Analysis of and e events from NuMI beamline at MiniBooNE Zelimir Djurcic (a) and Zarko Pavlovic (b)...

Analysis of Analysis of and and ee events from events from NuMI beamline at MiniBooNENuMI beamline at MiniBooNE

Zelimir Djurcic Zelimir Djurcic (a)(a) and Zarko Pavlovic and Zarko Pavlovic (b)(b)

(a)(a) Columbia UniversityColumbia University

(b) University of Texas Austin(b) University of Texas Austin

Zelimir Djurcic Zelimir Djurcic (a)(a) and Zarko Pavlovic and Zarko Pavlovic (b)(b)

(a)(a) Columbia UniversityColumbia University

(b) University of Texas Austin(b) University of Texas AustinOutline of this Presentation1. Off-axis Neutrino Beam2. NuMI flux at MiniBooNE3. MiniBooNE Detector and Reconstruction4. CC Sample5. NC Sample6. CC e Sample

Analysis Motivation Analysis Motivation

Joint collaboration between MiniBooNE and NuMI.

Observation and analysis of an off-axis beam.

Measurement of /K components of the NuMI beam.

Check of CCQE and e CCQE interactions independent from Booster beam neutrinos.

e-rich sample to study MiniBooNE reconstruction and particle identification algorithms.

Performing physics analysis complementary to MinibooNE analyses.

NuMI Beam and MiniBooNE DetectorNuMI Beam and MiniBooNE Detector

NuMI events (for MINOS) detected in MiniBooNE detector!

MiniBooNE detector is 745 meters downstream of NuMI target.MiniBooNE detector is 110 mrad off-axis from the target

along NuMI decay pipe.

p beam , K

The Woes of Knowing the flux

• For wide-band(*) neutrino beams,– Use MC simulation

• Particle production• Focusing

– Measure in the detector• Use some process with known cross

section

• History has several examples of substantial corrections to these estimates– ANL 12’ B.C. in ZGS horn beam– FNAL 15’ B.C., 400GeV horn beam– BNL E734, AGS horn beam– Gargamelle, CERN PS beam

(*) Narrow-band beams can more readily measure fluxes directly

Borodovsky et al., Phys. Rev. Lett. 68, 274 (1992)(BNL E776 ) got flux correct, right ‘out of the box’

Off axis beam

TargetHornsDecay Pipe

DetectorFirst Proposedby BNL-E889

• On-axis, neutrino energy more tightly related to hadron energy

• Off-axis, neutrino spectrum is narrow-band and ‘softened’

• Easier to estimate flux correctly: all mesons decay to same energy .

Future off axis experiments

• NOvA– NuMI off-axis beam– 810km baseline– 14.5mrad; Enu~2GeV

• T2K– J-PARC 50GeV proton beam– Use SK as Far detector 295km

away– 35 mrad; Enu~0.6GeV

• Use off-axis trick for optimized e search

On-axis beam

Off-axis beam

NuMI Off-axis Beam at MiniBooNE

K

stopped K

stopped • Opportunity to demonstrate off-axis technique

• Known spectral features from , K decays

• Expected energy spectra softened to within MiniBooNE acceptance

NuMI as a “e Source”

• NuMI off-axis beam produces strong flux in both and e flavors.

• The e’s are helpful to study the MiniBooNE detector.

• Hopefully one can do some physics with a ‘enhanced’ e beam

• NuMI on-axis e ~1% NuMI off-axis e ~6%BNB on-axis e ~0.5%

K

stopped K

NuMI Spectrum is “Calibrated”• Extensive experience with MINOS data

• MINOS acquired datasets in variety of NuMI configurations

• Tuned kaon and pion production (xF,pT) to MINOS data

MINOS MINOS • Same parent hadrons produce neutrinos seen by MiniBooNE

• Flux at MiniBooNE should be well-described by NuMI beam MC?

