Long Baseline Neutrino Oscillation Experiments Alfons Weber RAL/University of Oxford RAL -Southampton Meeting RAL February 7, 2003

Contents Introduction Long baseline experiments The Future SNO KamLAND SuperKamiokande K2K MINOS OPERA ICARUS The Future Off-Axis Experiments Neutrino Factories A. Weber LBL Experiments

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

Neutrino Mixing Assume that neutrinos do have mass: mass eigenstates  weak interaction eigenstates Analogue to CKM-Matrix in quark sector! Mass eigenstates m1, m2, m3 weak “flavour eigenstates” Unitary mixing matrix: 3 mixing angles & 1 complex phase A. Weber LBL Experiments

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: A. Weber LBL Experiments

Oscillation Signature measures m2 No effect! Smeared by resolution P ~ 1/2 A. Weber LBL Experiments

The Solar Neutrino Problem Not enough electron neutrinos from the sun Different detectors (Super-K, Homestake, Gallex, Sage,…) Different detection thresholds All detectors observe neutrino neutrino deficit Reasons: magnetic moment neutrino oscillations Add solar neutrino spectrum A. Weber LBL Experiments

The SNO Experiment A. Weber LBL Experiments

Neutrino Reactions in SNO CC - e p d +  n p well measured ne energy spectrum weak angular dependence  1-1/3cos(q) ne only NC x n +  p d same cross section for all neutrinos measures total 8B n-flux of the sun ES - +  e n x few events mainly sensitive to ne, (less to n and n ) strong angular correlation A. Weber LBL Experiments

SNO Neutrino flux Fssm = 5.05 Fsno = 5.09 +1.01 -0.81 +0.44 -0.43 +0.46 -0.43 Fsno = 5.09 A. Weber LBL Experiments

combination of all experimental and solar model information Interpretation combination of all experimental and solar model information A. Weber LBL Experiments

KamLAND 1 kton LScint. detector in the Kamioka cavern H2O veto counter 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 710-6eV2 A. Weber LBL Experiments

KamLAND Collaboration 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.Wang IHEP, 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 Berkeley L.Hannelius, G.A.Horton-Smith, R.D.McKeown, J.Ritter, B.Tipton, P.Vogel California Institute of Technology C.E.Lane Drexel University J.Learned, J.Maricic, S.Matsuno, S.Pakvasa University of Hawaii S.Hatakeyama, R.C.Svoboda Louisiana State University B.D.Dieterle, C.Gregory University of New Mexico J.Detwiler, G.Gratta, H-L.Liew, D.Murphree, N.Tolich, Y. Uchida Stanford University Y.Kamyshkov, W.Bugg, Y.Efremenko, H.Cohn, A.Weidemann, S.Berridge, M.Schram, M.Batygov, Y.Nakamura University of Tennessee L.Braeckeleer, C.Gould, C.L.HoeM.Hornish, H.Karwowski, D.Markoff, J.Messimore, K.Nakamura, R.Rohm, N.Simmons, W.Tornow TUNL A. Weber LBL Experiments

Neutrino energy measured Detecting Neutrinos Large(r) cross-section Specific signature e+ kinetic energy (<8 MeV) 2 annihilation γs (0.5 MeV) neutron capture (2 to 8 MeV) ~2 events / day Neutrino energy measured from positron energy A. Weber LBL Experiments

So… what does an event look like ? KamLAND Event So… what does an event look like ? Charge: Red a lot, Blue little Time: Red soon, Blue late A. Weber LBL Experiments

KamLAND Results Measure rate and energy spectrum of reactor neutrinos Clear confirmation of LMA A. Weber LBL Experiments

Atmospheric Neutrinos Atmosphere is bombarded by cosmic rays Protons (H+) nuclei (He, Li, …) photons … some particles (1&2) produce hadronic shower Neutrino ratio A. Weber LBL Experiments

The SuperKamiokande Experiment H2O Cherenkov Detector Proton decay Neutrino interactions A. Weber LBL Experiments

SuperK Results Atmospheric neutrinos Muon neutrinos are missing! A. Weber LBL Experiments

Prototype of a Long-Baseline-Experiments The K2K Experiment Prototype of a Long-Baseline-Experiments Baseline: 250 km 1020 protons on target E = 12 GeV Neutrino energy: 1.4 GeV A. Weber LBL Experiments

K2K Results A. Weber LBL Experiments

The MINOS Experiment NuMI beam to Soudan in MN (distance 735 km) Sagitta:10 km >1 km wide at destination A. Weber LBL Experiments

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 12 ton 0.9 kton 5.4 kton A. Weber LBL Experiments

MINOS Far Detector 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 Photo by Jerry Meier MINOS cavern in blue A. Weber LBL Experiments

The MINOS Mural A. Weber LBL Experiments

Scintillator plane alternating orientations 90o in successive planes MINOS planes 2-m wide, 0.5-inch thick steel plates Upper steel layer Scintillator plane alternating orientations 90o in successive planes Lower steel layer A. Weber LBL Experiments

