superbeam long baseline experiments
DESCRIPTION
100830 Neutrino Summer School @Tokai. Superbeam long baseline experiments. Takashi Kobayashi KEK. n e. n m. n t. 3 flavor mixing of neutrino. Flavor eigenstates. Mass eigenstates. m 1. Unitary matrix. m 2. m 3. 6 parameters q 12 , q 23 , q 13 , d - PowerPoint PPT PresentationTRANSCRIPT
Superbeam long baseline experiments
Takashi KobayashiKEK
100830Neutrino Summer School@Tokai
2
3
2
1
MNSU
e
10000
0010
0
00
001U 1212
1212
1313
1313
2323
2323MNS cssc
ces
esc
cssc
i
i
e
Flavor eigenstates m1
m2
m3
Mass eigenstates
6 parametersq12, q23, q13, Dm12
2, Dm232, Dm13
2)sin(s ),cos(c ijijijij qq
3 flavor mixing of neutrino
Unitary matrix
2
Dmij=mi2-mj
2
T.Kobayashi (KEK) 3
Known and Unknowns
OR
Solar & Reactor• q12~33o
• Dm122~0.00008eV2
Atomspheric + Acc• q23~45o • Dm23
2~0.0025eV2
Unknown!• q13<10o
• (Dm132~Dm23
2)?• ???
1
2
3
Mass hierarchy
e??
4
Unknown properties of neutrino
4
q13? Last unknown mixing angle T2K, NOvA, Double Chooz, RENO, DayaBay
CP invariance ? Mass hierarchy ?
Absolute mass Tritium beta decay, double-beta
Majorana or Dirac? Double-beta
Next generation accelerator based expriemtns
Toward unraveling the mystery of matter
dominated universe
5
Sakharov’s 3 conditions
To generate Baryon asymmetry in the unverse There is a fundamental process that violates
Baryon number C and CP invariance is violated at the same
time There is a deviation from thermal
equilibrium acting on B violating process
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Toward origin of matter dominated universe
Quark sector CPV is found to be not sufficient for reproducing present baryon content
Scenario for baryogenesis through lepton CP violation: Leptogenesis CPV in lepton sector is responsible for B genesis
CPV in neutrino oscillation could provide a key to unravel mystery of origin of matter
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Let’s find CPV in lepton sector I give you
1000 億円 or 1.2 Billion USD 755M GBP 55 Billion INR 1,401 Billion Won 2,130 Billion Peso 7.9 Billion 元 918 Million Euro 35 Billion Ruble 1.2 Billion CHF
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Let’s design an experiment to search for CPV in lepton sector
If you find any good idea, let’s write a paper!
One condition: Within 10years
How? …. : Q1 Do we really need oscillation phenomena to
probe CPV?? Can’t we attack CPV in an experiment which
fit in an experimental hall like such as Kaon CPV or B CPV
Why??
9
Measuring CPV in quark sector
Through loop diagram Amplitude (m∝ u,c,t/MW)2
Please calculate Since quark is heavy (especially top), this
process becomes measureable10
W W
s,b
d
u,c,t
u,c,ts,b
W
u,c,t
VCKM VCKM
VCKMVCKM VCKMVCKM
How about lepton sector?
Amplitude (m∝ /MW)2
Standard model process STRONGLY suppressed Thus, good field to search for physics beyond
standard model
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W
e,,VMNS
VMNSe
gExample: eg
Oscillation
12
l l’
1
2
3
i
liitiE
liet
i
liimtiE
lmiet
MNSliU
Oscillation (cont)
13
i
liimtiE
lmiet
If Ei are same for all mass eigenstates E
mliEt
lmiEt
iliim
iEtlm
ee
et
Ei’s are same, no oscillation, in other word, Ei’s are different, we can probe mixing matrix through oscillation
Difference of Ei, ie, phase advance difference is essential
jiljmjlimi
tEEilmml UUUUetP ji
,
**2
)100()1(~ 2/)( 2
kmOLOee ELmitEEi ijji D
222jiij mmm D For Dm2~10-3eV2
14B.Kyser, in this SS
Q2: What oscillation process is best?
OK, now, we somehow understand we need (long baseline) oscillation phenomena to probe matrix elements and attack CPV.
What type of oscillation is best? Fundamental physics reason Experimental feasibility
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Disappearance ? Appearance?
