Transcript スライド 1

Future Prospect of Accelerator-based Neutrino
Oscillation Experiments
and other next generation experiments
Two of the essential gradients of lepto-genesis
• CP violation
• D(B-L) 0 Majorana
1
3 ‘slits’ interferometer
- possibility of CP violation in nm→ne
Interferences
3 ‘slits’
n3
n1
n3
nm
n2
n2
n3
ne
2
1
(
m

m
1 )L
U*e3 Um3 Ue1U*m1 sin 2 3
4E n
Dm2~3 x 10-3
2
1
(
m

m
*
*
2
3
2 )L
ne Ue3 Um3 Ue 2 Um 2 ) sin
4E n Interference
Comparable amplitudes
n anti-n ?
n1
n2
n1
production
(m 22  m11 )L
ne U Um 2 Ue1U ) sin
4E n solar,Kamland
*
e2
detection
*
m1
2
-5
Dm2~8 x 10
2
Importance of nm → n e Appearance
d : CP Violation in Lepton Sector
in 3 generations scheme
Pab = d ab  4 Re(U a*iU biU ajU b*j ) sin 2
(m 2j  mi2 ) L
 2 Im(U a*iU biU ajU b*j ) sin
(m 2j  mi2 ) L
j i
j i
ne disappearance 1- Pee : a=b |Uai| 2
4 En
2 En
Real
nmne at Dm2 ~ 3 x 10-3 eV2 ：interference of two Dm2’s
→( small Ue3 small Dm122 ) Two comparable terms → CPV
CPV  sinq12 sinq23 sinq13 Dm212 (L/E) sind
Solar and Atmospheric n
Solar LMA solution→ (large q12, relatively large Dm212)
Near max. mixing in atmospheric (q23~p/4)
3
Searches for non-zero q13
q13 with reactor experiments
• <En> ~ a few MeV  Disappearance
• P(nene) = 1- sin22q13・sin2(1.27Dm231L/E) + O(Dm221/Dm231)
 Almost pure measurement of q13 with negligible matter effect.
q13 with accelerator experiments
• <En> ~ O(GeV)  appearance experiments
• P(nmne) = 1- sin2q23・sin22q13・sin2(1.27Dm231L/E) + many terms
 Appearance measurement of q13.
 P(nmne) also depends on d and mass hierarchy.
4
Current Proposals on Reactor Experiments
Reactor q13 exp. (2007)
Double Chooz
approved
Daya bay
Reno
Angra
1st generation: sin2(2q13)~0.02-0.03
2nd generation: sin2(2q13)~0.01
•
2006
Acc LBL
exp. and Reactor q13 exp. are complementary.
– Appearance signal versus Disappearance signal.
– Statistics Limited versus Systematic Limited
– Large CPV effect versus Pure q13 effect.
– Similar Time scale (~2010)
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3-flavor Oscillation (simplified)
m3
Oscillation Probabilities when
2
Dm122  Dm23
 Dm132
 q23 :nm disappearance
m2
m1
(
2
Pm  x  1  cos 4 q13  sin 2 2q 23  sin 2 1.27Dm23
L / En
 q13:ne appearance
common
(
2
Pm e  sin 2 q 23  sin 2 2q13  sin 2 1.27Dm13
L / En

6

ne appearance probability at L/E ~ 103 (km/GeV)
P(nm  ne) = 4C13 S13 S 23 sin 2  31
2
2
2
q13
 8C13 S12 S13 S 23 (C12C23 cosd  S12 S13 S 23 ) cos 32 sin  31 sin  21
2
CP conserving
 8C13 C12C23 S12 S13 S 23 sin d sin  32 sin  31 sin  21
2
 4S12 C13 (C12 C23  S12 S 23 S13  2C12C23 S12 S 23 S13 cosd ) sin 2  21
2
2
2
2
2
2
2
CP
solar n
aL
matter effect
 8C13 S13 S 23 (1  2S13 ) cos 32 sin  31
4E
mass hierarchy
ij = Dmij2 L / 4 E , Sij=sinqij, Cij=cosqij
d  -d, a  -a for nmne
L : flight length, E : neutrinoenergy,
2
2
2
2
Dmij2  mi2  m 2j , mi : mass eigenvalues
Small numbers
• S13
• sinΦ21 ~ 0.03