D.G. Michael et al, Phys. Rev. Lett. 97:191801 (2006)

D.G. Michael et al, arXiv:0708.1495 (2007)

Two views of the same decays• Decays of hadrons produce neutrinos that strike both MINOS and

MiniBooNE• Parent hadrons ‘sculpted’ by the two detectors’ acceptances.• Plotted are pT and p|| of hadrons which contribute neutrinos to MINOS

(contours) or MiniBooNE (color scale)

MINOS

MiniBooNE MINOS

MiniBooNE

Neutrino Sources along NuMI beam

• Higher energy neutrinos mostly from particles created in target

e

MiniBooNE

• Interactions in shielding and beam absorber contributes in lowest energy bins

• Colors indicate theorigin of parents

diagram not to scale!

Flux Uncertainties• Focusing uncertainties are negligible• Uncertainty is dominated by production of hadrons

– off the target (estimated from MINOS tuning)– in the shielding (estimated in gfluka/gcalor)– in beam absorber (estimated in gfluka, 50% error assigned)

stopped mesons excluded in this plot

MINOSTuning

MiniBooNEMiniBooNE

((BooBoosterster N Neutrinoeutrino E Experiment)xperiment)

becomesbecomes

An off axis neutrino experimentAn off axis neutrino experimentusing Main Injectorusing Main Injector

NuMI Beam and MiniBooNE NuMI Beam and MiniBooNE DetectorDetector

NuMI events (for MINOS) detected in MiniBooNE detector!

MiniBooNE Detector:MiniBooNE Detector:12m diameter sphere12m diameter sphere950000 liters of 950000 liters of oiloil(CH2)1280 inner PMTs1280 inner PMTs240 veto PMTs240 veto PMTs

p beam , K

Main trigger is an accelerator signal indicating a beam spill.Information is read out in 19.2 s interval covering arrival of beam.

Detector Operation and Event Detector Operation and Event reconstructionreconstruction

No high level analysis needed to see neutrino events

Backgrounds: cosmic muons and decay electrons->Simple cuts reduce non-beam backgrounds to ~10-5

Events in DAQ window:no cuts

Removed cosmic ray muons:PMT veto hits < 6

Removed cosmic ray muonsand -decay electrons:PMT veto hits < 6 andPMT tank hits > 200

6-batch structure of MIabout 10 s durationreproduced.

Detector Operation and Event Detector Operation and Event reconstructionreconstruction

The data set analyzed here: 1.42 x 1020 P.O.T. We have a factor two more data to analyze!

The rate of neutrino candidates was constant: 0.51 x 10-15 /P.O.T.Neutrino candidates counted with:PMT veto hits < 6 and PMT tank hits > 200

0 →

electron

candidate

candidate

0

candidate

Čerenkov rings provide primary means of identifying products of interactions in the detector

n - p

e n e- p

p p 0

n n

Particle IdentificationParticle Identification

Events from NuMI detected at MiniBooNEEvents from NuMI detected at MiniBooNE

CCQE 39% CC ++ 26% NC 00 9%

Neutrino interactions at carbon simulated by NUANCE event generator: neutrino flux converted into event rates.

Eventrates

Eventrates

Flux

NuMI event composition at MB -81%, e-5%,-13%,e-1%

Analysis AlgorithmAnalysis Algorithm

To reconstruct an event:-Separate hits in beam window by time into sub-events of related hits.-Reconstruction package maximizes likelihood of observed charge and time distribution of PMT hits to find track position, direction and energy (from the charge in the cone) for each sub-event.

Event Event Reconstruction Reconstruction

The tools used in the analysis here are developed and verifiedin MiniBooNE oscillation analysis of events from Booster beam.

Phys. Rev. Lett. 98, 231801 (2007), arXiv:0704.1500 [hep-ex]

Details:

and arXiv:0706.0926 [hep-ex]Accepted for publ. by Phys.Rev.Lett.

Event selection very similar to what was used in MiniBooNE analyses.

Uses detailed, direct reconstruction of particle tracks, and ratio of fit likelihoods to identify particles.

