New Results from MINOS

72
NEW RESULTS FROM MINOS Patricia Vahle, for the MINOS collaboration College of William and Mary

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New Results from MINOS. Patricia Vahle, for the MINOS collaboration College of William and Mary. The MINOS Experiment. Long base-line neutrino oscillation experiment Neutrinos from NuMI beam line L/E ~ 500 km/ GeV atmospheric Δm 2. Far Detector 735 km from Source. - PowerPoint PPT Presentation

Transcript of New Results from MINOS

Page 1: New Results from MINOS

NEW RESULTS FROM MINOS

Patricia Vahle, for the MINOS collaborationCollege of William and Mary

Page 2: New Results from MINOS

2The MINOS Experiment

P. Vahle, Neutrino 2010

Long base-line neutrino oscillation experiment

Neutrinos from NuMI beam lineL/E ~ 500

km/GeVatmospheric Δm2

Two detectors mitigate systematic effects

beam flux mis- modeling

neutrino interaction uncertainties

Far Detector735 km from Source

Near Detector1 km from

Source

Page 3: New Results from MINOS

3MINOS Physics Goals

P. Vahle, Neutrino 2010

Measure νμ disappearance as a function of energy Δm2

32 and sin2(2θ23)

test oscillations vs. decay/decoherence

Δm232

Δm221

νμ → νX

Page 4: New Results from MINOS

4MINOS Physics Goals

P. Vahle, Neutrino 2010

Measure νμ disappearance as a function of energy Δm2

32 and sin2(2θ23)

test oscillations vs. decay/decoherence

Mixing to sterile neutrinos?

Δm232

Δm221

νμ → νS

Δm214

Page 5: New Results from MINOS

5MINOS Physics Goals

P. Vahle, Neutrino 2010

Δm232

Δm221

Measure νμ disappearance as a function of energy Δm2

32 and sin2(2θ23)

test oscillations vs. decay/decoherence

Mixing to sterile neutrinos?

Study νμ→νe mixing measure θ13

νμ → νe

Page 6: New Results from MINOS

6MINOS Physics Goals

P. Vahle, Neutrino 2010

Measure νμ disappearance as a function of energy Δm2

32 and sin2(2θ23)

look for differences between neutrino and anti-neutrinos

Δm232

Δm221

νμ → νX

Page 7: New Results from MINOS

7MINOS Physics Goals

P. Vahle, Neutrino 2010

Measure νμ disappearance as a function of energy Δm2

32 and sin2(2θ23)

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

Δm232

Δm221

νμ → νX

Page 8: New Results from MINOS

8The Detectors

P. Vahle, Neutrino 2010

1 kt Near Detector—measure beambefore 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

Page 9: New Results from MINOS

9Detector Technology

P. Vahle, Neutrino 2010

Multi-anode PMT

ExtrudedPS scint.4.1 x 1 cm2

WLS fiber

ClearFiber cables

2.54 cm Fe

U V planes+/- 450

Tracking sampling calorimeters steel absorber 2.54 cm thick (1.4

X0) 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)

Page 10: New Results from MINOS

10Making a neutrino beam

P. Vahle, Neutrino 2010

Page 11: New Results from MINOS

11Making a neutrino beam

P. Vahle, Neutrino 2010

Production bombard graphite target with 120 GeV p+ from Main

Injector 2 interaction lengths 310 kW typical power

produce hadrons, mostly π and K

Page 12: New Results from MINOS

12Making a neutrino beam

P. Vahle, Neutrino 2010

Focusing hadrons focused by 2 magnetic focusing horns sign selected hadrons

forward current, (+) for standard neutrino beam runs

reverse current, (–) for anti-neutrino beam

Page 13: New Results from MINOS

13Making a neutrino beam

P. Vahle, Neutrino 2010

Decay 2 m diameter decay pipe result: wide band beam, peak determined by

target/horn separation secondary beam monitored (see L. Loiacono

poster)

Page 14: New Results from MINOS

14Beam Performance

P. Vahle, Neutrino 2010

Prot

ons

per

wee

k (x

1018

) Total Protons (x1020)

Date

Page 15: New Results from MINOS

15Beam Performance

P. Vahle, Neutrino 2010

1021 POT!

Prot

ons

per

wee

k (x

1018

) Total Protons (x1020)

Date

Page 16: New Results from MINOS

16Beam Performance

P. Vahle, Neutrino 2010

Previously published analyses

Prot

ons

per

wee

k (x

1018

) Total Protons (x1020)

Date

Page 17: New Results from MINOS

17Beam Performance

P. Vahle, Neutrino 2010

Data set for today’s report

Anti-neutrino running

High energy running

Prot

ons

per

wee

k (x

1018

) Total Protons (x1020)

