherenkov Aim O(1000kton) Energy reconstruction
assuming Ccqe Effective < 1GeV
Good PID (m/e) at low energy Cherenkov threshold Realized 50kton
13
Good at Wideband beam
Good at low E (<1GeV) narrow band beam
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Possible experimental configuration Multi-MW beam + Longer distance O(1000km)+ Wide
band beam + LiqAr Energy spectrum measurement Cover both 1st and 2nd peaks Possible to determine “everything” in 1 shot
CPV Hierarchy q23 octant
Multi-MW beam + Shorter distance (a few 100km) + Low energy narrow band beam + Water Cherenkov Nue/nuebar asymtery of 1st peak Possible to determine
CPV Need external input to discriminate mass hierarchy (such as atm
nu)14
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Planned future CPV experiments
Experimental configuration
Liq. Ar TPC WC Comment
• MW beam• O(1000km)
baseline• WBB• Spectrum
measurement
• J-PARC-Okinoshima (100kt@658km)
• CERN-Pyhasalmi (LAGUNA, 100kt@2300km)
• US-LBNE/LAr (34kt@1300km)
• US-LBNE/WC (200kt@1300km)
• Sensitive to matter effect = mass hierarchy
• Could possibly detect deviation from “standard” PMNS spectrum shape
• MW beam• a few 100km
baseline• Sub-GeV NBB• n/anti-n
asymmetry
• J-PARC-HyperK (540kt@295km)
• CERN-Frejus (LAGUNA, 440kt@130km)
• Less dependence on assumption
• Need other input for mass hierarchy
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P32 proposal (Lar TPC R&D)Recommended by J-PARC PAC(Jan 2010), arXiv:0804.2111
Kamioka L=295km OA=2.5deg
Okinoshima L=658km OA=0.78deg Almost On-Axis
Scenarios in Japan
J-PARC
1.7MW??MW
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J-PARC-HyperK @ Kamioka
3s
sin2q23=0.6 sin2q23=0.5 sin2q23=0.4
mass hierarchy
determination w/
atmospheric n
leptonic CPV w/ JPARC n
10 yrs exposure of atm. n data.Super-K syst. errors are assumed.5 yrs of 1.66 MW JPARC n data.
5% syst. errors are assumed.
• Very good chance to detect CPV & have potential on sign(Dm23) with atm n
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Hyper-K Base-Design• 1Mton total volume, twin cavity• 0.54Mton fiducial volume• Inner (D43m x L250m) x 2• Outer Detector >2m• Photo coverage 20% (1/2 x SK)
20” PMT w/ cover
FEM analysis(Factor of safety)
• Base-design to be optimized
• Geological survey of the site is going on
• Qualitative studies on physics potential
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J-PARC to Okinoshima
P32 proposal (Lar TPC R&D)Recommended by J-PARC PAC(Jan 2010), arXiv:0804.2111
Scenario 1
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J-PARC to Okinoshima
P32 proposal (Lar TPC R&D)Recommended by J-PARC PAC(Jan 2010), arXiv:0804.2111
Scenario 1
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Physics potential
Beam νe
Background
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• Very good chance both to detect CPV & determine sign(Dm23)
CPV Hierarchy
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European Activities: LAGUNA-LBNO
~500kt Water Cherenkov
100kt Liq Ar. TPC
GLACIER
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LAGUNA-Pyhasalmi sensitivity
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CPV
Mass hierarchy unknown assumption
A.Rubbia EPS-HEP 2011
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R&D toward realizing 100kt LArTPC
24Site visit
Double phase readout test @ ETHZ (CERN RE18)
J-PARC T32 exp(ETHZ/KEK/Iwate/Waseda)
250L LAr TPC
180k trig (80k Kaon)
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LBNE in US
25B.Svoboda, GLA2011
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US-LBNE sensitivities
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T2K regionT2K region
T2K region T2K region
L.Whitehead, B.Rebel @ NNN2010
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Implication of large q13 on Future If sin22q13> ~0.01
Conventional Multi-MW super beam long baseline experiment will be really promising to explore CPV in lepton sector
We need to put even more effort to formulate the future project in this direction as soon as possible
IF not Need “ideal” beam such as Neutrino Factory or beta beam to probe CPV
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T2K region
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Summary Indication of large q13 makes conventional beam long baseline experiment be
promising to probe CPV and sign(Dm232)
To realize the next generation experiment, Multi-MW beam power & High sensitivity huge detector MUST BE REALIZED
Two detector options are under consideration: O(500kt) Water Cherenkov & 100kton LiqAr TPC
Two promising experimental configurations WBB w/ LiqAr TPC Spectrum measurement for 1st & 2nd peak NBB w/ WC n/anti-n asymmetry
Design study & R&D for future CPV search are intensively being done around the world J-PARC Kamioka (WC)/Okinoshima(LAr) CERN Frejus(WC)/Pihasalmi(LAr) (LAGUNA-LBNO) FNAL DUSEL (WC/LAr) (LBNE)
It is desirable to realize both configurations in the world, but it may not be so easy Need to be very careful on physics potential
Personally, I am interested in how to know origin of CPV, whether PMNS or something exotic International cooperation & coordination needed
EU/Russia/Japan(KEK) are working coherently under LAGUNA consortium
Need to be ready to “go” when finite q13 is concluded28