 E  L 
aL


  ~ 2L
= 7.6  
3 
4E
 [ g / cm ]  [GeV ]  4E 
7
nm → ne Appearance Measurements
•
•
L/E~3 x 102 (km/GeV)
Three contributions
1 Term which is same for neutrinos and anti-neutrinos
2 CP violating term (constant in E)
3 Matter effect ( proportional to L or E at constant L/E)
• It is almost impossible to change distance or neutrino energy
To get 2+3
1. Compare Neutrinos and Anti-neutrinos
2. Compare with reactor data
CPV
Make matter effect small (where 2 >3)
Low energy and relatively short distance
Mass hierarchy Compare with higher energy measurements 3
8
nmne oscillation probability in sub-GeV neutrinos
sin22q13=0.01
total
q13
CP
CP
solar
matter
Depends on many
parameters
9
Accelerator Neutrinos
Near future
T2K
Nova
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T2K Collaboration
• 12 Countries
– Canada, France, Germany, Italy, Japan
– Korea, Poland, Russia, Spain,
– Switzerland, UK, USA
60 Institutes, 300 Ph.D. members
Still growing
Proposed in 2000, budget approved in 2004
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Non-zero mass of neutrinos !
Flavor Physics esp. history of neutrino studies show full of surprises
( Kamiokande for Kamioka Nucleon decay Experiment ! )
• Emphasis lepton ID and the determination of En
• En and Detector technology
1. Look for un-expected in precision measurements of oscillation
parameters
• 3 generation frame-work (paradigm) ?
• Consistency of Dm2 in disappearance and appearance processes
• Sub-process of flavor changing process ( in addition to oscillation)?
• Oscillation pattern
2. ne appearance
• The last mixing to be found
• q23~45o q12~34o, test q13 to 3o
• Determine future direction of neutrino experiment
• Lead to only one practically possible test of CPV in leptons
• Complex phase in mixing in light neutrinos → leptogenesis?12
Main features of T2K
The distance (295km) and Dm2 (~2.5x10-3 eV2 )
1. Oscillation max. at sub-GeV neutrino energy
– sub-GeV means QE dominant
• Event-by event En reconstruction
– Small high energy tail
• small BKG in ne search and En reconstruction
2.
Proper coverage of near detector(s)
– Cross section ambiguity
3.
Analysis of water Cherenkov detector data has accumulated
almost twenty years of experience
– K2K has demonstrated BG rejection in ne search
– Realistic systematic errors and how to improve
4.
Accumulation of technologies on high power beam
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Beam energy
QE is the best known process
1
10
En
14
Narrow intense beam: Off-axis beam
振動確率＠
Dm2=3x10-3eV2
Anti-neutrinos by
Super-K.
reversing Horn current
q
Decay Pipe
nm flux
TargetHorns
En (GeV)
p decay Kinematics
OA0°
OA2°
OA2.5°
0°
1
OA3°
2°
2.5°
3°
0
0
2
5
pp (GeV/c)
8
 Quasi Monochromatic Beam
Tuned at oscillation maximum
Far/near ‘simpler’ to evaluate
Statistics at SK
(OAB 2.5 deg, 1 yr, 22.5 kt)
~ 2200 nm tot
~ 1600 nm CC
ne ~0.4% at nm peak
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Quasi-Elastic process nm + n → m + p
n
E n rec =
m
q
(Em, pm)
m
m N E m  m m2 2
m N  E m  p m cosq m
dE ~ 60 MeV dE/E ~ 10%
p
QE
inelastic
CC 1p
nm + n → m + p + p
qm
n
En (reconstructed) – En (true)
p’s p
NC 1p
nm + n → n + p + p’s
n
-
m
(Em, pm)
p’s p
n
16
PID in SK
m-like
e-like
e
m
17
18
19
ne appearance : q13
Off axis 2 deg, 5 years
Dm
2
CHOOZ excluded
at
Off axis 2 deg, 5 years
sin22q13>0.006
sin22q13
Estimated background in Super-K
nm
ne
total
Signal
(~40% eff.)
10.7
1.7
0.5
24.9
114.6
139.5
10.7
1.7
0.5
24.9
11.5
36.4
20
nm
ne
(NC p0
beam
0.1
12.0
0.01
12.0
sin22q13
Signal +
BG
Sensitivity to q13 as a fuction of CP-phase d
d
d
KASKA 90%
KASKA 90%
(NuFact04)
(NuFact04)
sin22q13
d →-d for n →anti-n
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Disappearance
En reconstruction resolution
 Good resolution of En determination is critical to observe depth
of the dip (measure of sin22q)
dE~60MeV
<10% meaurement
non-QE
resolution
QE
inelastic
1-sin22q
En (reconstructed) – En (true)
Dm2
+ 10% bin
High resolution : less sensitive to systematics
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Precision measurement of q23 , Dm223
possible systematic errors and phase-1 stat.
•Systematic errors
• normalization (10%（5%(K2K))
• non-qe/qe ratio (20% (to be measured))
• E scale
(4% (K2K 2%))
• Spectrum shape (Fluka/MARS →(Near D.))
• Spectrum width (10%)
OA2.5o
d(sin22q23)~0.01
d(Dm223) <1×10-4 eV2
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T2K Physics Sensitivity
ne appearance
(Strong d dependence )
nm disappearance
Stat. only
Daya Bay 90%
(NuFact04)
CHOOZ
90%
sin22q13
>10 times improvement from CHOOZ
Neutrino ↔ Anti-neutrino, Reactor
(OA2.5)
--68%CL
--90%CL
--99%CL
Goal
d(sin22q23)~0.01
(0.08 MINOS EPS2007)
2
d(Dm232)~<5×10-5 eV24
Status of JPARC
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J-PARC Facility
Materials and Life Science
Experimental Facility
Hadron Beam Facility
Nuclear
Transmutation
500 m
Neutrino to
Kamiokande
Linac
(350m)
3 GeV Synchrotron
(25 Hz, 1MW)
50 GeV Synchrotron
(0.75 MW)
J-PARC = Japan Proton Accelerator Research Complex
Joint Project between KEK and JAERI
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From Linac
to 3 GeV
3 GeV
Extraction Point
From 3 GeV to
Materials and Life
Middle of
Linac Tunnel
JPARC
Neutrino
Tunnel
Upstream of
Linac Tunnel
Tunnel
Tour
50 GeV Tunnel
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The Neutrino Beam-Line
Target-Horn System
Target Station
Muon
Monitoring Pit
Final
Focusing
Section
295km to
Super-Kamiokande
Preparation Section
100m
SCFM at ARC Section
Near Neutrino Detector
Beam Dump
Decay Volume
28
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Full Reconstruction (October 2005 – April 2006)
~6000 ID PMTs were produced from 2002 to 2005 and were mounted
from Oct.2005 to Apr.2006.
All those PMTs were
packed in acryic and
FRP cases.
Mount PMTs on a floating floor.
Pure water was supplied and SK-III data taking
has been running since July 11, 2006.
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Schedule of T2K
2004
K2K
2005
2006
2007
2008
2009
T2K construction
SK full rebuild
Linac
MR
April 2009
n commissioning
• Possible upgrade in future
• 4MW Super-J-PARC + Hyper-K ( 1Mt water Cherenkov)
– CP violation in lepton sector
– Proton Decay
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Next step
Many possibilities
• Intensity Upgrade of MR
• R/D for upgrade/replacement of SK with a new hyper
massive detector
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CPV and mass hierarchy
IF q13 has reasonable value
Funding agency
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CP Asymmetry
ACP
P(n m  n e )  P(n m  n e )
P' r r  P ' r r