Date

Page 18: New Results from MINOS

18

e-

CC νe Event

Events in MINOSNC Event

ν

P. Vahle, Neutrino 2010

νμ 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 νμ Event

μ-

Depth (m)

Tran

sver

se

posi

tion

(m

)

νμ + N → μ + X

Simulated Events

Page 19: New Results from MINOS

19

e-

CC νe Event

Events in MINOSNC Event

ν

P. Vahle, Neutrino 2010

CC νμ Event

μ-

Depth (m)ν

α+ N → ν α + X

Tran

sver

se

posi

tion

(m

)

Neutral Current events: short, diffuse shower event shower energy from calorimetric response

Simulated Events

Page 20: New Results from MINOS

20

e-

CC νe Event

Events in MINOSNC Event

ν

P. Vahle, Neutrino 2010

CC νμ Event

μ-

Depth (m)νe + N → e− + X

Tran

sver

se

posi

tion

(m

)

νe Charged Current events: compact shower event with an EM core neutrino energy from calorimetric response

Simulated Events

Page 21: New Results from MINOS

21Near to Far

P. Vahle, Neutrino 2010

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

FDDecay Pipe

π+Target

ND

p

Far spectrum without oscillations is similar, but not identical to the Near spectrum!

Eν ≈0.43Eπ

1+γ2θν2

Page 22: New Results from MINOS

22Extrapolation

P. Vahle, Neutrino 2010

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

Page 23: New Results from MINOS

23

Unoscillated

Oscillated

νμ spectrum

νμ Disappearance

P. Vahle, Neutrino 2010

P(νμ → νμ )=1−siν2 2θ( )siν2(1.27Δμ 2L/ E)

spectrum ratio

Monte Carlo(Input parameters: sin22θ = 1.0, Δm2 = 3.35x10-3 eV2 )

Characteristic Shape

Monte Carlo

Page 24: New Results from MINOS

24

Unoscillated

Oscillated

νμ spectrum

νμ Disappearance

P. Vahle, Neutrino 2010

P(νμ → νμ )=1−siν2 2θ( )siν2(1.27Δμ 2L/ E)

spectrum ratio

Monte Carlo(Input parameters: sin22θ = 1.0, Δm2 = 3.35x10-3 eV2 )

Monte Carlo

sin2(2θ)

Page 25: New Results from MINOS

25

Unoscillated

Oscillated

νμ spectrum

νμ Disappearance

P. Vahle, Neutrino 2010

P(νμ → νμ )=1−siν2 2θ( )siν2(1.27Δμ 2L/ E)

spectrum ratio

Monte Carlo(Input parameters: sin22θ = 1.0, Δm2 = 3.35x10-3 eV2 )

Monte Carlo

Δm2

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26

CC events in the Near Detector

P. Vahle, Neutrino 2010

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

Page 27: New Results from MINOS

27Analysis Improvements

P. Vahle, Neutrino 2010

Since PRL 101:131802, 2008 Additional data

3.4x1020 → 7.2x1020 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

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28

Far Detector Energy Spectrum

P. Vahle, Neutrino 2010

No Oscillations:

2451

Observation: 1986

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29

Far Detector Energy Spectrum

P. Vahle, Neutrino 2010

Oscillations fit the data well, 66% of experiments have worse χ2

Pure decoherence† disfavored: > 8σPure decay‡ disfavored: > 6σ

(7.8σ if NC events included)†G.L. Fogli et al., PRD 67:093006 (2003) ‡V. Barger et al.,PRL 82:2640 (1999)

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30Contours

P. Vahle, Neutrino 2010

Contour includes effects of dominant systematic uncertainties normalization NC background shower energy track energy

Δm2 = 2.35−0.08+0.11 ×10−3eV2

sin2 (2θ ) > 0.91 (90% C.L.)

Page 31: New Results from MINOS

31Contours

P. Vahle, Neutrino 2010

Contour includes effects of dominant systematic uncertainties normalization NC background shower energy track energy

Δm2 = 2.35−0.08+0.11 ×10−3eV2

sin2 (2θ ) > 0.91 (90% C.L.)

