Recent Results from the MINOS Experiment Costas Andreopoulos (*) * - PowerPoint PPT Presentation

Recent Results from the MINOS Experiment Costas Andreopoulos (*) * for the MINOS collaboration Double Beta Decay & Neutrinos 2007 (DBD07), June 11-13, Osaka, Japan

Outline ● Introduction ● Neutrino Oscillations Outline ● Open Questions v Oscillations ● MINOS Physics Goals MINOS Goals MINOS Overview ● The MINOS Experiment Beamline ● How is it done? Detectors ● The NuMI beamline at Fermilab Events ● The Detectors ● Detector technology Event Id ● The FAR & NEAR detectors ND Spectra ● MINOS calibration Tuning ● Interaction types & Event topologies FD Prediction Observed spectrum ● The nu_mu CC disappearance analysis Allowed Regions ● Event selection Systematics ● NEAR Detector Energy Spectra Projected Sensitivity ● Hadron production tuning ● Predicting the FAR Detector Energy Spectrum Summary ● Observed Rates & Best fit spectrum ● Allowed Regions & Best fit parameters ● Systematics ● Projected Sensitivity ● Summary Costas Andreopoulos

Neutrino Oscillations A quantum-mechanical interference effect Outline Production & Detection: Governed by electoweak hamiltonian v Oscillations Producing / detecting interaction eigenstates (superposition of mass eigenstates ) MINOS Goals MINOS Overview Beamline Detectors Events lj li Event Id PMNS (CKM-like) unitary matrix ND Spectra vj vi Tuning W FD Prediction W Observed spectrum Allowed Regions Propagation: Governed by free hamiltonian Systematics Projected Sensitivity q bar{q} q bar{q} Each mass eigenstate propagates at different pace ! Relative mixture of mass eigenstates changes! Summary Flavour oscillations are possible Phenomenon has been observed with: solar , atmospheric , reactor & accelerator neutrinos! Costas Andreopoulos

Open Questions Goals: ● Determine the elements of the PMNS matrix Outline ● Determine neutrino mass (splittings) v Oscillations ● Impressive progress over the past decade - A 'precision measurement' era for neutrinos MINOS Goals ● Still many open questions : MINOS Overview Beamline Is theta23 maximal? Is CP violated at the How close to 0 is theta13? Detectors (hidden symmetry?) leptonic sector? (hidden symmetry?) Events Event Id ND Spectra Tuning improve FD Prediction precision Observed spectrum Allowed Regions Dirac/Majorana? MINOS/ (not accessible Systematics with oscillations) Projected Sensitivity Summary Can we measure the Which one? … or none (quasi-degenerate)? absolute scale? (not accessible with oscillations) Costas Andreopoulos

Physics Goals for MINOS MINOS: A precision oscillation experiment Outline v Oscillations MINOS Goals ● Test the v μ → τ oscillation hypothesis v MINOS Overview – Measure precisely | Δ m 2 32 | and sin 2 2 θ Beamline 23 Detectors Events ● Search for sub-dominant ν μ → ν e oscillations Event Id ND Spectra ● Search for/constrain exotic phenomena Tuning FD Prediction Observed spectrum ● Compare ν μ , ν μ oscillations Allowed Regions Systematics Projected Sensitivity ● Atmospheric neutrino oscillations Summary Phys. Rev. D73, 072002 (2006) – Costas Andreopoulos

How the experiment is done A 2 detector, long-baseline neutrino experiment using an intense, accelerator-made beam Soudan mine beam source Outline (nu_mu) is here Far v Oscillations Detector MINOS Goals MINOS Overview Beamline Detectors Events Near Detector Event Id ND Spectra Tuning FD Prediction Observed spectrum Allowed Regions Fermilab FarDet Systematics ~ 5.4 kton Projected Sensitivity Summary NearDet ~1 kton measures “oscillated” flux measures “un-oscillated” flux Costas Andreopoulos

Why a 2 detector experiment? Reducing systematic errors Outline – Effect of large flux & cross-section uncertainties minimized v Oscillations – Detector / reconstruction effects minimized MINOS Goals – 'Unoscillated' FAR spectrum extrapolated from NEAR MINOS Overview Beamline Detectors Events Monte Carlo Muon neutrino spectrum ratio Event Id ND Spectra Tuning Measures mixing strength Unoscillated FD Prediction Observed spectrum Allowed Regions Oscillated Systematics Projected Sensitivity Summary Measures squared mass splitting Costas Andreopoulos

Cross Section Uncertainty Why a 2 detector experiment? Reducing systematic errors Outline v Oscillations MINOS Goals MINOS Overview Beamline Detectors Events Event Id ND Spectra Tuning FD Prediction Observed spectrum Allowed Regions Systematics Projected Sensitivity Summary Costas Andreopoulos