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i
liimtiE
lmiet
ili
tiE
iliil
tiEll
Ue
et
i
i
2
Oscillation probability
Disappearance case
There is no place for complex phase in UMNS to appear
Disappearance has no sensitivity on (standard) CPV
Appearance Conventional beam (~GeV)
e Not yet discovered
Dominant oscillation mode
Neutrino factory/Beta beam (~10GeV) e e
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Next talks
e vs appearance
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Oscillation probability (w/ CPV)
sin2 AAP
Relative effect of CPV
AAACPCCPV sinsin/ 2
CP conserved part
CPV part
case, probability A sin∝ 22q23, is known to be large, relative effect of CPV
becomes small Also experimentally, identification of nt (out of lots of nm interactions ) is
not easy
For nue appearance, A sin∝ 22q13 is known to be small Large CPV effect expected
Matter effect
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e
Z
e
X X
e
W
e-
e- e
Z
X X
Z
X XNC
Interactions through propagation in matter
CC
Matter effect
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e
tot
e
Hdtdi
00000000
1
3
2
1 W
MNSMNStot
VU
EE
EUH
Relative size of effect E∝ Change sign when Dm2 sign
change: Can probe sign Change sign when ⇔bar:
Fake CPV effect
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Oscillation probabilities
qq ELmP e /27.1sin2sinsin 213
213
223
2 D
qq ELmP x /27.1sin2sincos1 223
223
213
4 D
q ELmP xe /27.1sin2sin1 213
213
2 D
contribution from Dm12 is small
e appearance (LBL/Atm)
disappearance (LBL/Atm)
e disappearance (Reactor)
D
DDD
223
213
223
212
mL
Emmm
when
12
3
Dm232
(No CPV & matter eff. approx.)
~1
~0.5
≪1
Pure q13 and Dm132
q13 and Dm132
q23 and Dm232
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e appearance & CPV
, a-a for e
]GeV[]cmg[][eV1056.7 3
25 Ea Matter eff.:
CP-odd
qq sin
sin2sin
13
12212
D
ELm
PPPPACP
Solar
Main
Matter
# of signal sin∝ 2q13 (Stat err sin∝ q13),CP-odd term sin∝ q13
Sensitivity indep. from q13
(if no BG & no syst. err)
23Takashi Kobayashi (KEK), PAC07
23
All mixing angle need to be non-zero
, a-a for e
]GeV[]cmg[][eV1056.7 3
25 Ea Matter eff.:
CP-odd
Leading
132312sin sss CPV effect
(where sinq12~0.5, sinq23~0.7, sinq13<0.2)
+ other terms..
Same as Kobayashi-Maskawa model which require 3x3 to incorporate CPV
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CPV vs matter effect
295km 730km
)( ePP )( ePP
Smaller distance/lower energy small matter effectPure CPV & Less sensitivity on sign of Dm2
Combination of diff. E&L help to solve.
e osc. probability w/ CPV/matter
@sin22q13=0.01
Lepton Sector CP Violation
Effect of CP Phase δ appear as– νe Appearance Energy Spectrum Shape *Peak position and height for 1st, 2nd maximum and minimum *Sensitive to all the non-vanishing δ including 180° *Could investigate CP phase with ν run only
– Difference between νe and νe Behavior
3
2
1
231323122313122312231312
231323131223122313122312
1312131312
ccsccssesscscescssseccsscecssesccc
ii
ii
ie
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How to do experiment?
OK, we now understand Importance of CPV in lepton sector Necessity of oscillation to probe CPV What process is suited for CPV measurement Behavior of oscillation probabilities and
relevant physicsSo, now, let’s consider more on experimentation!
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Super Beam
Conventional neutrino beam with (Multi-)MW proton beam (Fact)
Pure beam ( 99%)≳ e ( 1%) from ≲ pe chain and K decay(Ke3) / can be switched by flipping polarity of focusing
device
ProtonBeam
Target FocusingDevices
Decay Pipe
Beam Dump
p,K
Strongly motivated by high precision LBL osc. exp.
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High intensity narrow band beam-- Off-axis (OA) beam --
(ref.: BNL-E889 Proposal)
qTargetHornsDecay Pipe
Far Det.
Decay Kinematics
Increase statistics @ osc. max.Decrease background from HE tail
1/gp~q Ep(GeV)
E(GeV)
E(G
eV)
5
12
]mrad[30]GeV[max
q E
flux
/ flux for CPV meas.
