NEW RESULTS FROM MINOS Patricia Vahle, for the MINOS collaboration College of William and Mary

The MINOS Experiment P. Vahle, Neutrino  Long base-line neutrino oscillation experiment  Neutrinos from NuMI beam line  L/E ~ 500 km/GeV  atmospheric Δm 2  Two detectors mitigate systematic effects  beam flux mis- modeling  neutrino interaction uncertainties Far Detector 735 km from Source Near Detector 1 km from Source

MINOS Physics Goals P. Vahle, Neutrino  Measure ν μ disappearance as a function of energy  Δm 2 32 and sin 2 (2θ 23 )  test oscillations vs. decay/decoherence Δm 2 32 Δm 2 21

MINOS Physics Goals P. Vahle, Neutrino  Measure ν μ disappearance as a function of energy  Δm 2 32 and sin 2 (2θ 23 )  test oscillations vs. decay/decoherence  Mixing to sterile neutrinos? Δm 2 32 Δm 2 21 Δm 2 14

MINOS Physics Goals P. Vahle, Neutrino Δm 2 32 Δm 2 21  Measure ν μ disappearance as a function of energy  Δm 2 32 and sin 2 (2θ 23 )  test oscillations vs. decay/decoherence  Mixing to sterile neutrinos?  Study ν μ →ν e mixing  measure θ 13

MINOS Physics Goals P. Vahle, Neutrino  Measure ν μ disappearance as a function of energy  Δm 2 32 and sin 2 (2θ 23 )  look for differences between neutrino and anti-neutrinos Δm 2 32 Δm 2 21

MINOS Physics Goals P. Vahle, Neutrino  Measure ν μ disappearance as a function of energy  Δm 2 32 and sin 2 (2θ 23 )  look for differences between neutrino and anti-neutrinos  More MINOS analyses:  atmospheric neutrinos (See A. Blake poster)  cross section measurements  Lorentz invariance tests  cosmic rays Δm 2 32 Δm 2 21

The Detectors P. Vahle, Neutrino kt Near Detector— measure beam before oscillations 5.4 kt Far Detector— look for changes in the beam relative to the Near Detector Magnetized, tracking calorimeters 735 km from source 1 km from source

Detector Technology P. Vahle, Neutrino Multi-anode PMT Extruded PS scint. 4.1 x 1 cm 2 Extruded PS scint. 4.1 x 1 cm 2 WLS fiber Clear Fiber cables Clear Fiber cables 2.54 cm Fe U V planes +/ U V planes +/  Tracking sampling calorimeters  steel absorber 2.54 cm thick (1.4 X 0 )  scintillator strips 4.1 cm wide (1.1 Moliere radii)  1 GeV muons penetrate 28 layers  Magnetized  muon energy from range/curvature  distinguish μ + from μ -  Functionally equivalent  same segmentation  same materials  same mean B field (1.3 T)

Making a neutrino beam P. Vahle, Neutrino

Making a neutrino beam P. Vahle, Neutrino  Production  bombard graphite target with 120 GeV p + from Main Injector 2 interaction lengths 310 kW typical power  produce hadrons, mostly π and K

Making a neutrino beam P. Vahle, Neutrino  Focusing  hadrons focused by 2 magnetic focusing horns  sign selected hadrons forward current, (+) for standard neutrino beam runs reverse current, (–) for anti-neutrino beam

Making a neutrino beam P. Vahle, Neutrino  Decay  2 m diameter decay pipe  result: wide band beam, peak determined by target/horn separation  secondary beam monitored (see L. Loiacono poster)

Beam Performance P. Vahle, Neutrino Protons per week (x10 18 ) Total Protons (x10 20 ) Date

Beam Performance P. Vahle, Neutrino POT! Protons per week (x10 18 ) Total Protons (x10 20 ) Date

Beam Performance P. Vahle, Neutrino Previously published analyses Protons per week (x10 18 ) Total Protons (x10 20 ) Date

Beam Performance P. Vahle, Neutrino Data set for today’s report Anti- neutrino running High energy running Protons per week (x10 18 ) Total Protons (x10 20 ) Date

e-e- CC ν e Event Events in MINOS NC Event ν P. Vahle, Neutrino  ν μ Charged Current events:  long μ track, with hadronic activity at vertex  neutrino energy from sum of muon energy (range or curvature) and shower energy CC ν μ Event μ-μ- Depth (m) Transverse position (m) Simulated Events

e-e- CC ν e Event Events in MINOS NC Event ν P. Vahle, Neutrino CC ν μ Event μ-μ- Depth (m) Transverse position (m)  Neutral Current events:  short, diffuse shower event  shower energy from calorimetric response Simulated Events

e-e- CC ν e Event Events in MINOS NC Event ν P. Vahle, Neutrino CC ν μ Event μ-μ- Depth (m) Transverse position (m)  ν e Charged Current events:  compact shower event with an EM core  neutrino energy from calorimetric response Simulated Events

Near to Far P. Vahle, Neutrino  Neutrino energy depends on angle wrt original pion direction and parent energy  higher energy pions decay further along decay pipe  angular distributions different between Near and Far FD Decay Pipe π+π+ Target ND p Far spectrum without oscillations is similar, but not identical to the Near spectrum!