Analysis Method Analysis Method

Apply likelihood fits to three Apply likelihood fits to three hypotheses:hypotheses:-single electron track-single electron track-single muon track-single muon track-two electron-like rings (-two electron-like rings (0 0 event event hypothesis )hypothesis )

Compare observed light distribution to fit prediction:

Does the track actually look like an electron?

log(Le/L)<0 -like events

log(Le/L)>0 e-like events

Example from MiniBooNEOscillation Analysis.

log(Le/L)

Form likelihood differences using minimized –logL quantities: log(Le/L) and log(Le/L)

e

CCQE AnalysisCCQE Analysis

Analysis of the Analysis of the CCQE events from NuMI CCQE events from NuMI

beambeam

e

CCQE (+n +p) has a two “subevent” structure

(with the second subevent from stopped e e)

Event Selection:Subevent 1: Thits>200, Vhits<6 R<500 cm Le/L < 0.02

Subevent 2:

Thits<200, Veto<6

p

nScintillation

Cerenkov 1

12C Cerenkov 2

e

Tank Hits

This sample contains 18000 eventsof which 70% are CCQE’s.

Log(Le/L)< 0.02

Visible E of Visible E of : final state interactions in : final state interactions in CCQE CCQE

samplesample

Data (stat errors only)compared to MC predictionfor visible energy in the tank.

Visible energy in tank [GeV]

CCQECC++

Monte Carlo

Data

PRELIMIN

ARY

PRELIMIN

ARY

CCQE

CC++

“other”

Total MCNX0

Beam e

p n pn n+

Other Events Events Events

e

K

Compare Compare CCQE MC to Data:Parent CCQE MC to Data:Parent

ComponentsComponents

MC is normalized to data POT number with no further corrections!


Beam MC tunedwith MINOS neardetector data.

Cross-sectionMonte Carlotuned with MBmeasurement ofCCQE pars MA

and .PRELIM

INARY

PRELIMIN

ARY

arXiv:0706.0926 [hep-ex]

K

Compare Compare CCQE MC to Data:Parent CCQE MC to Data:Parent

ComponentsComponents

Predicted Kaons are matching the data out of box!


PRELIMIN

ARY

PRELIMIN

ARY

Systematic Uncertainties in Systematic Uncertainties in CCQE CCQE

analysisanalysis To evaluate Monte Carlo agreement with the data need estimateof systematics from three sources:-Beam modeling: flux uncertainties.-Cross-section model: neutrino cross-section uncertainties. -Detector Model:describes how the light emits, propagates, and absorbs in the detector (how detected particle looks like?).

Detector Model Cross-section

Beam Total Visible energy [GeV]

Visible energy [GeV]



PRELIMIN

ARY

PRELIMIN

ARY

PRELIMIN

ARY

PRELIMIN

ARY

Add Systematic uncertainty to Add Systematic uncertainty to CCQE Monte CCQE Monte CarloCarlo

visible energy distribution


Outgoing angular distribution

cos

Information aboutincoming :wrt NuMItarget direction.

K

K

Predicted Pions are matching the data within systematics!

PRELIMIN

ARY

PRELIMIN

ARY

PRELIMINARY

PRELIMINARY

Understanding of the beam demonstrated:MC is normalized to data POT number !

Reconstructed E QE:from

Elepton

(“visible energy”) and lepton angle wrt neutrino direction

CCQE sample: Reconstructed energy CCQE sample: Reconstructed energy EE of of

incoming incoming

K

PRELIMIN

ARY

PRELIMIN

ARY

This is the first demonstration of the off-axis principle.

There is very good agreement between data and Monte Carlo:the MC need not be tuned.

Conclusion from Conclusion from CCQE analysis CCQE analysis

sectionsection

Because of the good data/MC agreementin flux and because the and e

share same parents the beam MC can now be used to predict:e rate, andmis-id backgrounds for a e analysis.

ee CCQE Analysis CCQE Analysis

When we try to isolate a sample of ee candidateswe find background contribution to it:--00 ( (00) and radiative ) and radiative ( (NN) events, ) events, andand-”dirt” events. -”dirt” events.

Backgrounds to Backgrounds to ee CCQE sample CCQE sample

e CCQE (+n e+p)

Therefore, before analyzing e CCQE we constrain thebackgrounds by measurement in our own data.