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

MINOS Oscillation Physics Several channels to analyse neutrino oscillations T-Test = #CC / #NC ne appearance (q13) Combination of all analysis will reveal mixing parameters Dm2 sin22q flavour hadrons nμ μ nm disappearance 5 m nt appearance hadrons n μ nμ 1.5 m A. Weber LBL Experiments

nμ CC Energy Analysis Select nμ charge current events and reconstruct neutrino energy Energy resolution: Compare energy spectrum in near and far detector Measure m2 and sin22 range, B field calorimetric m2 sin22 A. Weber LBL Experiments

μ Disappearance Results A. Weber LBL Experiments

First Neutrino Event Upward going Muon! Y t from below from above z A. Weber LBL Experiments

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

CERN Neutrinos to Grand Sasso CNGS Beam Baseline: 730km <E > = 17 GeV optimised for  neutrino appearance CERN Neutrinos to Grand Sasso Experiments ICARUS OPERA try find  by searching for decay kink nuclear emulsion CERN SPS Ep = 400 GeV 4.8*1013 ppp cycle 6 - 27.6 sec 7.6*1019 pot/year A. Weber LBL Experiments

The OPERA Experiment n m spectrometer n target and t decay detector Magnetised Iron Dipoles Drift tubes and RPCs ~ 10 m n super module brick (56 Pb/Em. “cells”) 8 cm (10X0) scintillator strips brick wall module n target and t decay detector Each “super-module” is a sequence of 24 “modules” consisting of - a “wall” of Pb/emulsion “bricks” - planes of orthogonal scintillator strips A. Weber LBL Experiments

Selected bricks extracted daily OPERA Target Section Sampling by Target Tracker planes ( X,Y ) Brick wall 10 cm Selected brick Event as seen by the target tracker 0 max p.h. Emulsion-Scintillator strip Hybrid Target Tracker task select bricks efficiently High scanning power + low background allow coarse tracking Selected bricks extracted daily using dedicated robot A. Weber LBL Experiments

OPERA Emulsion Brick n 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 n 10X0 ( 56 emulsion films ) 12.5cm 235k bricks for 3 super modules A. Weber LBL Experiments

OPERA  Candidates reconstruct kink topology “ Long decays reconstruct kink topology “ Short decays  detect large impact parameter track Loose cut to reject low momentum tracks A. Weber LBL Experiments

OPERA: m2 (mixing constrained by SuperK) OPERA 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 OPERA 90 % CL in 5 years (mixing constrained by SuperK) * assuming the observation of a number of events corresponding to those expected for the given m2 Probability to observe SuperK signal A. Weber LBL Experiments

Physics Technology Nucleon Decay Atmospheric Neutrinos Solar Neutrinos Beam Neutrinos (CNGS) Technology Liquid Argon TPC 3D tracking Scintillation light & PMTs trigger readout A. Weber LBL Experiments

Detail of a long (14 m) m track 2 Drift coord. (m) Full 2D View from the Collection Wire Plane 2 1 3 2 Wire coord. (m) 2 4 6 12 18 1 El.m. shower 2 Zoom views m stop and decay in e Detail of a long (14 m) m track with d-ray spots 3 El.m. shower T600 test @ Pv: Run 201 - Evt 12 A. Weber LBL Experiments

Sensitivity similar to OPERA! ICARUS Sensitivity atmospheric beam Sensitivity similar to OPERA! A. Weber LBL Experiments

Sub-dominant Oscillation Modes Main oscillation mode known solar: atmospheric: Measure sub-dominant oscillation mode P (nm  ne) = P1 + P2 + P3 + P4 A. Weber LBL Experiments

Measuring ne Oscillations Needs low ne beam contamination narrow band beam (suppresses NC contamination) NuMI Off-Axis Beam already there NC (visible energy), no rejection nm spectrum ne (|Ue32| = 0.01) ne background A. Weber LBL Experiments

Detector Options Detector on Surface Technologies (low Z) Requirements 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

J2K: JHF-SuperK New beam from JAERI Phase I Detector exists! Phase II 50 GeV, 0.77 MW 3.3*1014 ppp / 3.3 sec Phase I approved start operation 2007 Detector exists! Phase II Increase beam power: 4 MW HyperKamiokande: 1 Mton Possibility of measuring CP-violation, if parameters are right! No need for -factory? A. Weber LBL Experiments

SuperBeam Physics Sensitivity (phase I) CP violation (phase II)  μ disappearance (1 year) CP violation (phase II) A. Weber LBL Experiments

Neutrino Factory Muon storage ring: The Ultimate Neutrino Source A. Weber LBL Experiments

Neutrino Factory Physics A. Weber LBL Experiments

Summary Present Future Science fantasy 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) A. Weber LBL Experiments