Long Baseline Neutrino Oscillation Experiments

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


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!


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


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,


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


• 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


The SNO Experiment


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


SNO Neutrino flux

ssm = 5.05+1.01-0.81

sno = 5.09+0.44-0.43

+0.46-0.43

or e


Interpretation

combination of all experimental and solar model information


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


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


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


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


KamLAND Results• Measure rate and energy

spectrum of reactor neutrinos

• Clear confirmation of LMA


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


The SuperKamiokande Experiment

• H2O Cherenkov Detector– Proton decay

– Neutrino interactions


SuperK Results

• Atmospheric neutrinos

• Muon neutrinos are missing!


The K2K Experiment

• Baseline: 250 km

• 1020 protons on target E = 12 GeV

• Neutrino energy: 1.4 GeV

Prototype of a Long-Baseline-Experiments


K2K Results


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

• Sagitta:10 km

• >1 km wide at destination

The MINOS Experiment


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


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


The MINOS Mural


Upper steel layer

Lower steel layerScintillator planealternating orientations 90o

in successive planes

2-m wide, 0.5-inch thicksteel plates

MINOS planes


Installation• Impressive progress

– 80% personnel achieve 120% of the work

– 400+ out of 484 planes are installed

– normal data taking during installations


• 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


• 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


μ Disappearance Results


First Neutrino Event

Y

z

t

from abovefrom below

Upward going Muon!


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


• 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


~ 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


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


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


“ Long decaysreconstruct kink topology

“ Short decays detect large impact parameter track

Loose cut to reject low momentum tracks

OPERA Candidates


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


• Physics

– Nucleon Decay

– Atmospheric Neutrinos

– Solar Neutrinos

– Beam Neutrinos (CNGS)

• Technology– Liquid Argon TPC

– 3D tracking

– Scintillation light & PMTs trigger readout


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


ICARUS Sensitivity

atmospheric beam

Sensitivity similar to OPERA!


Sub-dominant Oscillation Modes• Main oscillation mode known

– solar:

– atmospheric:

• Measure sub-dominant oscillation mode

or e

e

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


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


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


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!


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


Neutrino Factory• Muon storage ring: The Ultimate Neutrino Source


Neutrino Factory Physics


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)

Long Baseline Neutrino Oscillation Experiments

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