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

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

MINOS

New Results from MINOSPatricia Vahle, for the MINOS collaborationCollege of William and Mary

1The MINOS ExperimentP. Vahle, Neutrino 20102

Long base-line neutrino oscillation experimentNeutrinos from NuMI beam lineL/E ~ 500 km/GeVatmospheric m2

Two detectors mitigate systematic effectsbeam flux mis- modelingneutrino interaction uncertaintiesFar Detector735 km from SourceNear Detector1 km from Source2MINOS Physics GoalsP. Vahle, Neutrino 20103

Measure disappearance as a function of energy m232 and sin2(223) test oscillations vs. decay/decoherencem232m221

MINOS Physics GoalsP. Vahle, Neutrino 20104

Measure disappearance as a function of energy m232 and sin2(223) test oscillations vs. decay/decoherenceMixing to sterile neutrinos?m232m221

m214MINOS Physics GoalsP. Vahle, Neutrino 20105

m232m221Measure disappearance as a function of energy m232 and sin2(223) test oscillations vs. decay/decoherenceMixing to sterile neutrinos?Study e mixingmeasure 13

MINOS Physics GoalsP. Vahle, Neutrino 20106

Measure disappearance as a function of energy m232 and sin2(223) look for differences between neutrino and anti-neutrinosm232m221

MINOS Physics GoalsP. Vahle, Neutrino 20107

Measure disappearance as a function of energy m232 and sin2(223) look for differences between neutrino and anti-neutrinosMore MINOS analyses:atmospheric neutrinos (See A. Blake poster)cross section measurementsLorentz invariance testscosmic rays

m232m221

The DetectorsP. Vahle, Neutrino 20108

1 kt Near Detectormeasure beambefore oscillations

5.4 kt Far Detectorlook for changes in the beam relative to the Near DetectorMagnetized, tracking calorimeters735 km from source1 km from sourceDetector TechnologyP. Vahle, Neutrino 20109

Multi-anode PMTExtrudedPS scint.4.1 x 1 cm2WLS fiberClearFiber cables2.54 cm FeU V planes+/- 450

Tracking sampling calorimeterssteel absorber 2.54 cm thick (1.4 X0)scintillator strips 4.1 cm wide (1.1 Moliere radii)1 GeV muons penetrate 28 layersMagnetizedmuon energy from range/curvaturedistinguish + from -Functionally equivalentsame segmentation same materialssame mean B field (1.3 T)Making a neutrino beamP. Vahle, Neutrino 201010

Making a neutrino beamP. Vahle, Neutrino 201011Productionbombard graphite target with 120 GeV p+ from Main Injector2 interaction lengths310 kW typical powerproduce hadrons, mostly and K

Making a neutrino beamP. Vahle, Neutrino 201012Focusinghadrons focused by 2 magnetic focusing hornssign selected hadronsforward current, (+) for standard neutrino beam runsreverse current, () for anti-neutrino beam

Making a neutrino beamP. Vahle, Neutrino 201013Decay2 m diameter decay piperesult: wide band beam, peak determined by target/horn separationsecondary beam monitored (see L. Loiacono poster)

Beam PerformanceP. Vahle, Neutrino 201014

Protons per week (x1018)Total Protons (x1020)DateBeam PerformanceP. Vahle, Neutrino 201015

1021 POT!Protons per week (x1018)Total Protons (x1020)DateBeam PerformanceP. Vahle, Neutrino 201016

Previously published analysesProtons per week (x1018)Total Protons (x1020)DateBeam PerformanceP. Vahle, Neutrino 201017

Data set for todays reportAnti-neutrino runningHigh energy runningProtons per week (x1018)Total Protons (x1020)Date

e-CC e Event Events in MINOS

NC Event P. Vahle, Neutrino 201018 Charged Current events:long track, with hadronic activity at vertexneutrino energy from sum of muon energy (range or curvature) and shower energy

CC Event -Depth (m)Transverse position (m)

Simulated Events

e-CC e Event Events in MINOS

NC Event P. Vahle, Neutrino 201019

CC Event -Depth (m)

Transverse position (m)Neutral Current events:short, diffuse shower eventshower energy from calorimetric response

Simulated Events

e-CC e Event Events in MINOS

NC Event P. Vahle, Neutrino 201020

CC Event -Depth (m)

Transverse position (m)e Charged Current events:compact shower event with an EM coreneutrino energy from calorimetric responseSimulated EventsNear to FarP. Vahle, Neutrino 201021Neutrino energy depends on angle wrt original pion direction and parent energyhigher energy pions decay further along decay pipeangular distributions different between Near and Far

FDDecay Pipe+TargetNDpFar spectrum without oscillations is similar, but not identical to the Near spectrum!