†Super-Kamiokande Collaboration (preliminary)

Page 32: New Results from MINOS

32

Neutral Current Near Event Rates

P. Vahle, Neutrino 2010

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

νe CC events would be included in NC sample, results depend on the possibility of νe appearanceSee P. Rodrigues

and A. Sousa poster

Page 33: New Results from MINOS

33

Neutral Currents in the Far Detector

P. Vahle, Neutrino 2010

Expect: 757 events Observe: 802 events No deficit of NC events

fs ≡Pνμ → νs

1−Pνμ → νμ

< 0.22 (0.40)αt90% C.L.no (with) νe appearance

R=Ndata −BG

SNC

1.09 ±0.06 (stαt.)±0.05 (syst.)(νo νe αππeαrανce)

1.01 ±0.06 (stαt.)±0.05 (syst.) (with νe αππeαrανce)

Page 34: New Results from MINOS

34νe Appearance

P. Vahle, Neutrino 2010

P(νμ → νe)≈siν2(2θ13)siν2(θ23)siν

2 1.27Δμ 312 LE

⎛⎝⎜

⎞⎠⎟ +

siν2(2θ12 )cos2(θ23)siν

2 1.27Δμ 212 LE

⎛⎝⎜

⎞⎠⎟ +

siν(2θ13)siν(2θ23)siν(2θ12 )siν 1.27Δμ 312 LE

⎛⎝⎜

⎞⎠⎟siν 1.27Δμ 21

2 LE

⎛⎝⎜

⎞⎠⎟cos 1.27Δμ 32

2 LE±δCP

⎛⎝⎜

⎞⎠⎟

A few percent of the missing νμ could change into νe depending on value of θ13

Appearance probability additionally depends on δCP and mass hierarchy

Δm322

Δm212

Normal Hierarchy Δm322

Δm212

Inverted Hierarchy?⇔

Page 35: New Results from MINOS

35

Looking for electron-neutrinos

P. Vahle, Neutrino 2010

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 νe each extrapolates differently take advantage of NuMI flexibility to separate

background components νe

selected region

• Data⎯ MC

BG RegionSee R. Toner, L. Whitehead, G. Pawloski poster

Page 36: New Results from MINOS

36νe Appearance Results

P. Vahle, Neutrino 2010

Based on ND data, expect: 49.1±7.0(stat.)±2.7(syst.)

Page 37: New Results from MINOS

37νe Appearance Results

P. Vahle, Neutrino 2010

Based on ND data, expect: 49.1±7.0(stat.)±2.7(syst.)

Observe: 54 events in the FD, a 0.7σ excess

Page 38: New Results from MINOS

38νe Appearance Results

P. Vahle, Neutrino 2010

for δCP =0, siν2 2θ23( )=1,

Δμ 322 =2.43×10−3 eV 2

siν2(2θ13) < 0.12 νorμ αl hierαrchy

siν2(2θ13) < 0.20 iνverteδ hierαrchyαt90%C.L.

arXiv:1006.0996v1 [hep-ex]

MINOS

7.01×1020 POT

Page 39: New Results from MINOS

39

Making an anti-neutrino beam

P. Vahle, Neutrino 2010

π-

π+

Target Focusing Horns 2 m

675 m

νμ

νμ

15 m 30 m

120 GeV p’s from

MI

Neutrino modeHorns focus π+, K+

νμ: 91.7% νμ: 7.0%νe+νe :1.3%

Even

ts

Page 40: New Results from MINOS

40

Making an anti-neutrino beam

P. Vahle, Neutrino 2010

π-

π+Target Focusing

Horns 2 m

675 m

νμ

νμ

15 m 30 m

120 GeV p’s from

MI

Anti-neutrino ModeHorns focus π-, K- enhancing the νμ flux

Neutrino modeHorns focus π+, K+

νμ:39.9% νμ:58.1%νe+νe :

2.0%

Even

ts

Even

ts

νμ: 91.7% νμ: 7.0%νe+νe :1.3%

Page 41: New Results from MINOS

41ND Anti-neutrino Data

P. Vahle, Neutrino 2010

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 posterAlso A. Blake poster on atmospheric neutrinos

Page 42: New Results from MINOS

42ND Data

P. Vahle, Neutrino 2010

Data/MC agreement comparable to neutrino running

Page 43: New Results from MINOS

43FD Data

P. Vahle, Neutrino 2010

No oscillation Prediction: 155

Observe: 97 No oscillations

disfavored at 6.3σ

Page 44: New Results from MINOS

44FD Data

P. Vahle, Neutrino 2010

Δm2 = 3.36−0.40+0.45 ×10−3eV2

sin2 (2θ ) = 0.86 ± 0.11

No oscillation Prediction: 155

Observe: 97 No oscillations

disfavored at 6.3σ

Page 45: New Results from MINOS

45FD Data

P. Vahle, Neutrino 2010

Page 46: New Results from MINOS

46Comparisons to Neutrinos

P. Vahle, Neutrino 2010

Page 47: New Results from MINOS

47Comparisons to Neutrinos

P. Vahle, Neutrino 2010

Page 48: New Results from MINOS

48Summary

P. Vahle, Neutrino 2010

With 7x1020 POT of neutrino beam, MINOS finds muon-neutrinos

disappear

NC event rate is not diminished

electron-neutrino appearance is limited

With 1.71x1020 POT of anti-neutrino beam muon anti-neutrinos also

disappear with

we look forward to more anti-neutrino beam!