=
P(n m  n e )  P(n m  n e ) P' r r  P ' r r


2 P '2
(d   d  
= A' 1  2
2
 P'  P '

P' P'
A' 
,
P' P'
r  r
r  r
d 
, d 
r
r
(rσ =
σe
σμ
, r =
e
cross section, detection efficiencies ratios for e/m
differences in neutrino and anti-neutrino
Studied by T.Kobayashi33
m
)
Contamination of wrong sign components
nm beam
nm beam
right sign
wrong sign
Rate for nm is factor ~3 smaller than anti-nm due to cross section.
34
Cross sections
35
CP asymmetry in T2K
d=p/4
q12=p/8
matter
Both correction need to be
estimated at ~10% level
, , 
Pure CPV
,, cor.
ACP~Aobs-0.04+0.1
matter corr.36
Water Cherenkov Detector
1st Phase (2009~, ≥5yrs)
Super-Kamiokande(22.5kt)
2nd Phase (201x~?)
Hyper-Kamiokande(~540kt)
Proton decay
e+π0
νK+
Reach: tp(e+p0)/B ~ 1035 yr
tp(nK+)/B ~ 1034 yr
and other modes
37
Other Possible choice
?
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Sensitivity for CPV in T2K-II
4MW, 540kt
2yr for nm
6~7yr for nm
CHOOZ excluded
sin22q13<0.12@Dm312~3x10-3eV2
Dm212=6.9x10-5eV2
Dm322=2.8x10-3eV2
q12=0.594
q23=p/4
stat+5%syst.
stat+2%syst.
(signal+BG) stat only
ACP
2
Dm12
sin 2q12


 sin d
4 En sin q13
no BG
signal stat only
stat+10%syst.
T2K 3 discovery
T2K-I 90%
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3 CP sensitivity : |d|>20o for sin22q13>0.01 with 2% syst.
Proton Decay may be there, just around the corner
Ultimate GUTs phenomena
2.9x1030 yr (‘minimal’ SUSY SU(5) )
Proton decay limit from Super-K
~100k ton year already
40
T2K to Korea ?
Korea
L=1000-1200km,
q =1.0-4.0
J-PARC
41
hep-ph/0607255
Nova at FNAL
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