(Accelerator-based)Long baseline neutrino experiments

Takashi KobayashiKEK

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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

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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 3

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3 flavor mixing & oscillationilil U nn

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

0010

0

00010001

00

001

10000

cs

sc

ecssccs

scU

id

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~)

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Importance of nmne appearance

Sensitive to CPV sign of Dm13 (Mass hierarchy) thru

Matter effect

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132312sin sss d

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 En (GeV)

May2005 May2012

Tota

l PO

T (1

020)

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16

#p/w

eek(

1018

)10

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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 experimentMeasure neutrino at near siteFnear ・ snear ・ enear

Predict far detector observationNfar(E)=Posc ・ Ffar ・ sfar ・ efar

Near to Far Flux extrapolation (T2K case)

Extrapolate (Not just 1/L2!)

Far observationscompare

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 ringMC 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 remain

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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 Barrnm 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 determination28

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) Dm23

2 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 & nm disappearance

Hint on CPV and/or Mass hierarchy Future experiments for CPV&Mass hierarchy are being discussed & proposed (LoI,

EoI, ..)32