Δm2 = 2.35−0.08+0.11 × 10−3eV2 ,

sin2 (2θ ) > 0.91 (90% C.L.)

fs < 0.22(0.40)αt90% C.L.

sin2 (2θ13) < 0.12 (0.20)αt 90%C.L.

Δm2 = 3.36−0.40+0.45 ×10−3eV2 ,

sin2 (2θ ) = 0.86 ± 0.11

Page 49: New Results from MINOS

49 Backup Slides

P. Vahle, Neutrino 2010

Page 50: New Results from MINOS

50

LE 10 ME HE

Neutrino Spectrum

P. Vahle, Neutrino 2010

Use flexibility of beam line to constrain hadron production, reduce uncertainties due to neutrino flux

Page 51: New Results from MINOS

51Near to Far

P. Vahle, Neutrino 2010

Far spectrum without oscillations is similar, but not identical to the Near spectrum!

Eν ≈0.43Eπ

1+γ2θν2

Page 52: New Results from MINOS

52Far/Near differences

P. Vahle, Neutrino 2010

νμ CC events oscillate awayEvent 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 intensityRelative energy calibration/energy resolution

Account for these lower order effects using detailed detector simulation

Page 53: New Results from MINOS

53

New Muon-neutrino CC Selection

P. Vahle, Neutrino 2010

Page 54: New Results from MINOS

54Shower Energy Resolution

P. Vahle, Neutrino 2010

Page 55: New Results from MINOS

55Energy Resolution Binning

P. Vahle, Neutrino 2010

Page 56: New Results from MINOS

56

CC Systematic Uncertainties

P. Vahle, Neutrino 2010

Dominant systematic uncertainties: hadronic energy

calibration track energy calibration NC background relative Near to Far

normalization

Page 57: New Results from MINOS

57Resolution Binning

P. Vahle, Neutrino 2010

Page 58: New Results from MINOS

58Contours by Run Period

P. Vahle, Neutrino 2010

Page 59: New Results from MINOS

59

Rock and Anti-fiducial Events

P. Vahle, Neutrino 2010

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

Page 60: New Results from MINOS

60Fits to NC

P. Vahle, Neutrino 2010

Fit CC/NC spectra simultaneously with a 4th (sterile) neutrino

2 choices for 4th mass eigenvalue m4>>m3 m4=m1

Page 61: New Results from MINOS

61

Electron-neutrino Background Decomposition

P. Vahle, Neutrino 2010

Page 62: New Results from MINOS

62

Electron-neutrino Systematics

P. Vahle, Neutrino 2010

Stats. Err.

Page 63: New Results from MINOS

63

MRCC Background Rejection Check

P. Vahle, Neutrino 2010

R

Neutrino Energy: 5.3 GeV

Muon Energy: 3.2 GeVRemnant Energy: 2.1 GeVANN PID: 0.86

Mis-id rate: pred (6.42±0.05)% data (7.2±0.9)%

(stats error only)Compatible at 0.86σ

Remove muons, test BG rejection on shower remnants

Page 64: New Results from MINOS

64Checking Signal Efficiency

P. Vahle, Neutrino 2010

Test beam measurements demonstrate electrons are well simulated

Page 65: New Results from MINOS

65Checking Signal Efficiency

P. Vahle, Neutrino 2010

Check electron neutrino selection efficiency by removing muons, add a simulated electron

Page 66: New Results from MINOS

66

P. Vahle, Neutrino 2010

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

Page 67: New Results from MINOS

67Anti-neutrino Selection

P. Vahle, Neutrino 2010

μ- Not Focused

Coil Hole

μ+ Focused

Coil Hole

Page 68: New Results from MINOS

68Anti-neutrino Systematics

P. Vahle, Neutrino 2010

Page 69: New Results from MINOS

69FD Anti-neutrino Data

P. Vahle, Neutrino 2010

Vertices uniformly distributed Track ends clustered around coil hole

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70

Previous Anti-neutrino Results

P. Vahle, Neutrino 2010

Results consistent with (less sensitive) analysis of anti-neutrinos in the neutrino beamanti-neutrinos from unfocused beam component

mostly high energy antineutrinos

Analysis of larger exposure on going

Page 71: New Results from MINOS

71

Future Anti-neutrino Sensitivity

P. Vahle, Neutrino 2010

Page 72: New Results from MINOS

72Atmospheric Neutrinos

P. Vahle, Neutrino 2010

Rν /νδαtα / Rν /ν

MC =1.04−0.10+0.11 ±0.10

Δμ 2 −Δμ 2 =0.4−1.2+2.5 ×10−3eV 2