(accelerator-based) long baseline neutrino experiments takashi kobayashi kek 1 120711 ichep2012...
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(Accelerator-based)Long baseline neutrino experiments
Takashi Kobayashi
KEK
1
120711ICHEP2012@Melbourne
Contents
Introduction Players and their status Important issues in LBL experiments Results
ne appearance
nm disappearance
nt appearance Speed of neutrino
Future Summary
2
Neutrino physics Great progress in last decade
Exhibit first violation of standard “SM”: Non-zero mass Surprisingly large mixing unlike quarks
Yet unknowns & puzzles (>40yrs behind quark) Flavor mixing
Standard 3 x 3 PMNS mixing picture is correct? All three flavors participate mixing? (q13?) Why so different from quark mixing? CP is violated?
Mass Absolute mass “Unexplained lightness of the existence” Mass ordering (hierarchy)
Any additional neutrino?? Unraveling mysteries of neutrino is expected to shed light on
fundamental questions in particle physics High energy scale physics Matter dominated universe
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4
3 flavor mixing & oscillationilil U
Weak Mass eigenstates
Pontecorvo-Maki-Nakagawa-Sakata Matrix
sij=sinqij, cij=cosqij
3 mixing angles and 1 CPV phase: q12, q23, q23, d
mi: 3 masses,
Dmij2=mi
2-mj2: 2 differences
Flavor transition (oscillation)
Frequency is characterized by
Sol, Reactor (LB) Reactor (SB)Acc. LBL
1313
1313
2323
23231212
1212
0
010
0
00
010
001
0
0
001
100
0
0
cs
sc
ecs
sccs
sc
Ui
Flavor transition =Dmij
2 and off-diag. elements are non-zero
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Only upper bound on q13 No measurement of Dm13 q23 maximal? Mass hierarchy (sign of Dm31
2) No hint on CPV (Absolute mass)
Knowledge before Summer 2011T.Schwetz,M.Tortola,J.Valle, hep-ph:1103.0734v2
~2.5x10-3eV2
Long baseline oscillation experiments
Optimized for Dm2 = 4En/L=2~3x10-3eV2
nm beam of 1~10GeV from pion decay Baseline ~ several 100km
Physics nm disappearance (q23, Dm23): q23 really maximal (45deg)?? nt appearance (q23, Dm23): Definite check. Consistent w/ disappearance? ne appearance (q13, Dm13): Last key to realize CPV search Sterile neutrino search Something new!
Players1. Confirmation of SK atm n results (90s, 2000s-)
K2K(1999~2004), MINOS(2005~2012), CNGS(2008~)
2. Discovery of nue appearance (Starting ~2010s) T2K(2009~), NOvA (2013~)
3. CPV and mass hierary (20XX~) 6
Importance of nmne appearance
Sensitive to CPV sign of Dm13 (Mass hierarchy) thru
Matter effect
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132312sin sss
CPVSol term
Existence of ne appearance Non-zero (reasonable size) q13
CPV term can exist
Chance to detect CPV in the future!
LBLPlayers
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MINOS (2005~2012)
735km
Far detector ~3GeV nm beam from FNAL 120GeV MI
~350kW operation achieved (magnetized)Iron-scintillator tracker at 735km (5.4kt)
and near (980t) Physics goals
(Anti-)nm disappearance ne appearance Also measure atmospheric neutrino
Finished data taking on Apr.30, 2012 10.7x1020POT for nm
3.4x1020POT for anti-nm
4 10 E n (GeV)
May2005 May2012
Tot
al P
OT
(10
20)
10
16
#p/w
eek
(1018
)10
10
CERN neutrino to Gran Sasso (CNGS) Wide band nm beam of 10~30GeV
from CERN 400GeV SPS Detectors at Gran Sasso
732km from CERN nt appearance (+ ne appearance) First beam May 2006
OPERA (2008~) t ID by decay topology (kink) Emulsion-Counter Hybrid 150k ECC blocks ~1.25kt Accumulated 1.4x1020pot by 2011
(~1.8e20, 84% of requested in 2012)
ICARUS(Oct.2010~): 600ton LiqAr TPC (T600) 5.8x1019pot accumulated
ICARUS detector in LNGS hall B
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T2K experiment
Off-axis nm beam @ ~600MeV from J-PARC 30GeV MR 200kW achieved (>100T p/pulse)
Super-Kamiokande @ 295km Main physics goals
ne appearance nm disappearance
• Started data taking in Jan 2010• First physics results w/ full data bfr
the EQ (1.43x1020pot) in June 2011• Resumed data taking in Mar. 2012• New results w/ data until June 9,
2012 (3.01x1020pot) released (18% increase from Nu2012)
K.Sakashita
Important issues in LBL experiments (Integrated) Beam power (& detector mass) Understanding of
Beam Neutrino interaction Detector (efficiency)
for better syst. precision
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Typical basic principle of experiment
Measure neutrino at near siteFnear ・ snear ・ enear
Predict far detector observation
Nfar(E)=Posc ・ Ffar ・ sfar ・ efarNear to Far Flux extrapolation (T2K case)
Extrapolate (Not just 1/L2!)