ExtrapolationP. Vahle, Neutrino 201022Muon-neutrino and anti-neutrino analyses: beam matrix for FD prediction of track eventsNC and electron-neutrino analyses: Far to Near spectrum ratio for FD prediction of shower events

UnoscillatedOscillated spectrum DisappearanceP. Vahle, Neutrino 201023

spectrum ratioMonte Carlo(Input parameters: sin22 = 1.0, m2 = 3.35x10-3 eV2 )Characteristic ShapeMonte Carlo

UnoscillatedOscillated spectrum DisappearanceP. Vahle, Neutrino 201024

spectrum ratioMonte Carlo(Input parameters: sin22 = 1.0, m2 = 3.35x10-3 eV2 )Monte Carlosin2(2)

UnoscillatedOscillated spectrum DisappearanceP. Vahle, Neutrino 201025

spectrum ratioMonte Carlo(Input parameters: sin22 = 1.0, m2 = 3.35x10-3 eV2 )Monte Carlom2CC events in the Near DetectorP. Vahle, Neutrino 201026Show ND energy spectrum

Majority of data from low energy beamHigh energy beam improves statistics in energy range above oscillation dipAdditional exposure in other configurations for commissioning and systematics studiesAnalysis ImprovementsP. Vahle, Neutrino 201027

Since PRL 101:131802, 2008Additional data3.4x1020 7.2x1020 POTAnalysis improvementsupdated reconstruction and simulationnew selection with increased efficiencyno charge sign cutimproved shower energy resolutionseparate fits in bins of energy resolutionsmaller systematic uncertaintiesSee C. Backhouse, J. Mitchell, and J. Ratchford, M. Strait posters

Far Detector Energy SpectrumP. Vahle, Neutrino 201028

No Oscillations:2451Observation:1986Far Detector Energy SpectrumP. Vahle, Neutrino 201029

Oscillations fit the data well, 66% of experiments have worse 2Pure decoherence disfavored:> 8Pure decay disfavored: > 6(7.8 if NC events included)G.L. Fogli et al., PRD 67:093006 (2003) V. Barger et al.,PRL 82:2640 (1999)

ContoursP. Vahle, Neutrino 201030Contour includes effects of dominant systematic uncertaintiesnormalizationNC backgroundshower energytrack energy

ContoursP. Vahle, Neutrino 201031Contour includes effects of dominant systematic uncertaintiesnormalizationNC backgroundshower energytrack energy

Super-Kamiokande Collaboration (preliminary)

Neutral Current Near Event RatesP. Vahle, Neutrino 201032

Neutral Current event rate should not change in standard 3 flavor oscillationsA deficit in the Far event rate could indicate mixing to sterile neutrinose CC events would be included in NC sample, results depend on the possibility of e appearance

See P. Rodrigues and A. Sousa poster

Neutral Currents in the Far DetectorP. Vahle, Neutrino 201033Expect: 757 eventsObserve: 802 eventsNo deficit of NC events

no (with) e appearance

e AppearanceP. Vahle, Neutrino 201034

A few percent of the missing could change into e depending on value of 13Appearance probability additionally depends on CP and mass hierarchy

Normal Hierarchy

Inverted Hierarchy?Looking for electron-neutrinosP. Vahle, Neutrino 20103511 shape variables in a Neural Net (ANN)characterize longitudinal and transverse energy depositionApply selection to ND data to predict background level in FDNC, CC, beam e each extrapolates differentlytake advantage of NuMI flexibility to separate background components

e selected region Data MCBG RegionSee R. Toner, L. Whitehead, G. Pawloski postere Appearance ResultsP. Vahle, Neutrino 201036Based on ND data, expect: 49.17.0(stat.)2.7(syst.)

e Appearance ResultsP. Vahle, Neutrino 201037Based on ND data, expect: 49.17.0(stat.)2.7(syst.)Observe:54 events in the FD, a 0.7 excess

e Appearance ResultsP. Vahle, Neutrino 201038

arXiv:1006.0996v1 [hep-ex]

Making an anti-neutrino beamP. Vahle, Neutrino 201039

-+TargetFocusing Horns2 m675 m15 m30 m120 GeV ps from MINeutrino modeHorns focus +, K+:91.7% :7.0%e+e :1.3%Events

Making an anti-neutrino beamP. Vahle, Neutrino 201040

-+TargetFocusing Horns2 m675 m15 m30 m120 GeV ps from MIAnti-neutrino ModeHorns focus -, K- enhancing the fluxNeutrino modeHorns focus +, K+:39.9% :58.1%e+e :2.0%EventsEvents:91.7% :7.0%e+e :1.3%ND Anti-neutrino DataP. Vahle, Neutrino 201041Focus and select positive muonspurity 94.3% after charge sign cutpurity 98% < 6GeVAnalysis proceeds as (2008) neutrino analysisData/MC agreement comparable to neutrino runningdifferent average kinematic distributionsmore forward muons

See J. Evans, N. Devenish posterAlso A. Blake poster on atmospheric neutrinosND DataP. Vahle, Neutrino 201042

Data/MC agreement comparable to neutrino running

FD DataP. Vahle, Neutrino 201043

No oscillation Prediction: 155Observe: 97No oscillations disfavored at 6.3

FD DataP. Vahle, Neutrino 201044

No oscillation Prediction: 155Observe: 97No oscillations disfavored at 6.3

FD DataP. Vahle, Neutrino 201045

Comparisons to NeutrinosP. Vahle, Neutrino 201046

Comparisons to NeutrinosP. Vahle, Neutrino 201047SummaryP. Vahle, Neutrino 201048With 7x1020 POT of neutrino beam, MINOS findsmuon-neutrinos disappear

NC event rate is not diminished

electron-neutrino appearance is limited

With 1.71x1020 POT of anti-neutrino beammuon anti-neutrinos also disappear with

we look forward to more anti-neutrino beam!