Extrapolation P. Vahle, Neutrino  Muon-neutrino and anti-neutrino analyses: beam matrix for FD prediction of track events  NC and electron-neutrino analyses: Far to Near spectrum ratio for FD prediction of shower events

Unoscillated Oscillated ν μ spectrum ν μ Disappearance P. Vahle, Neutrino spectrum ratio Monte Carlo (Input parameters: sin 2 2θ = 1.0, Δm 2 = 3.35x10 -3 eV 2 ) Characteristic Shape Monte Carlo

Unoscillated Oscillated ν μ spectrum ν μ Disappearance P. Vahle, Neutrino spectrum ratio Monte Carlo (Input parameters: sin 2 2θ = 1.0, Δm 2 = 3.35x10 -3 eV 2 ) Monte Carlo sin 2 (2θ)

Unoscillated Oscillated ν μ spectrum ν μ Disappearance P. Vahle, Neutrino spectrum ratio Monte Carlo (Input parameters: sin 2 2θ = 1.0, Δm 2 = 3.35x10 -3 eV 2 ) Monte Carlo Δm2Δm2

CC events in the Near Detector P. Vahle, Neutrino  Show ND energy spectrum  Majority of data from low energy beam  High energy beam improves statistics in energy range above oscillation dip  Additional exposure in other configurations for commissioning and systematics studies

Analysis Improvements P. Vahle, Neutrino  Since PRL 101:131802, 2008  Additional data  3.4x10 20 → 7.2x10 20 POT  Analysis improvements  updated reconstruction and simulation  new selection with increased efficiency  no charge sign cut  improved shower energy resolution  separate fits in bins of energy resolution  smaller systematic uncertainties See C. Backhouse, J. Mitchell, and J. Ratchford, M. Strait posters

Far Detector Energy Spectrum P. Vahle, Neutrino No Oscillations: 2451 Observation:1986

Far Detector Energy Spectrum P. Vahle, Neutrino  Oscillations fit the data well, 66% of experiments have worse χ 2  Pure decoherence † disfavored:> 8 σ  Pure decay ‡ disfavored: > 6 σ (7.8σ if NC events included) † G.L. Fogli et al., PRD 67: (2003) ‡ V. Barger et al.,PRL 82:2640 (1999)

Contours P. Vahle, Neutrino  Contour includes effects of dominant systematic uncertainties  normalization  NC background  shower energy  track energy

Contours P. Vahle, Neutrino  Contour includes effects of dominant systematic uncertainties  normalization  NC background  shower energy  track energy †Super-Kamiokande Collaboration (preliminary) †

Neutral Current Near Event Rates P. Vahle, Neutrino  Neutral Current event rate should not change in standard 3 flavor oscillations  A deficit in the Far event rate could indicate mixing to sterile neutrinos  ν e CC events would be included in NC sample, results depend on the possibility of ν e appearance See P. Rodrigues and A. Sousa poster

Neutral Currents in the Far Detector P. Vahle, Neutrino  Expect: 757 events  Observe: 802 events  No deficit of NC events no (with) ν e appearance

ν e Appearance P. Vahle, Neutrino  A few percent of the missing ν μ could change into ν e depending on value of θ 13  Appearance probability additionally depends on δ CP and mass hierarchy Normal Hierarchy Inverted Hierarchy ?⇔?⇔

Looking for electron-neutrinos P. Vahle, Neutrino  11 shape variables in a Neural Net (ANN)  characterize longitudinal and transverse energy deposition  Apply selection to ND data to predict background level in FD  NC, CC, beam ν e each extrapolates differently  take advantage of NuMI flexibility to separate background components ν e selected region Data  MC BG Region See R. Toner, L. Whitehead, G. Pawloski poster

ν e Appearance Results P. Vahle, Neutrino  Based on ND data, expect: 49.1±7.0(stat.)±2.7(syst.)

ν e Appearance Results P. Vahle, Neutrino  Based on ND data, expect: 49.1±7.0(stat.)±2.7(syst.)  Observe:54 events in the FD, a 0.7 σ excess

ν e Appearance Results P. Vahle, Neutrino arXiv: v1 [hep-ex]

Making an anti-neutrino beam P. Vahle, Neutrino π-π- π+π+ Target Focusing Horns 2 m 675 m νμνμ νμνμ 15 m 30 m 120 GeV p’s from MI Neutrino mode Horns focus π +, K + ν μ :91.7% ν μ :7.0% ν e + ν e :1.3% Events

