1

735 km

The MINOS Long Baseline Neutrino Oscillation

Experiment

Jeff Nelson

William & Mary

Fermilab Users’ Meeting

June 6, 2007

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MINOS

• Overview

> Detector & beam

> Oscillation analysis

> Neutrino time of flight

• What’s New?

> 2nd year of running

> Advances

• Prospects Argonne • Athens • Benedictine • Brookhaven • Caltech • Cambridge Campinas • Fermilab • College de France • Harvard • IIT • Indiana

Minnesota-Twin Cities • Minnesota-Duluth • Oxford • Pittsburgh Rutherford • Sao Paulo • South Carolina • Stanford • Sussex • Texas

A&M • Texas-Austin • Tufts • UCL • William & Mary • Wisconsin

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MINOS Physics Goals

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2

1

321

321

321

UUU

UUU

UUU eeee• Test the νμ → ντ oscillation hypothesis

> Measure precisely |Δm232| & sin22θ23

• PRL 97, 191801 (2006)

> Search for / constrain exotic phenomena

• Search for νμ → νe oscillations

• Compare ν, ν oscillations> CPT test

• Neutrino interaction physics

• Atmospheric neutrinos > PRD 75, 092003 (2007)

> PRD 73, 072002 (2006)

• Cosmic rays> hep-ex/0705.3815

> 10 papers to ICRC 2007

See poster by Jeff de Jong

Useful Approximations

νμ disappearance (2 flavors):

P(νμ→νx) = 1 - sin22θ23 sin2(1.27Δm232 L/E)

νe appearance:

P(νμ→νe) ≈ sin2θ23sin22θ13sin2(1.27Δm231 L/E)

where L, E are experimental parameters & θ23, θ13, Δm2

32 are to be determined

Δm232 = m3

2 – m22

ν1

ν2

ν3ν1

ν2

ν3

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Example of a disappearance measurement

Look for a deficit of νμ events at a distance…

Unoscillated

Oscillated

νμ spectrum

Monte Carlo

NC background

Monte Carlo

Spectral ratio

NC subtracted0.0033 eV2

)E/Lm267.1(sinθ2sin-1=)νν(P 222μμ Δ→

Unoscillated

Oscillated

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Example of a disappearance measurement

Look for a deficit of νμ events at a distance…

Unoscillated

Oscillated

νμ spectrum

Monte Carlo

NC background

Monte Carlo

Spectral ratio

NC subtracted0.0033 eV2

)E/Lm267.1(sinθ2sin-1=)νν(P 222μμ Δ→

Unoscillated

Oscillated

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Example of a disappearance measurement

Look for a deficit of νμ events at a distance…

Unoscillated

Oscillated

νμ spectrum

Monte Carlo

NC background

Monte Carlo

Spectral ratio

NC subtracted0.0033 eV2

)E/Lm267.1(sinθ2sin-1=)νν(P 222μμ Δ→

Unoscillated

Oscillated

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Producing the neutrino beam (NuMI)

• 120 GeV protons strike target>10 s pulse every ~2.4s>Typically running at 2.5e13 protons per pulse

• 2 magnetic horns focus secondary π/K• π/K decays produce neutrinos

>Moveable target & horn provides variable beam energy

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MINOS Detectors

Iron and Scintillator tracking calorimetersmagnetized steel planes <B> = 1.2T

1×4.1 cm2 scintillator strips

Multi-anode PMT readout

GPS time-stamping to synchronize FD data to ND/Beam

Main Injector spill times sent to the FD for a beam trigger

Far Detector5.4 kton

8 8 30 m3

484 planes

Near Detector1 kton

3.8 4.8 15 m3

282 steel planes

153 scintillator planes

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1pe PMT cross-talk

A 2 GeV νμ event in the far detector

Track Energy 2.04 GeV

Shower energy 0.20 GeV

q/p = -0.52 ± 0.03

< 2 PE

2 < PE < 20 PE

> 20 PE

Track hit

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Energy spectra in ND

LE10 pME pHE

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Energy spectra in ND

LE10 pME pHE

Data & Nominal MC discrepancy changes energy with beam tuneSuggests production of hadrons off the target is to blame

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Energy spectra in ND

LE10 pME pHE

• Took data in 6 different beam tunes (only 3 shown)• Varied the dependence on pT and x