Backup SlidesP. Vahle, Neutrino 201049

LE 10MEHENeutrino SpectrumP. Vahle, Neutrino 201050Use flexibility of beam line to constrain hadron production, reduce uncertainties due to neutrino fluxNear to FarP. Vahle, Neutrino 201051Far spectrum without oscillations is similar, but not identical to the Near spectrum!

Far/Near differencesP. Vahle, Neutrino 201052 CC events oscillate awayEvent topologyLight level differences (differences in fiber lengths)Multiplexing in Far (8 fibers per PMT pixel)Single ended readout in NearPMTs (M64 in Near Detector, M16 in Far):Different gains/front end electronicsDifferent crosstalk patternsNeutrino intensityRelative energy calibration/energy resolution

Account for these lower order effects using detailed detector simulationNew Muon-neutrino CC SelectionP. Vahle, Neutrino 201053

Shower Energy ResolutionP. Vahle, Neutrino 201054Energy Resolution BinningP. Vahle, Neutrino 201055

CC Systematic UncertaintiesP. Vahle, Neutrino 201056

Dominant systematic uncertainties:hadronic energy calibrationtrack energy calibrationNC backgroundrelative Near to Far normalization

Resolution BinningP. Vahle, Neutrino 201057Contours by Run PeriodP. Vahle, Neutrino 201058

Rock and Anti-fiducial EventsP. Vahle, Neutrino 201059Neutrinos interact in rock around detector and outside of Fiducial RegionThese events double sample size, events have poorer energy resolution

Combined fit coming soonFits to NCP. Vahle, Neutrino 201060Fit CC/NC spectra simultaneously with a 4th (sterile) neutrino2 choices for 4th mass eigenvaluem4>>m3m4=m1

Electron-neutrino Background DecompositionP. Vahle, Neutrino 201061

Electron-neutrino SystematicsP. Vahle, Neutrino 201062

Stats. Err.MRCC Background Rejection CheckP. Vahle, Neutrino 201063R

Neutrino Energy: 5.3 GeVMuon Energy: 3.2 GeV

Remnant Energy: 2.1 GeVANN PID: 0.86

Mis-id rate:pred (6.420.05)%data (7.20.9)%(stats error only)Compatible at 0.86Remove muons, test BG rejection on shower remnants

Checking Signal EfficiencyP. Vahle, Neutrino 201064Test beam measurements demonstrate electrons are well simulatedChecking Signal EfficiencyP. Vahle, Neutrino 201065Check electron neutrino selection efficiency by removing muons, add a simulated electron

P. Vahle, Neutrino 201066Hadron production and cross sections conspire to change the shape and normalization of energy spectrum

~3x fewer antineutrinos for the same exposureMaking an antineutrino beam

Anti-neutrino SelectionP. Vahle, Neutrino 201067- Not FocusedCoil Hole+ FocusedCoil HoleAnti-neutrino SystematicsP. Vahle, Neutrino 201068

FD Anti-neutrino DataP. Vahle, Neutrino 201069

Vertices uniformly distributedTrack ends clustered around coil holePrevious Anti-neutrino ResultsP. Vahle, Neutrino 201070

Results consistent with (less sensitive) analysis of anti-neutrinos in the neutrino beamanti-neutrinos from unfocused beam componentmostly high energy antineutrinosAnalysis of larger exposure on going

Future Anti-neutrino SensitivityP. Vahle, Neutrino 201071

Atmospheric NeutrinosP. Vahle, Neutrino 201072

Near Detector Neutrino Energy (GeV)0 5 10 15 20 25 30

Far D

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tor N

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no E

nerg

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5

10

15

20

25

30

-1010

-910

-810

-710

-610

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MINOS best fit

MINOS 90%

MINOS 68%

MINOS 2008 90%

MINOS 2006 90%

POT - fiducial events20107.2

MINOS Preliminary

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-0.10

-0.05

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Overall hadronic energyTrack energyNC backgroundRelative normalisationRelative hadronic energyCross sectionsCharge mis-IDBeam

MINOS PRELIMINARYFar Detector MC

Fiducial events POT20 107.2

z position (m)16 17 18 19 20 21 22

tran

svers

e p

osit

ion

(m

)

-3.2

-3

-2.8

-2.6

-2.4

-2.2

-2

-1.8

-1.6

-1.4

Transverse vs Z view - U Planes

z position (m)19 20 21 22 23 24

tran

svers

e p

osit

ion

(m

)

-4

-3.5

-3

-2.5

-2

Transverse vs Z view - U Planes