Hadron Production Uncertainty Why a 2 detector experiment? Reducing systematic errors Outline v Oscillations MINOS Goals MINOS Overview Beamline Detectors Events Event Id ND Spectra Tuning FD Prediction Observed spectrum Allowed Regions Systematics Projected Sensitivity Summary Costas Andreopoulos

The MINOS Collaboration Brazil Outline MINOS Near Detector Campinas – Sao Paulo v Oscillations surface building France MINOS Goals MINOS Overview College de France Beamline Detectors Greece Events Athens Event Id Russia ND Spectra Tuning ITEP Moscow – Lebedev – FD Prediction Protvino Observed spectrum v Allowed Regions ' UK s t o w a Systematics r d s S Fermilab Cambridge – Oxford – RAL – o Projected Sensitivity u d a n Sussex - UCL Summary USA ● 6 countries Argonne – Benedictine – Brookhaven – Caltech – Fermilab – Harvard – IIT – ● 32 institutions Indiana – Livermore – Minnesota, Twin Cities – Minnesota, Duluth – Pittsburgh – ● ~175 physicists South Carolina – Stanford – Texas A&M – Texas-Austin – Tufts – Western Washington – William & Mary - Wisconsin Costas Andreopoulos

The NuMI beamline @ Fermilab a 'conventional' neutrino beam Outline v Oscillations MINOS Goals MINOS Overview Beamline Detectors First year averages: Events ● Intensity: 2.3E+13 POT/spill ● Cycle: 2.2 s ● Power: 170 kW Event Id ND Spectra ~pure / intense muon neutrino beam tunable energy Tuning FD Prediction Observed spectrum Allowed Regions Oscillation Systematics minimum for Projected Sensitivity Dm2=0.0025 eV^2 Summary Costas Andreopoulos

Detector Technology Massive segmented iron calorimeters, with inexpensively produced plastic scintillator as active material. The scintillation light is collected by WLS fibers read out by multianode PMTs. Outline v Oscillations steel planes ● 2.54 cm thick MINOS Goals MINOS Overview (4m) WLS Beamline emission Detectors spectrum Events Event Id ND Spectra typical Tuning PMT FD Prediction quantum WLS fibers Observed spectrum fiber efficiency Allowed Regions “ cookie” Systematics scintillator strips Projected Sensitivity ● 4.1 cm wide ● 1.0 cm thick Summary scintillator plane PMT dark box multianode PMT readout cable Costas Andreopoulos

The FAR Detector @ Soudan mine Purpose: nu mu CC, NC -- energy spectra & rates ● Measure _ Outline nu e appearance ● Search for _ v Oscillations ● Atmospheric Neutrino physics studies (upgoing muons, contained neutrino events,...) ● Cosmic Ray physics studies (mu+/mu- charge ratio, point sources, ...) MINOS Goals MINOS Overview Beamline cosmic muon veto shield Detectors ● at Soudan mine, MN (~1 Hz @ full detector) Events ● ~ 735 km from NuMI target ● depth: ~ 750 m Event Id ● ~ 5.4 kton ND Spectra ● 486 steel planes Tuning optical ● B ~ 1.3 T FD Prediction readout Observed spectrum 8 m ● 2-ended readout Allowed Regions ● 16-anode PMTs (HPK M16) Systematics steel plane ● x8 optical multiplexing (magnetized) Projected Sensitivity ● VA electronics Summary v beam coil B Field operational since June 2003 Costas Andreopoulos

The NEAR Detector @ Fermilab Purpose: ● Measure beam with high statistics before oscillations Outline ● Tune neutrino & beam / hadron-production MC v Oscillations ● Predict Far detector spectrum MINOS Goals MINOS Overview Beamline PMTs & front-end electronics Detectors ● at Fermilab Events ● ~ 1 km from NuMI target scintillator plane ● swallow depth: ~ 100 m Event Id ● ~ 1 kton ND Spectra 3.8 m ● 282 steel planes Tuning ● B Field ~ 1.2 T FD Prediction Observed spectrum v beam ● 1-ended readout Allowed Regions steel plane ● 64-anode PMTs (HPK M64) Systematics (magnetized) ● no multiplexing upstream Projected Sensitivity ● 4x MUX in spectrometer coil ● Very high rates Summary hole ● QIE electronics (no deadtime during spill) B Field operational since ~ November 2004 Costas Andreopoulos

MINOS Calibration Single particle energy resolution • Calibration detector • Determine overall energy scale Outline • Light Injection system v Oscillations • Determine/monitor PMT gains MINOS Goals • Cosmic ray muons 55 % / E MINOS Overview • Equalize strip to strip response Beamline • Equalize detector to detector response Detectors 23 % / E Events Event Id ND Spectra Tuning FD Prediction Observed spectrum Allowed Regions Systematics Energy scale calibration: Projected Sensitivity – 1.9% absolute error in ND – 3.5% absolute error in FD Summary – 3% relative Costas Andreopoulos