Strategy:Don’t try to predict the 0 mis-id rate, measure it!Measured rates of reconstructed 0…tie down the rate of mis-ids

decays to a single photon:with 0.56% probability:

Analysis of Analysis of 00 events from NuMI events from NuMI beam beam

What is applied to select 00sEvent pre-selection:1 subeventThits>200, Vhits<600R<500 cm

log(Le/L)>0.05 (e-like) log(Le/L)<0 (0-like)

Among the e-like mis-ids, 0 decays which are boosted, producing 1 weak ring and 1 strong ring is largest source.

p+ 0

p

pp+

p

Analysis of Analysis of 00 events from NuMI beam: events from NuMI beam: 00 massmass

This sample contains 4900 events of which 81% are 0 events: world second largest 0

sample!

The peak is 135 MeV/c2

e appear to be well modelled.

Monte Carlo

Data

00

e

Analysis of Analysis of 00 events from NuMI beam: events from NuMI beam: 00 massmass

The peak is 135 MeV/c2

Monte Carlo

Data

00

e

The 0 events are well modeled withno corrections to the Monte Carlo!

Analysis of Analysis of 00 events from NuMI beam: events from NuMI beam: 0 0

momentummomentum

We declare good MC/Data agreement for 0 0 sample going down to low massregion where ee

candidates are showing up!

Monte Carlo

Data

00

e

FurtherCrossCheck!

PRELIMIN

ARY

PRELIMIN

ARY

Analysis of Analysis of dirtdirt events from NuMI events from NuMI beam beam

- “Dirt” background is due to interactions outside detector. Final states (mostly neutral current interactions) enter the detector.

- Measured in “dirt-enhanced” samples:- we tune MC to the data selecting a sample

dominated by these events. -”Dirt” events coming from outside deposit only a fraction of original energy closer to the inner tank walls.--Shape of visible energy and event vertex distance-to-wall distributions are well-described by MC: good quantities to measure this background - component.

shower

dirt

Selecting the Selecting the dirtdirt events events

Event pre-selection:1 subeventThits>200, Vhits<600R<500 cm

log(Le/L)>0.05 (e-like)

Ee <550 MeV

Distance-to-wall <250 cm

m<70 MeV/c2 (not 0-like)

Dist-to-wall of tank along track [m]


Even

ts/

bin

Even

ts/

bin

Dirt sample

interactionsin the tank

Uncertainty in the dirt rate is less than 20%.

Fits to dirt enhanced sample:

We declare good MC/Data agreement for

the dirtthe dirt

sample.

PRELIMIN

ARY

PRELIMIN

ARY

Analysis of Analysis of ee events: do we see data/MC events: do we see data/MC

agreement?agreement?

Analysis of the Analysis of the ee CCQE events from NuMI CCQE events from NuMI

beambeame CCQE (+n e+p)

1 SubeventThits>200, Vhits<6R<500 cm, EEee>200MeV

Likelihood cuts as the as shown below

+

Likelihood e/ cut Likelihood e/ cut Mass(0) cut

Cut region

Cut regionCut region

Signal regionSignal region

Signal region

Visible energy [MeV]



MC example plots here come from Booster beam MC

MC example plots here come from Booster beam MC

EEee>200MeV cut is appropriate to remove e contribution from the dump

that is hard to model.

Visible energy of Visible energy of ee CCQE events CCQE events

Before we further characterize data/MC agreement we Before we further characterize data/MC agreement we

have to account for the systematic uncertaintieshave to account for the systematic uncertainties..

Data = 783 events.Monte Carlo prediction = 662 events.