Making an anti-neutrino beam P. Vahle, Neutrino π-π- π+π+ Target Focusing Horns 2 m 675 m νμνμ νμνμ 15 m 30 m 120 GeV p’s from MI Anti-neutrino Mode Horns focus π -, K - enhancing the ν μ flux Neutrino mode Horns focus π +, K + ν μ :39.9% ν μ :58.1% ν e + ν e :2.0% Events ν μ :91.7% ν μ :7.0% ν e + ν e :1.3%

ND Anti-neutrino Data P. Vahle, Neutrino  Focus and select positive muons  purity 94.3% after charge sign cut  purity 98% < 6GeV  Analysis proceeds as (2008) neutrino analysis  Data/MC agreement comparable to neutrino running  different average kinematic distributions  more forward muons See J. Evans, N. Devenish poster Also A. Blake poster on atmospheric neutrinos

ND Data P. Vahle, Neutrino  Data/MC agreement comparable to neutrino running

FD Data P. Vahle, Neutrino  No oscillation Prediction: 155  Observe: 97  No oscillations disfavored at 6.3 σ

FD Data P. Vahle, Neutrino  No oscillation Prediction: 155  Observe: 97  No oscillations disfavored at 6.3 σ

FD Data P. Vahle, Neutrino

Comparisons to Neutrinos P. Vahle, Neutrino

Comparisons to Neutrinos P. Vahle, Neutrino

Summary P. Vahle, Neutrino  With 7x10 20 POT of neutrino beam, MINOS finds  muon-neutrinos disappear  NC event rate is not diminished  electron-neutrino appearance is limited  With 1.71x10 20 POT of anti- neutrino beam  muon anti-neutrinos also disappear with  we look forward to more anti- neutrino beam!

Backup Slides P. Vahle, Neutrino

LE 10 ME HE Neutrino Spectrum P. Vahle, Neutrino  Use flexibility of beam line to constrain hadron production, reduce uncertainties due to neutrino flux

Near to Far P. Vahle, Neutrino Far spectrum without oscillations is similar, but not identical to the Near spectrum!

Far/Near differences P. Vahle, Neutrino  ν μ CC events oscillate away  Event topology  Light level differences (differences in fiber lengths)  Multiplexing in Far (8 fibers per PMT pixel)  Single ended readout in Near  PMTs (M64 in Near Detector, M16 in Far):  Different gains/front end electronics  Different crosstalk patterns  Neutrino intensity  Relative energy calibration/energy resolution Account for these lower order effects using detailed detector simulation

New Muon-neutrino CC Selection P. Vahle, Neutrino

Shower Energy Resolution P. Vahle, Neutrino

Energy Resolution Binning P. Vahle, Neutrino

CC Systematic Uncertainties P. Vahle, Neutrino  Dominant systematic uncertainties:  hadronic energy calibration  track energy calibration  NC background  relative Near to Far normalization

Resolution Binning P. Vahle, Neutrino

Contours by Run Period P. Vahle, Neutrino

Rock and Anti-fiducial Events P. Vahle, Neutrino  Neutrinos interact in rock around detector and outside of Fiducial Region  These events double sample size, events have poorer energy resolution Combined fit coming soon

Fits to NC P. Vahle, Neutrino  Fit CC/NC spectra simultaneously with a 4 th (sterile) neutrino  2 choices for 4 th mass eigenvalue  m 4 >>m 3  m 4 =m 1

Electron-neutrino Background Decomposition P. Vahle, Neutrino

Electron-neutrino Systematics P. Vahle, Neutrino Stats. Err.

MRCC Background Rejection Check P. Vahle, Neutrino R Neutrino Energy: 5.3 GeV Muon Energy: 3.2 GeV Remnant Energy: 2.1 GeV ANN PID: 0.86  Mis-id rate:  pred (6.42±0.05)%  data (7.2±0.9)% ( stats error only)  Compatible at 0.86 σ Remove muons, test BG rejection on shower remnants

Checking Signal Efficiency P. Vahle, Neutrino  Test beam measurements demonstrate electrons are well simulated

Checking Signal Efficiency P. Vahle, Neutrino  Check electron neutrino selection efficiency by removing muons, add a simulated electron

P. Vahle, Neutrino  Hadron production and cross sections conspire to change the shape and normalization of energy spectrum ~3x fewer antineutrinos for the same exposure Making an antineutrino beam

Anti-neutrino Selection P. Vahle, Neutrino μ - Not Focused Coil Hole μ + Focused Coil Hole

Anti-neutrino Systematics P. Vahle, Neutrino

FD Anti-neutrino Data P. Vahle, Neutrino  Vertices uniformly distributed  Track ends clustered around coil hole

Previous Anti-neutrino Results P. Vahle, Neutrino  Results consistent with (less sensitive) analysis of anti- neutrinos in the neutrino beam  anti-neutrinos from unfocused beam component  mostly high energy antineutrinos  Analysis of larger exposure on going

Future Anti-neutrino Sensitivity P. Vahle, Neutrino

Atmospheric Neutrinos P. Vahle, Neutrino