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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

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superbeam long baseline experiments

100830

Neutrino Summer School

@Tokai

Superbeam long baseline experiments

Takashi Kobayashi

KEK

3 flavor mixing of neutrino

ne

nm

nt

3 flavor mixing of neutrino

Flavor eigenstates

Mass eigenstates

m1

Unitary matrix

m2

m3

6 parameters

q12, q23, q13, d

Dm122, Dm232, Dm132

Dmij=mi2-mj2

2

known and unknowns
Known and Unknowns
  • Solar & Reactor
    • q12~33o
    • Dm122~0.00008eV2
  • Atomspheric + Acc
    • q23~45o
    • Dm232~0.0025eV2
  • Unknown!
    • q13<10o
    • (Dm132~Dm232)?
    • d ???

ne??

n3

n2

OR

n1

Mass hierarchy

unknown properties of neutrino
Unknown properties of neutrino

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

4

sakharov s 3 conditions
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
toward origin of matter dominated universe
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
let s find cpv in lepton sector
Let’s find CPV in lepton sector

Let’s design an experiment to search for 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

If you find any good idea, let’s write a paper!

One condition: Within 10years

how q1
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??
measur ing cpv in quark sector
Measuring CPV in quark sector
  • Through loop diagram
  • Amplitude ∝ (mu,c,t/MW)2
    • Please calculate
  • Since quark is heavy (especially top), this process becomes measureable

VCKM

u,c,t

VCKM

s,b

W

W

W

u,c,t

d

s,b

VCKM

VCKM

VCKM

u,c,t

VCKM

how about lepton sector
How about lepton sector?

g

Example: meg

  • Amplitude ∝ (mn/MW)2
  • Standard model process STRONGLY suppressed
    • Thus, good field to search for physics beyond standard model

W

ne,nm,nt

m

e

VMNS

VMNS

oscillation
Oscillation

n1

nl

n2

nl’

n3

oscillation cont
Oscillation (cont)

If Ei are same for all mass eigenstates E

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

For Dm2~10-3eV2

q2 what oscillation process is best
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
disappearance appearance
Disappearance ? Appearance?

Oscillation probability

Disappearance case

There is no place for complex phase d in UMNS to appear

Disappearance has no sensitivity on (standard) CPV

appearance
Appearance
  • Conventional nm beam (~GeV)
    • nm ne
      • Not yet discovered
    • nm  nt
      • Dominant oscillation mode
  • Neutrino factory/Beta beam (~10GeV)
    • ne  nm
    • ne  nt

Next talks

n e vs nt appearance
ne vsnt appearance

Oscillation probability (w/ CPV)

  • nm ntcase,
    • probability A∝sin22q23, 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∝sin22q13 is known to be small
    •  Large CPV effect expected

CP conserved part

CPV part

Relative effect of CPV

matter effect
Matter effect

Interactions through propagation in matter

nt

ne

nm

e-

nt

nm

ne

ne

NC

W

Z

Z

Z

X

X

X

ne

e-

X

X

X

CC

matter effect1
Relative size of effect ∝ E

Change sign when Dm2 sign change: Can probe sign

Change sign when n⇔nbar: Fake CPV effect

Matter effect
oscillation probabilities
Oscillation probabilities

3

Dm232

2

1

when

contribution from Dm12 is small

(No CPV & matter eff. approx.)

nm disappearance (LBL/Atm)

q23 and Dm232

~1

ne appearance (LBL/Atm)

q13 and Dm132

~0.5

Pure q13 and Dm132

ne disappearance (Reactor)

≪1

n m n e appearance cpv

d-d, a-a for

nmne appearance & CPV

Main

CP-odd

Solar

Matter

Matter eff.:

Sensitivity indep. from q13

(if no BG & no syst. err)

# of signal ∝ sin2q13 (Stat err∝sinq13),

CP-odd term ∝ sinq13

all mixing angle need to be non zero
All mixing angle need to be non-zero

Leading

CP-odd

d-d, a-a for

+ other terms..