Monte Carlo

Data

00

e

Other

dirt

PRELIM

INARY

PRELIM

INARY

Systematic Uncertainties in Systematic Uncertainties in ee CCQE CCQE

analysisanalysis Detector Model Cross-section

Beam Total Visible energy [GeV]




PRELIMIN

ARY

PRELIMIN

ARY

PRELIMIN

ARY

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““dirt” component of Xsec: 20% error; dirt” component of Xsec: 20% error; 00 component of Xsec: 25% error component of Xsec: 25% error

ee CCQE events: e visible energy and angular CCQE events: e visible energy and angular distributiondistribution

e visible energy distribution

Outgoing e angular distribution


cos e

All

All

K

KL

PRELIMIN

ARY

PRELIMIN

ARY

PRELIMINARY

PRELIMINARY

Outgoing electron angular Outgoing electron angular distributiondistribution

ee CCQE sample: CCQE sample: Reconstructed energy Reconstructed energy EE of of

incoming incoming

All

All e

PRELIMIN

ARY

PRELIMIN

ARY

E QE [MeV] 200-900 900-3000

total background 401±66 261±50 e intrinsic 311 231 induced 90 30 NC 0 30 25 NC →N 14 1 Dirt 35 1 other 11 3 Data 498±22 285±17 Data-MC 9770 2453Significance 1.40 0.45

Summary of estimated backgrounds vs data Summary of estimated backgrounds vs data ee CCQE CCQE samplesample

At this point systematic errors are large: we cannot saymuch about the difference between low and high-E regions.

In the future we will reduce ee CCQE sample systematics constraining it with our large statistics CCQE sample.

Looking quantitative into low energy and high energy region:

Summary and Future StepsSummary and Future Steps

We performed analyses of neutrinos from NuMI beam observed with MiniBooNE detector. The sample analyzed here corresponds to 1.42x 1020 protons on NuMI target.

We observed good description of the data by Monte Carlowith both CCQE and ee CCQE sample: successfuldemonstration of an off-axis beam at 110 mrad.

CCQE sample demonstrated proper understanding of thePion and Kaon contribution to neutrino beam.

PRELIMIN

ARY

PRELIMIN

ARY

In the future we will reduce ee CCQE sample systematics constraining it with our large statistics CCQE sample.

The ee CCQE sample will be compared to what we observed with Booster beam.

We are currently reprocessing and collecting more data(expect about 3 x 1020 P.O.T. collected by now.)

These errorswill be reduced

PRELIMIN

ARY

PRELIMIN

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BackupsBackups

Neutrino Sources along NuMI beam

• Higher energy neutrinos mostly from particles created in target

• Interactions in shielding and beam absorber contributes in lowest energy bins

NuMI Off-axis Beam at MiniBooNE

stopped K

stopped

• 1st opportunity to demonstrate off-axis technique

• Known spectral features from , K decays

• Expected energy spectra softened to within MiniBooNE acceptance

stopped K

NuMI as a “e Source”

• NuMI off-axis beam produces strong flux in both and e flavors. • The e’s are helpful to study the MiniBooNE detector.• Hopefully one can do some physics with a ‘pure’ e beam (only a few past

proposals on how to build such a beam).

Detector ModelingDetector Modeling

Detector (optical) model defines how light of generated event is propagated and detected in MiniBooNE detector

Sources of light: Cerenkov (prompt, directional cone),and scintillation+fluorescence of oil (delayed, isotropic)

Propagation of light: absorption, scattering (Rayleigh and Raman) and reflection at walls, PMT faces, etc.We have developed 39-parameter “Optical Model”.

Strategy to verify model:External Measurements: emission, absorption of oil, PMT properties.Calibration samples: Laser flasks, Michel electrons, NC elastic events.Validation samples: Cosmic muons (tracker and cubes).

MINOS, NuMIK2K, NOvAMiniBooNE, T2K

Super-K atmospheric

Predictions from NUANCE

- MC which MiniBooNE uses - open source code - supported & maintained by D. Casper (UC Irvine)

- standard inputs

- Smith-Moniz Fermi Gas - Rein-Sehgal 1 - Bodek-Yang DIS

Low energy Low energy cross cross sectionssections

Imperative is to preciselypredict signal & bkgd ratesfor future oscillation experiments

We need data on nuclear targets!(most past data on H2, D2)

MAQE, elo

sf 6%, 2% (stat + bkg only) QE norm 10% QE shape function of E

e/ QE function of E

coh/res ratio NC 0 norm 25% Nrate 7% BF

EB, pF 9 MeV, 30 MeVs 10% MA

1 25% MA

N 40% DIS 25%

Determined fromMiniBooNE QE data

MiniBooNE dataOther Experiments

Determined from other experiments

Cross-section uncertainties in the Cross-section uncertainties in the analysisanalysis

Michel electrons from decay: provide E calibration at low energy (52.8 MeV), good monitor of light transmission, electron PID

0 mass peak: energy scale & resolutionat medium energy (135 MeV), reconstruction

We have calibration sources spanning wide range of energies and all event types !