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MINOS best-fit spectrum for 1.27×1020 POT

Measurement errors are 1 sigma, 1 DOF

See poster by Niki Saoulidousyst)+(stat1.00=2θsin

eV10×syst)+(stat2.74=Δm

0.13232

2-3+0.440.26 -

232

-

PRL 97, 191801 (2006)

Systematics Δm2 (10-3 eV2)

sin22θ

Near/Far normalization 0.05 0.01

Absolute hadronic scale 0.06 0.05

NC contamination 0.09 0.05

All other systematics 0.04 0.01

Total systematic error 0.13 0.07

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MINOS allowed region for 1.27×1020 POT

Measurement errors are 1 sigma, 1 DOF

See poster by Niki Saoulidou

PRL 97, 191801 (2006)

syst)+(stat1.00=2θsin

eV10×syst)+(stat2.74=Δm

0.13232

2-3+0.440.26 -

232

-

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MCMC

Projected MINOS sensitivity

Statistical errors

90% C.L.

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Prospects

• Neutrino time of flight• New data

>2nd year running experience>Post-shutdown intensity

• Prospects for future >Advancing the oscillation analysis >Electron neutrino appearance>Neutral current>Antineutrinos>Non oscillation physics

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Neutrino Time of Flight(TOF)

• PDG limit is> |v−c|/c < 4 × 10-5 (95% C.L.)

> Exotic models predict values all the way up to this limit

• Separation between the detectors> L = 734,298.6 ± 0.7 m

• The TOF for a massless particle

> τ = 0.002449356 s

δ = -126 ± 32 (stat) ± 64 (syst.) ns

(v−c)/c = [5.1 ± 2.9 (syst. + stat.)] × 10-5 (68% CL)

hepex/0706.0437

δ (μs)

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Neutrino Time of Flight (TOF)

• PDG limit is> |v−c|/c < 4 × 10-5 (95% C.L.)

> Exotic models predict values all the way up to this limit

• Separation between the detectors> L = 734,298.6 ± 0.7 m

• The TOF for a massless particle

> τ = 0.002449356 s

δ = -126 ± 32 (stat) ± 64 (syst.) ns

(v−c)/c = [5.1 ± 2.9 (syst. + stat.)] × 10-5 (68% CL)

δ (μs)

hepex/0706.0437

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Relativistic mass measurement

• Use time and energy to compute a relativistic mass limit> If the neutrino have mass mv

its time of flight would be

where τ is the TOF for a massless particle

• We find> The limit is driven by the few points near edge

> With full data MINOS dataset ~10 MeV at 99% C.L.

Line = 68% C.L.Shaded = 99% C.L.

C.L. 68% MeV/c syst)+(stat17=m 2+33 56- ν

( )( )

νν

νmcm

τν

/E1=ET

2

hepex/0706.0437

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The 2nd year of MINOS running

1st year of running (published dataset)

Double datasetCollected with 99.4% live time

More !

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MI intensity improvements: slip stacking

• MI currently running in “2+5” slip stacking> 2 MI bunches for pbar

> 5 MI bunches for NuMI

• AD demonstrated “2+9” slip stacking> 2 MI bunches for pbar

> 9 MI bunches for NuMI

• New record for beam in the MI set in April

> 4.608×1020 POT with good transport efficiency

> Beam delivery limited to 4.0x1020 POT until we have a spare target in-hand (this summer)

• AD plans “2+9” as default after the shutdown

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How to we plan to exploit this new data?

• Modeling & reconstruction>Additional data at higher energies

>Updated flux model

>New hadronization & intranuclear scattering models

> Improved reconstruction & PID algorithms • Reduce NC systematic errors

>Ongoing improvements in calibration

• Working to extend the oscillation analysis to antineutrinos & higher energies

MC

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Since initial analysis, implemented beam fitting to antineutrinos

• Antineutrinos come from π - off the target> Rates shown are for normal running conditions

• Simultaneous neutrino and antineutrino fit > Compared to new p+C data from CERN NA49

Eur.Phys.J.C49:897-917,2007

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High energy neutrinos and kaon production