Far observations
compare
Can measure only product
R.Snider@ICHEP
Understanding beam Flux & Near to far flux extrapolation are govened by
parent hadron (p/K..) production (p&q dist.) Beam line geometry (controllable)
Hadron production measurements have played critical role HARP @ CERN-PS (K2K, MiniBooNE) MIPP @ FNAL (MINOS) NA49/NA61 @ CERN-SPS (T2K, US program) Etc..
13NA61 (S.d.Luise@ICHEP)
B.Popov@Nu201230GeV p+C results from NA61 for T2K
Understanding cross sections Many efforts:T2K-ND, SciBooNE, MiniBooNE, MINERnA, …
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T2K-ND(p0d) NCp0 (G.Lopez@ICHEP)
T2K-ND CC (M.R.Salzgeber@ICHEP) MINERnA: s dedicated expt @FNAL-NuMI
Completed LE modeNu: 4.0e20potAnti-Nu:1.7e20potME run start in 2013
SeeParallel talk by R.SniderPoster by H.Ray
Anti-nm CCqe
CCqe tent ion btw MiniBooNE & high energy data
New Results
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T2K ne appearance results T2K reported the first indication of ne appearance
(=non-zero q13) on June 15th, 2011 w/ all data, 1.43x1020POT taken before the earthquake PRL107,041801,2011
At Nu2012, updated results w/ data taken in 2012 Here, further updated results w/ full data taken so
far, 3.01x1020POT presented (18% increase from Nu2012) See K.Sakashita’s parallel talk for detail
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Released Data (POT) ne cand
BG p-value Osc. Ana
June 15, 2011 1.43x1020
(~Mar11,2011)6 1.5±0.3 0.7%
(2.5s)# of evts
Nu2012(June) 2.56x1020
(~May15,2012)10 2.73±0.37 0.08%
(3.2s) # of evts& ShapeICHEP2012 3.01x1020
(~Jun9,2012)11 3.22±0.43 0.08%
(3.2s)
Measurements by T2K Near detectors
17See poster by
Consistency checks of BG predictions
F・ sCC measurement
Constraint on Far detector prediction
Measurements of intrinsic ne contami.
Measurements of NCp0 production
Eve nt rate is stable
T2K analysis and results
Signal:neCCqe ne+np+e-
Selection 1 e-like ring (>100MeV) No decay-e Inv. mass of 1st ring and forced-
found 2nd ring <105MeV (remove remaining p0)
Rec. En <1250MeV
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e-like (showering) ring m-like ring
MC MC
Good rejection of nm events
K.Sakashita
T2K: 11 candidate events
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K.Sakashita
T2K ne appearance results
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K.Sakashita
Attempts for detecting ne appearance
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MINOS (talk by Giles Barr) OPERA (talk by Marilisa De Serio)
• Rule out q13=0 at 2s level
• Consistent w/ T2K
Consistent w/ backgroundExcluded high Dm2 region
Both experiments are not optimized for ne appearance search
T2K nm disappearance
Data bfr EQ: 1.43e20pot (2% of approved amount)
Signal: nmCCQE: nm+nm+p 1ring m-like, 0 or 1 decay-e, pm>200MeV/c
31 events remain22
sin22q23 > 0.84Dm23
2 = 2.2~3.1x10-3eV2
90%CL region
Best fit: (sin22q23, Dm232) =(0.98, 2.65 x10-3 eV2)
MINOS nm disappearance
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Giles Barr
nm beam
Anti-nm
Atm n
Constraint on osc. params
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• Best Dm2 determination from MINOS
• All results from SK, MINOS, T2K are consistent
Giles Barr
MINOS results
OPERA nt appearance Status of the analysis
2 candidate events so far ( expected 2.1 with 0.2 background events)
A few more events are under study.
