Long Baseline Neutrino Oscillation Experiments

Alfons WeberRAL/University of Oxford

RAL -Southampton Meeting

RAL

February 7, 2003

A. Weber LBL Experiments 2

Contents• Introduction• Long baseline experiments

– SNO– KamLAND– SuperKamiokande– K2K– MINOS– OPERA– ICARUS

• The Future– Off-Axis Experiments– Neutrino Factories

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Introduction• Several indication for neutrino oscillations

– Solar neutrino problem• Homestake, SAGE, GALLEX

• Kamiokande, Super-Kamiokande, SNO

– Atmospheric neutrino problem• Kamiokande, IMB, Frejus, NUSEX, Soudan 2, SuperK

– LSND effect• LSND, KARMEN

• New precision experiments are needed!– replace natural with man-made neutrino source

– tune oscillation distance and energy to problem

• Find out what the Neutrino oscillation matrix looks like!

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Neutrino Mixing• Assume that neutrinos do have mass:

– mass eigenstates weak interaction eigenstates

• Analogue to CKM-Matrix in quark sector!

12 13 13 12 13 1

23 12 12 13 23 12 23 12 13 23 13 23 2

23 12 12 23 13 12 23 23 12 13 13 23 3

e

i i

i i

c c c s s

c s e c s s c c e s s s c s

s s e c c s c s e c s s c c

weak“flavour eigenstates”

Mass eigenstatesm1, m2, m3Unitary mixing matrix:

3 mixing angles & 1 complex phase

2ijmit cos( ), sin , Mischungswinkel und Massenunterschiedij ij ij ij ijc s (θ ) θ Δm

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Neutrino Oscillations• If mass and weak eigenstates are different:

• Neutrino is produced in weak eigenstate

• It travels a distance L as a mass eigenstate

• It will be detected in a (possibly) different weak eigenstate

• Simplified model with two neutrinos only:

22 2 1.27

( ) sin (2 )sine

m LP

E

1

2

cos sin

sin cose

or e 1 2,

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Oscillation Signature2

2 2 1.27( ) 1 sin (2 )sin

m LP

E

2 3 23 10m eV

735 kmL

No effect!

measures m2

Smeared by resolution

P ~ 1/2

2 Em

L

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• Different detectors (Super-K, Homestake, Gallex, Sage,…)

• Different detection thresholds

• All detectors observe neutrinoneutrino deficit

• Reasons:– magnetic moment

– neutrino oscillations

The Solar Neutrino Problem

0.2 7.0 MeVthresE

Not enough electron neutrinos from the sun

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The SNO Experiment

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Neutrino Reactions in SNO

NCxx

npd

ES -- ee x x

- few events- mainly sensitive to e, (less to and )- strong angular correlation

- well measured e energy spectrum- weak angular dependence 1-1/3cos()- e only

- same cross section for all neutrinos- measures total 8B -flux of the sun

CC-epd e p

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SNO Neutrino flux

ssm = 5.05+1.01-0.81

sno = 5.09+0.44-0.43

+0.46-0.43

or e

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Interpretation

combination of all experimental and solar model information

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KamLAND• 1 kton LScint. detector in

the Kamioka cavern– 1300 17” fast PMTs

– 700 20” large area PMTs

– 30% coverage

• H2O veto counter

• Multi-hit dead time-less electronics

• Neutrinos from Japanese nuclear power plants (~160 km)

• Δm2 sensitivity 710-6eV2

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S.Dazeley, K.Eguchi, S.Enomoto, K.Furuno, Y.Gando, J.Goldman, H.Hanada, H.Ikeda, K.Ikeda, K.Inoue, K.Ishihara, W.Ito, T.Iwamoto, H.Kinoshita,

T.Kawashima, M.Koga, T.Maeda, T.Mitsui, M.Motoki, K.Nakajima, M.Nakajima, T.Nakajima, I.Nishiyama, H.Ogawa, K.Oki, T.Sakabe, I.Shimizu,

J.Shirai, F.Suekane, A.Suzuki, O.Tajima, T.Takayama, K.Tamae, H.Watanabe Tohoku University

T.Taniguchi KEK

T.Chikamatsu Miyagi Gakuin Women's School

H.Higuchi Tohoku-Gakuin University

Y-F.WangIHEP, Beijing

J.Busenitz, Z.Djurcic, K.McKinny, D-M.Mei, A.Piepke University of Alabama

B.Berger, R.N.Cahn, Y.D.Chan, X.Chen, S.J.Freedman, B.K.Fujikawa, K.T.Lesko, K.-B.Luk, H.Murayama, D.R.Nygren, C.E.Okada, A.W.Poon, H.M.Steiner