• Kaons decays tend to produce higher energy neutrinos> MIPP took p+C thin

target data at 120-GeV/c

• MIPP took thick-target data with our NuMI target> Forthcoming

K

ra

tio

pT<0.2 GeV/c

0.2<pT<0.4 GeV/c

Andre Lebedev, Harvard Ph.D., MIPP-doc-218

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→ e oscillation search

See poster by Tingjun Yang4×1020 POT

16×1020 POT

P(νμ→νe) ≈ sin2θ23 sin22θ13 sin2(1.27Δm231L/E)

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Tuned MC incl. systematic error

Neutral current (NC) events

• NC unaffected by νμ ντ oscillations

> Can test for sterile neutrino contributions

• Near detector NC energy spectrum> Far Detector data for this

analysis is still blinded

> Currently working on • Near/Far extrapolation

• FD systematic error evaluation

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Neutrino scattering in the near detector

• Intense NuMI beam > Recorded 3 ×1020 POT> 5 × 106 events in the fiducial volume

• Can explore new kinematic regions> Connect to precision higher energy

experiments

• Some non-oscillation analyses underway

> Total CC differential cross-section> Flux extraction> DIS differential cross-section> Structure functions> Quasi elastic scattering> Coherent production cross-section …

MC

See poster by Minsuk Kim MC

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Conclusions

Results from the first year of accelerator neutrino exposure

> It is consistent with νμ disappearance with the following parameters

> Data also used to measure the TOF and relativistic mass of neutrinos

(v−c)/c = (5.1 ± 2.9) × 10-5 (68% CL, syst. + stat.)

More than doubled the dataset since shutdown> Slip stacking offers the prospect of significant intensity

improvements after the shutdown

New analyses are underway on a number of samples

syst)+ (stat1.00=2θsin

eV10×syst)+(stat2.74=Δm

0.13232

2-3+0.440.26-

232

-

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MI intensity improvements with slip stacking

• MI currently running in “2+5” slip stacking mode> 2 MI bunches for pbar> 5 MI bunches for NuMI

• AD demonstrated “2+9” slip stacking mode> 2 MI bunches for pbar> 9 MI bunches for NuMI

• New record for beam in the MI set in April> 4.608E13 POT with good transport efficiency > Beam delivery limited to 4.0E13 POT until we have

a spare target in-hand (this summer)

• AD plans “2+9” as default after the shutdown> The intensity to be gradually increased from

2.4E13 POT> AD continuing preparations for the MI collimator

installation during the shutdown

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• Look for e appearance

> P(νμ→νe) ≈ sin2θ23 sin22θ13 sin2(1.27Δm231L/E)

(plus CP violation and matter effects)

• Look for events with compact shower and typical EM profile> Primary background from NC events

> Matter effects alter e yield by 20%

• Reach depends strongly on POT> Far Detector data for this

analysis is still blinded

> 4×1020 POT - can challenge the world’s best limit (CHOOZ)

> 16×1020 POT - can significantly improve limit and increase chance of discovery

→ e oscillation search

See poster by Tingjun Yang

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Tuned MC incl. systematic error

Neutral current (NC) events

• NC interactions> Unaffected by νμ ντ

oscillations• Can test for sterile neutrino

contributions

> Large cross-section uncertainty for E ~1 GeV

• Near detector NC energy spectrum> Far Detector data for this

analysis is still blinded > Currently working on

• Near/Far extrapolation

• FD systematic error evaluation

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Neutrino scattering in the near detector

• Intense NuMI beam offers opportunities for exploring cross-sections> Recorded 3×1020 POT> We have 5.5×106 CC interactions

in the fiducial volume• Some non-oscillation analyses

underway> Total CC differential cross-section> Flux extraction> DIS differential cross-section> Structure functions> Quasi elastic scattering> Coherent production cross-section

• A few examples of work in progress… MC

See poster by Minsuk Kim for more

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Deep Inelastic Scattering

• Largest component of the MINOS event sample> The measurement will be systematics

limited

• Can explore new kinematic regions> Connects to precision higher energy

experiments

MC

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Quasi elastic scattering(vn → μp)

• The QE-enhanced sample can be used to extract the flux for MA measurement> 3×1020 POT

~ 800,000 events> Look for

• Well-defined muon track

• Low shower energy

• Low W

• Main background> Single charged pions