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
A. Weber LBL Experiments 3
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!
A. Weber LBL Experiments 4
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
A. Weber LBL Experiments 5
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,
A. Weber LBL Experiments 6
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
A. Weber LBL Experiments 7
• 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
A. Weber LBL Experiments 8
The SNO Experiment
A. Weber LBL Experiments 9
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
A. Weber LBL Experiments 10
SNO Neutrino flux
ssm = 5.05+1.01-0.81
sno = 5.09+0.44-0.43
+0.46-0.43
or e
A. Weber LBL Experiments 11
Interpretation
combination of all experimental and solar model information
A. Weber LBL Experiments 12
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
A. Weber LBL Experiments 13
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
A. Weber LBL Experiments 14
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
A. Weber LBL Experiments 15
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
A. Weber LBL Experiments 16
KamLAND Results• Measure rate and energy
spectrum of reactor neutrinos
• Clear confirmation of LMA
A. Weber LBL Experiments 17
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
A. Weber LBL Experiments 18
The SuperKamiokande Experiment
• H2O Cherenkov Detector– Proton decay
– Neutrino interactions
A. Weber LBL Experiments 19
SuperK Results
• Atmospheric neutrinos
• Muon neutrinos are missing!
A. Weber LBL Experiments 20
The K2K Experiment
• Baseline: 250 km
• 1020 protons on target E = 12 GeV
• Neutrino energy: 1.4 GeV
Prototype of a Long-Baseline-Experiments
A. Weber LBL Experiments 21
K2K Results
A. Weber LBL Experiments 22
• NuMI beam to Soudan in MN (distance 735 km)
• Sagitta:10 km
• >1 km wide at destination
The MINOS Experiment
A. Weber LBL Experiments 23
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
A. Weber LBL Experiments 24
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
A. Weber LBL Experiments 25
The MINOS Mural
A. Weber LBL Experiments 26
Upper steel layer
Lower steel layerScintillator planealternating orientations 90o
in successive planes
2-m wide, 0.5-inch thicksteel plates
MINOS planes
A. Weber LBL Experiments 27
Installation• Impressive progress
– 80% personnel achieve 120% of the work
– 400+ out of 484 planes are installed
– normal data taking during installations
A. Weber LBL Experiments 28
• 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
A. Weber LBL Experiments 29
• 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
A. Weber LBL Experiments 30
μ Disappearance Results
A. Weber LBL Experiments 31
First Neutrino Event
Y
z
t
from abovefrom below
Upward going Muon!
A. Weber LBL Experiments 32
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
A. Weber LBL Experiments 33
• 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
A. Weber LBL Experiments 34
~ 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
A. Weber LBL Experiments 35
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
A. Weber LBL Experiments 36
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
A. Weber LBL Experiments 37
“ Long decaysreconstruct kink topology
“ Short decays detect large impact parameter track
Loose cut to reject low momentum tracks
OPERA Candidates
A. Weber LBL Experiments 38
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
A. Weber LBL Experiments 39
• Physics
– Nucleon Decay
– Atmospheric Neutrinos
– Solar Neutrinos
– Beam Neutrinos (CNGS)
• Technology– Liquid Argon TPC
– 3D tracking
– Scintillation light & PMTs trigger readout
A. Weber LBL Experiments 40
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
A. Weber LBL Experiments 41
ICARUS Sensitivity
atmospheric beam
Sensitivity similar to OPERA!
A. Weber LBL Experiments 42
Sub-dominant Oscillation Modes• Main oscillation mode known
– solar:
– atmospheric:
• Measure sub-dominant oscillation mode
or e
e
P ( e) = P1 + P2 + P3 + P4
A. Weber LBL Experiments 43
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
A. Weber LBL Experiments 44
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
A. Weber LBL Experiments 45
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!
A. Weber LBL Experiments 46
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
A. Weber LBL Experiments 47
Neutrino Factory• Muon storage ring: The Ultimate Neutrino Source
A. Weber LBL Experiments 48
Neutrino Factory Physics
A. Weber LBL Experiments 49
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)