LBNL/UC BerkeleyL.Hannelius, G.A.Horton-Smith, R.D.McKeown, J.Ritter, B.Tipton, P.Vogel

California Institute of TechnologyC.E.Lane

Drexel University J.Learned, J.Maricic, S.Matsuno, S.Pakvasa

University of HawaiiS.Hatakeyama, R.C.SvobodaLouisiana State University

B.D.Dieterle, C.GregoryUniversity of New Mexico

J.Detwiler, G.Gratta, H-L.Liew, D.Murphree, N.Tolich, Y. UchidaStanford University

Y.Kamyshkov, W.Bugg, Y.Efremenko, H.Cohn, A.Weidemann, S.Berridge, M.Schram, M.Batygov, Y.Nakamura

University of TennesseeL.Braeckeleer, C.Gould, C.L.HoeM.Hornish, H.Karwowski, D.Markoff, J.Messimore,

K.Nakamura, R.Rohm, N.Simmons, W.TornowTUNL

KamLAND Collaboration

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nepe•Large(r) cross-sectionLarge(r) cross-section

•Specific signatureSpecific signature

•ee++ kinetic kinetic energy energy (<8 MeV)(<8 MeV)

•2 annihilation 2 annihilation

γγss (0.5 MeV)(0.5 MeV)

•neutron neutron

capturecapture

(2 to 8 MeV)(2 to 8 MeV)

epnemMMEE )(

Neutrino energy measuredNeutrino energy measuredfrom positron energyfrom positron energy

Detecting Neutrinos

~2 events / day

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So… what does an event look like ?So… what does an event look like ?

Time: Time: RedRed soon, soon, Blue Blue latelate Charge: Charge: RedRed a lot, a lot, BlueBlue littlelittle

KamLAND Event

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KamLAND Results• Measure rate and energy

spectrum of reactor neutrinos

• Clear confirmation of LMA

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Atmospheric Neutrinos• Atmosphere is bombarded

by cosmic rays– Protons (H+)

– nuclei (He, Li, …)

– photons

– …

• some particles (1&2) produce hadronic shower

• Neutrino ratio

ee

2e

Nr

N

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The SuperKamiokande Experiment

• H2O Cherenkov Detector– Proton decay

– Neutrino interactions

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SuperK Results

• Atmospheric neutrinos

• Muon neutrinos are missing!

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The K2K Experiment

• Baseline: 250 km

• 1020 protons on target E = 12 GeV

• Neutrino energy: 1.4 GeV

Prototype of a Long-Baseline-Experiments

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K2K Results

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• NuMI beam to Soudan in MN (distance 735 km)

• Sagitta:10 km

• >1 km wide at destination

The MINOS Experiment

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MINOS Detectors• There are 3 MINOS Detectors

– Near detector @ FNAL (ND)

– Far detector @ Soudan (FD)

– Calibration detector @ CERN (CalDet)

• Magn. steel-scintillator-tracking-calorimeter– alternating layers of steel and scintillator strips

5.4 kton

12 ton0.9 kton

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Photo by Jerry Meier

• Where? 27. Underground level of the Soudan Underground Mine State Park

• Operated by the University of MN for the DoE

• ideal location • Tourist attraction: 40.000/year

• well maintained• non operated mine

MINOS cavern in blue

MINOS Far Detector

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The MINOS Mural

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Upper steel layer

Lower steel layerScintillator planealternating orientations 90o

in successive planes

2-m wide, 0.5-inch thicksteel plates

MINOS planes

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Installation• Impressive progress

– 80% personnel achieve 120% of the work

– 400+ out of 484 planes are installed

– normal data taking during installations

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• Several channels to analyse neutrino oscillations– T-Test = #CC / #NC– – e appearance (–

• Combination of all analysis will reveal mixing parameters– m2

– sin22– flavour

appearance

disappearance

μ μ

hadrons

5 m

μ

hadrons

μ

1.5 m

MINOS Oscillation Physics

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• Select μ charge current events and reconstruct neutrino energy

• Energy resolution:

• Compare energy spectrum in near and far detector

• Measure m2 and sin22

hEEE

range, B field calorimetric

EEE

pp

hh /%60/

%10/

m2

sin22

μ CC Energy Analysis

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μ Disappearance Results

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First Neutrino Event

Y

z

t

from abovefrom below

Upward going Muon!