Progress in estimating detection efficiency and BG.
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First cand. (t1had kink) reported in 2010
2nd Cand (t3h) reported in June 2012
Parallel talk by Marilisa De Serio
nt appearance from SK atm n
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Y.Hayato
Speed of neutrino
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MINOS measurement (Giles Barr)
S.Bertolucci @ Nu2012
S.Bertolucci @ Nu2012
All consistent w/ c
Near future Improve significance of ne appearance is of
urgent importance Precision measurements of BOTH
appearance & disappearance are important
Experimental determination of Dm13 is also very important
Also, first trial of mass hierarchy determination 28
Acc ne appearance measurement Pme=f(s12s23s13sd)nm disappearance measurement Precise q23
Reactor ne disappearance measurement Precise q13
Could give hint on dCP
Stat err only!
Stat err only!
sin22q23=1 fixed
Unofficial plot (Okumura/TK)
T2K expected stat error at750kW x 5x107s
G.Fogli@Nu2012
Already similar precision!
PlayersT2K, NOnA, MINOS+(MINOS det + 700kW NOnA
optimized higher energy beam), (SK), etc
See G.Barr’ s talk
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NOvA (2013~)
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Optimized experiment for ne appearance
FNAL NuMI off-axis beam Power upgrade 320kW700kW
Recycler: anti-proton proton Rep cycle 2.2s 1.33s
New 14kton liquid scintillator fine grained detector @810km
Construction for power upgrade and detector on-going Plan to start meas. from May 2013
First trial of hierarchy determination See Parallel talk by Jonathan M. Paley2 5 (GeV)
Toward CPV&Mass hierarchy Large q13 opened possibility of CPV search (& mass hierarchy
determination) BUT, not necessarily means EASY (Relative CPV effect 1/sin∝ q13) Expected CP effect ~ 20% at sin22 q13 &sind=1 (~2% @ sind=0.1) at
1st osc. max. Order of magnitude higher statistics from present generation
experiments High intensity beam (~MW or higher) High sensitivity huge detector
Should also capable for proton decay detection
Requirement on systematic uncertainty becomes severe Hadron prodcution Xsec meas. Good near detector
as far as possible Matter effect is larger at
larger L (E) Experiment to determine
Mass hierarchy could be realized
earlier w/ very long baseline
(>1000km) 30
Genuine CPV
Asym by matter effect
Example of size of effects
295km2300km
Asymmetry btw app. prob. for n and anti-n
World efforts to formulate future direction US: LBNE
Reconfigured to phased approach:10kt on surface first DOE CD-1 review in fall 2012
Go underground if enough additional fund become available
EU EoI of LBNO, CERN-SPSC-2012-021
(SPSC-EOI-007), is submitted to/received by CERN SPSC (June 2012)
Excellent sensitivity on hierarchy Japan: Two options w/ J-PARC
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Y.K.Kim
T.Nakadaira@Nu2012
LBNE
Project X (8GeV LINAC +MI)
@Homestake
US
Summary ne appearance
Evidence obtained by T2K P-value 0.7%(2.5s) (2011) 0.08%(3.2s) (2012) Opened possibility of CPV/Hierarchy meas.
2s level from MINOS nt appearance
2 signal candidates w/ 0.2 BG in OPERA 3.8s level excess in SK atm nt enhanced analysis
nm disappearance q23 most constrained by SK atm : n sin22q23 > 0.93~0.95 (@90%CL)
Dm232 by MINOS (2.39+0.09-0.11)x10-3eV2 (4% meas)
Speed of neutrino consistent w/ light Future
Near: Improve ne appearance significance precision measurements of ne
appearance & n m disappearance Hint on CPV and/or Mass hierarchy
Future experiments for CPV&Mass hierarchy are being discussed & proposed (LoI, EoI, ..) 32