12% E res at

52.8 MeV

Energy CalibrationEnergy Calibration

cosmic ray + tracker + cubes: energy scale & resolution at high energy (100-800 MeV), cross-checks track reconstruction

provides tracks of known length → E

e

Are the neutrinos coming from the target?Are the neutrinos coming from the target?

Geological Survey: Y=24.80,XZ=87.50.

Measurement of exiting muons from neutrino interaction: Y=24.40,XZ=87.250

.


CCQE events: QCCQE events: Q2 2 distribution distribution

Efficiency :

Log(Le/L) + Log(Le/L) + invariant mass

“Precuts” +

PID cuts efficiency for PID cuts efficiency for ee CCQE events CCQE events

log(Le/L)>0 favors electron-like hypothesis

Separation is clean at high energies where muon-like events are long.

e CCQE

CCQEMC

Rejecting “Rejecting “-like” events -like” events

This does not separate e/0 as photon conversions are electron-like.

MC

0 mass cut log(Le/L) cut

NC 0

e CCQE NC 0

e CCQE

Rejecting “Rejecting “00-like” events-like” events

00 mass in mass in 00 momentum momentum binsbins

0 0 momentum bins are: 0<PP <0.2, 0.2<PP <0.3,0.3<PP <0.4, 0.4<PP <0.5,0.5<PP <0.6, 0.6<PP <0.8,0.8<PP <1.0, 1.0<PP <1.2,1.2<PP <1.6,and PP

>1.6GeV/c2

00 momentum momentum

In an analysis of neutral 0 0 sample from Boosterbeam we used thisdistribution to tuneMC to data: no need to do it here.

Selecting the Selecting the dirtdirt events events

Event pre-selection:1 subeventThits>200, Vhits<600R<500 cm

log(Le/L)>0.05 (e-like)

Ee <550 MeV

Distance-to-wall <250 cm

m<70 MeV/c2 (not 0-like) True energy:

Does the dirt sample constrain events in Does the dirt sample constrain events in ee CCQE CCQE

sample?sample?

Lets use ee CCQE cuts + “dirt” cuts: this is the CCQE cuts + “dirt” cuts: this is the overlap:overlap:

cos e

Visible energy of Visible energy of ee CCQE events: systematic CCQE events: systematic uncertaintyuncertainty



Visible energy of Visible energy of ee CCQE events with dirt CCQE events with dirt cutscuts



coscosee and E and Eee of of ee CCQE events with dirt cuts CCQE events with dirt cuts

cos e

• Anomaly Mediated Neutrino-Photon Interactions at Finite Baryon Density (arXiv:0708.1281: Jeffrey A. Harvey, Christopher T. Hill, Richard J. Hill)

• CP-Violation 3+2 Model: Maltoni & Schwetz, arXiv:0705.0107

• Extra Dimensions 3+1 Model: Pas, Pakvasa, & Weiler, Phys. Rev. D72 (2005) 095017

• Lorentz Violation: Katori, Kostelecky, & Tayloe, Phys. Rev. D74 (2006) 105009

• CPT Violation 3+1 Model: Barger, Marfatia, & Whisnant, Phys. Lett. B576 (2003) 303

• New Light Gauge Boson: Nelson & Walsh, arXiv:0711.1363

We have an indication of data over MC excess We have an indication of data over MC excess below 0.9 GeV with 1.4below 0.9 GeV with 1.4 significance: could it be significance: could it be

due to a signal?due to a signal?

Analysis of and e events from NuMI beamline at MiniBooNE Zelimir Djurcic (a) and Zarko Pavlovic (b)...

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