Matter eff.:

CPV effect

(where sinq12~0.5, sinq23~0.7, sinq13<0.2)

Same as Kobayashi-Maskawa model which require 3x3 to incorporate CPV

23

Takashi Kobayashi (KEK), PAC07

cpv vs matter effect
CPV vs matter effect

nmne osc. probability w/ CPV/matter

295km

730km

@sin22q13=0.01

Smaller distance/lower energy  small matter effect

Pure CPV & Less sensitivity on sign of Dm2

Combination of diff. E&L help to solve.

lepton sector cp violation
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 δincluding 180°

*Could investigate CP phase with νrun only

  • Difference between νe and νeBehavior
how to do experiment
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 physics

So, now, let’s consider more on experimentation!

super beam

Decay Pipe

Focusing

Devices

Proton

Beam

Target

m

nm

p,K

Beam Dump

Super Beam

Conventional neutrino beam with (Multi-)MW proton beam (nFact)

  • Pure nm beam (≳99%)
  • ne (≲1%) from pme chain and K decay(Ke3)
  • nm/nm can be switched by flipping polarity of focusing device

Strongly motivated by high precision LBL n osc. exp.

high intensity narrow band beam off axis oa beam

Far Det.

q

Decay Pipe

Horns

Target

En(GeV)

En(GeV)

Ep(GeV)

High intensity narrow band beam-- Off-axis (OA) beam --

(ref.: BNL-E889 Proposal)

nm flux

Decay Kinematics

1

2

5

1/gp~q

  • Increase statistics @ osc. max.
  • Decrease background from HE tail
n m n m flux for cpv meas

nm

-15%@peak

nm

1021POT/yr

nm/nm flux for CPV meas.

Example

Sign flip by

just changing

horn plarity

50GeV proton

At 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

Cross sections
n e appearance search
ne appearance search

m

e

p0

  • Back ground for ne appearance search
    • Intrinsic ne component in initial beam
    • Merged p0 ring from nm interactions

31

available technologies for huge detector
“Available” technologies for huge detector

Good at low E (<1GeV) narrow band beam

LiqAr 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

Good at Wideband beam

neutrino energy e n reconstruction in water cherenkov

m-

m-

nm+ n→ m+ p+ p

nm+n→m + p

(Em, pm)

(Em, pm)

ql

qm

n

n

p

p

inelastic

QE

Neutrino Energy En reconstruction in Water Cherenkov

CC quasi elastic reaction

p

2 approaches for cpv and sign d m 2
2 approaches for CPV (and sign(Dm2) )
  • Energy spectrum measurement of appeared ne
    • Only w/ numu beam (at least early part)
    • Measure term ∝ cosd (and sind)
      • Assume standard source of CPV (d in MNS)
    • Cover 2nd oscillation maximum (higher sensitivity on CPV)
      • Higher energy = longer baseline favorable
    • Wideband beam suited
    • LiqAr TPC is better suited
  • Difference between P(numunue) and P(numubar nuebar)
    • Measure term ∝ sind
    • Not rely on the standard scenario
angle and baseline
Angle and Baseline
  • 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:

○ 2ndOsc. Max. at Measurable Energy

× Less Statistics

? Large Matter Effect

    • Short:

○ High Statistics

× 2ndOsc.Max.Too Low Energy to Measure

? Less Matter Effect

dCP=0

OA0°

dCP=90

nm flux

OA2°

dCP=270

OA2.5°

OA3°

νμ νeoscillation probability

Oscillation probability

Dm312 = 2.5x10-3 eV2

sin22q13 = 0.1

No matter effects

(E/L)

cern future possibilities
CERN future possibilities

Present accelerator complex

Various POSSIBLE scenarios

  • Under discussion
p ossible scenarios in japan
Possible scenarios in Japan

Okinoshima

Kamioka

Korea

295km

2.5deg. Off-axis

658km

0.8deg. Off-axis

1000km

1deg. Off-axis

slide42

Scenario 1

νeSpectrum

sin22θ13=0.03,Normal Hierarchy

  • Cover 1st and 2nd Maximum
  • Neutrino Run Only 5Years×1.66MW
  • 100kt Liq. Ar TPC
    • -Good Energy Resolution
    • -Good e/π0discrimination
  • Keeping Reasonable Statistics

δ=0°

δ=90°

δ=180°

δ=270°

CP Measurement Potential

Okinoshima

Beam νe

Background

3s

658km

0.8deg. Off-axis

NP08, arXiv:0804.2111

slide43

Scenario 2

  • Cover 1st Maximum Only
  • 2.2Years Neutrino+7.8Years anti-Neutrino Run 1.66MW
  • 540kt Water Cherenkov Detector

295km

2.5deg. Off-axis

<En>~0.6GeV

Kamioka

Tokai

sin22θ13=0.03,Normal Hierarchy

d=0

d=p/2

CP sensitivity

signal+BG

3s

nm+nm+ne+neBG

nm

sin22q13

nm+nmBG

deg.

Enrec

Enrec

3s

Fraction of d

nm

sin22θ13

Enrec

Enrec

K.Kaneyuki @NP08

f nal possibilities
FNAL possibilities

NOvA

700kW

15kt Liquid Scintillator

Under construction

NSF’s proposed

Underground Lab.