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Atmospheric Neutrinos• Look for high energy muons

(>1 GeV)• 4 years of data taking

(18 kton years)• measure stopping and through-

going muons• Energy measurement by

magnetic field• Separation of neutrinos and

anti-neutrinos!

un-oscillated spectrum

m2=10-3,sin2(2)=1.0

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• CERN SPS– Ep = 400 GeV

– 4.8*1013 ppp

– cycle 6 - 27.6 sec

– 7.6*1019 pot/year

• Baseline: 730km

• <E > = 17 GeV

• optimised for neutrino appearance

CNGS Beam

CERN Neutrinos to Grand Sasso

• Experiments– ICARUS

– OPERA

– try find by searching for decay kink

– nuclear emulsion

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~ 10

m

spectrometerMagnetised Iron Dipoles

Drift tubes and RPCs

target and decay detectorEach “super-module” is

a sequence of 24 “modules” consisting of - a “wall” of Pb/emulsion “bricks”- planes of orthogonal scintillator strips

scintillator strips

brick wall

module

brick(56 Pb/Em. “cells”)

8 cm (10X0)

super module

The OPERA Experiment

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Emulsion-Scintillator strip Hybrid Target

•Tracker taskselect bricks efficiently

• High scanning power + low background allow coarse tracking

Selected bricks extracted daily

using dedicated robot

Sampling by Target Tracker planes ( X,Y )

Brick wall

10 c

m

Selected brick

Event as seen by the target tracker

0 max

p.h.

OPERA Target Section

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Origami packed ECC brick for OPERA

Vacuum packing• Protection against light

and humidity variations.• Keep the position between

films and lead plates.• Vacuum preserved over

10 years

10X0 ( 56 emulsion films )

12.5cm235k bricks for 3 super modules

OPERA Emulsion Brick

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“ Long decaysreconstruct kink topology

“ Short decays detect large impact parameter track

Loose cut to reject low momentum tracks

OPERA Candidates

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OPERA90 % CL in 5 years

OPERA: m2

* assuming the observation of a number of events corresponding to those expected for the given m2

(mixing constrained by SuperK)

years P3 P4

3 93% 83%

5 96% 91%

Probability to observe SuperK signal

90 % CL limits * m2 ( 10-3 eV2 )

1.5 3.2 5.0

Upper limit 2.1 3.8 5.6

Lower limit 0.8 2.6 4.3(U - L) / (2*True) 41 % 19 % 12 %

Nτ / year 0.82 2.82 3.66

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• Physics

– Nucleon Decay

– Atmospheric Neutrinos

– Solar Neutrinos

– Beam Neutrinos (CNGS)

• Technology– Liquid Argon TPC

– 3D tracking

– Scintillation light & PMTs trigger readout

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2

El.m. shower

Full 2D View from the Collection Wire Plane

2 4 6 1812Wire coord. (m)

2Drift coord. (m)

Zoom views

1

32

2

3

stop and decay in e

Detail of a long (14 m) track with -ray spots

El.m. shower

T600 test @ Pv: Run 201 - Evt 12

1

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ICARUS Sensitivity

atmospheric beam

Sensitivity similar to OPERA!

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Sub-dominant Oscillation Modes• Main oscillation mode known

– solar:

– atmospheric:

• Measure sub-dominant oscillation mode

or e

e

P ( e) = P1 + P2 + P3 + P4

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Measuring e Oscillations• Needs

– low e beam contamination

– narrow band beam (suppresses NC contamination)

• NuMI Off-Axis– Beam already there

e (|Ue32| = 0.01) e background

NC (visible energy), no rejection

spectrum

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Detector Options• Detector on Surface

– but 10-5 duty factor

• Technologies (low Z)– MegaMINOS

– Liquid Scintillator

– Liquid Argon

– RPCs

• Requirements– good sampling– max: mass/radiation length– CHEAP!!!!!

(20 kton, 400k ch)

• Physics reach– oscillation probability

around 10-3

electron = fuzzy track

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J2K: JHF-SuperK

• Phase II– Increase beam power: 4 MW– HyperKamiokande: 1 Mton

• Possibility of measuring CP-violation, if parameters are right!

• No need for -factory?

• New beam from JAERI– 50 GeV, 0.77 MW– 3.3*1014 ppp / 3.3 sec

• Phase I– approved– start operation 2007

• Detector exists!

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SuperBeam Physics• CP violation (phase II)• Sensitivity (phase I)

μ disappearance (1 year)

212 12

13

( ) ( )

( ) ( )

sin 2sin

4 sin

eeCP

ee

P PA

P P

m L

E

223

2 4 223

2 313

(sin 2 ) 0.01

( ) 2 10 eV

sin 2 10

m

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Neutrino Factory• Muon storage ring: The Ultimate Neutrino Source

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Neutrino Factory Physics

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Summary• Present

– K2K (re-starting now)

– KamLAND (one year of data taking)

• Future– MINOS (cosmics 2001, beam

2005)

– OPERA (beam 2007)

– ICARUS (2005, partially approved)

– JHF-SuperK (2007, not yet approved)

– NuMI off-axis (beam 2005, detector 2007+)

• Science fantasy– Neutrino Factories (2010, at the earliest)