-15%@peak
1021POT/yr
Sign flip byjust changinghorn plarity
Example
50GeV protonAt 295km
Cross sections Cross section E∝
Higher energy higher statistics
Anti-neutrino cross section smaller than neutrino by ~1/3 Why? Take ~3 times more
time for anti-neutrino measurements to acquire same statistics as neutrino
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ep0
Back ground for e appearance search• Intrinsic e component in initial beam
• Merged p0 ring from interactions
e appearance search
“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 (/e) at low energy Cherenkov threshold Realized 50kton 32
Good at Wideband beam
Good at low E (<1GeV) narrow band beam
Neutrino Energy E reconstruction in Water Cherenkov
CC quasi elastic reaction
q
cospEm2mEm
EN
2N
+ n → + p
-
p
(E, p)q
QE
inelastic
0
0 .5
1
1 .5
2
2 .5
3
3 .5
4
4 .5
0 1 2 3 4 5E (G e V )
c
ross
sec
tions
(10
cm)
-38
2
In e la s t ic
C C q e
+ n → + p + p
-
p
(E, p)ql
p
2 approaches for CPV (and sign(Dm2) ) Energy spectrum measurement of appeared e
Only w/ numu beam (at least early part) Measure term cos∝ (and sin)
Assume standard source of CPV ( in MNS) Cover 2nd oscillation maximum (higher sensitivity on CPV)
Higher energy = longer baseline favorable Wideband beam suited Liq Ar TPC is better suited
Difference between P(numunue) and P(numubar nuebar) Measure term sin∝ Not rely on the standard scenario
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Angle and Baseline
OA3°
OA0°OA2°
OA2.5°
fl
ux• Off-axis angle– On-Axis: Wide Energy Coverage, ○Energy Spectrum Measurement ×Control of π0 Background– Off-Axis: Narrow Energy Coverage, ○Control of π0 Background ×Energy Spectrum Measurement → Counting Experiment
• Baseline– Long: ○ 2nd Osc. Max. at Measurable Energy × Less Statistics ? Large Matter Effect– Short: ○ High Statistics × 2nd Osc.Max.Too Low Energy to Measure ? Less Matter Effect
(E/L)
CP=90CP=270
CP=0
Dm312 = 2.5x10-3 eV2
sin22q13 = 0.1No matter effects
νμ νe oscillation probability
Osc
illat
ion
prob
abili
ty
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“Available” beams
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FNAL possible future Plan
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CERN future possibilities
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Present accelerator complex Various POSSIBLE scenarios
Under discussion
CERN possibilities
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Okinoshima
658km0.8deg. Off-axis
KamiokaKorea
1000km1deg. Off-axis
295km2.5deg. Off-axis
Possible scenarios in Japan
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Okinoshima
658km0.8deg. Off-axis
•Cover 1st and 2nd Maximum•Neutrino Run Only 5Years×1.66MW•100kt Liq. Ar TPC
-Good Energy Resolution-Good e/π 0 discrimination
•Keeping Reasonable Statistics
Scenario 1 δ=0°
νeSpectrum
Beam νe
Background
CP Measurement Potential
NP08, arXiv:0804.2111
δ=90°
δ=180° δ=270°
sin22θ13=0.03,Normal Hierarchy
3s
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295km2.5deg. Off-axis<E>~0.6GeV
TokaiKamioka
•Cover 1st Maximum Only•2.2Years Neutrino+7.8Years anti-Neutrino Run 1.66MW•540kt Water Cherenkov Detector
Scenario 2
K.Kaneyuki @NP08
=0 =p/2
Er
ec
Er
ecEr
ec
Er
ec
+ BG+ee BG
signal+BG
sin22θ13=0.03,Normal Hierarchy
sin2 2q 1
3Fr
actio
n of
3s
3s
CP sensitivity
sin22θ13
deg.
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Site studies in Europe
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US Superbeam Strategy: Young-Kee Kim, Oct. 1-3, 2009
NSF’s proposedUnderground Lab.
DUSEL
1300 km
Project X: ~2 MW
700kW15kt Liquid Scintillator
Under construction
NOvA
~50 kton Liquid Ar TPC~300 kton
Water Cerenkov
MiniBooNESciBooNE
MINOSNOvA
MINERvAMicroBooNE
735 km2.5 msec810 km
Combination of WC and LAr
FNAL possibilities
FNAL-DUSEL potential
To realize the experiments
Need Finite (reasonable) q13 T2K, NOvA,
Reactors! High power (>MW) neutrino beam Huge high-sensitivity detector YOUR CHALLENGE OR YOUR NEW IDEA!
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Summary Properties of neutrino are gradually being revealed However still yet far unknown than quarks
CPV, mass hierarchy, etc. Especially, CP symmetry could be a critical key to answer
the fundamental question: What is the origin of matter in the universe
Future superbeam long baseline oscillation experiments have chance to discover CPV effect (if q13 is large enough to be detected in present on-going experiments)
Already many studies and developments (beam, detectors) are being made around the world to realize the experiments
Lot’s of challenges and funs forseen Let’s enjoy!
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