DUSEL

735 km

2.5 msec

810 km

MiniBooNE

SciBooNE

MINOS

NOvA

MINERvA

MicroBooNE

1300 km

~300 kton

Water Cerenkov

~50 kton Liquid Ar TPC

Project X: ~2 MW

Combination of WC and LAr

US Superbeam Strategy: Young-Kee Kim, Oct. 1-3, 2009

to realize the experiments
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!
summary
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!
slide50

Scenario 3

  • Cover 2nd Maximum @ Korea
  • Cover 1st Maximum @ Kamioka
  • 5Years ν+5Years ν Run 1.66MW
  • 270kt Water Cherenkov Detector each
  • @ Korea, Kamioka

295km

2.5deg. Off-axis

1000km

1deg. Off-axis

F.Dufour@NP08

(study is initiated by M.Ishitsuka et. al. hep-ph/0504026)

additional requirement for far detector optimization
Additional requirement forfar detector optimization
  • Proton Decay Discovery Performance
  • Realization of the huge detector
    • Test of the key components
    • Experimentally prove the detector performance
      • if necessary, good prototyping

(able to predict Huge Detector Performance well)

is important

      • Test with the beam is important

KEK started R&D for Huge Liq. Ar TPCwith ETH Zurich

 See Maruyama’s talk

constraints on d m 12 2 q 12
Constraints on Dm122, q12太陽&原子炉ニュートリノ
q 23 d m 23 2
q23, Dm232:大気ニュートリノと加速器実験

SK(1996~)

K2K(1999~2004)

q23 ~45o

Dm232 ~0.0024eV2

MINOS(2005~)

735km

M.Diwan, Venice, Mar.2009

すべて “消失”実験

54

q 13 chooz
q13の上限値原子炉反電子ニュートリノ消失実験Choozq13の上限値原子炉反電子ニュートリノ消失実験Chooz
three neutrino mixing
Three neutrino mixing.

If neutrinos have mass:

~0.03

~p/4

And sin22q13 < ~0.14

slide57
q13の測り方

原子炉ニュートリノによる13

  • 反電子ニュートリノ:<E> ~ a few MeV e消失実験
  • P(ee) = 1- sin2213・sin2(1.27m231L/E) + O(m221/m231)
  •  Almost pure measurement of q13.
  • 消失信号が小さい 系統誤差勝負

加速器ニュートリノによる13

  • ミューニュートリノ:<E> ~ O(GeV)  ne出現実験
  • P(me) = sin2q23・sin2213・sin2(1.27m231L/E) + many terms(incl. d)
  •  Appearance measurement
  •  統計(=ビームパワーx検出器サイズ)勝負

57

neutrino oscillation in 2flavor approx
Neutrino Oscillation (in 2flavor approx.)

現象

元の種類のニュートリノが減少 (“Disappearance”)

別の種類のニュートリノが出現 (“Appearance”)

振動に特徴的なエネルギー分布

  • Neutrino Mixing

mass

m1

m2

Weak eigenstates

Mass eigenstates

  • Probability to change flavor

L:flight dist、En:neutrino energy

Dm2

1-P(nmnt)

Disappearance (消失)

sin22q

L=250km, Dm232=3x10-3eV2

58

2

1

En(GeV)

Takashi Kobayashi (KEK), PAC07

Dm2

Appearance (出現)

sin22q

long baseline osc experiments

“Super Beam”

Experiments

(-)

(-)

Long baseline osc. experiments

Classification by

G.Feldman @SB WS@BNL

  • 1st phase experiments (Now)
    • Confirmation of atm. n results
      • K2K(1999~)/MINOS(2005~)/ICARUS/OPERA(2006~)
  • 2nd phase experiments (Now~10yrs)
    • Discovery of ne appearance
    • Designed & Optimized aft. SK atm n
    • ~MW beam w/ ~50kton detector
      • T2K-I (approved. 2009~)/NOnA (2009?~) / (C2GT)
  • 3rd phase experiments(10~20yrs?)
    • CP violation and mass hierarchy thru nmne app.
    • Typically Multi-MW beam & Mton detector
    • 2nd phase is critical step to go
quest for the origin of matter dominated universe
Quest for the Origin of Matter Dominated Universe

v

Water Cherenkov

One of the Main Subject of the KEK Roadmap

Discovery of

the ne Appearance

T2K

(2009~)

Discovery of

Lepton CP Violation

Proton Decay

Neutrino

Intensity Improvement

Establish

Huge Detector

Technology

Construction of

Huge Detector

Huge Detector R&D

Liquid Ar TPC

accelerator based neutrino project in japan
Accelerator Based Neutrino Project in Japan

Able to concentrate on Far Detector issuetoward the 3rd Generation Experiment after T2K startup