first results from miniboone eric prebys, fnal/boone collaboration
TRANSCRIPT
First Results from MiniBooNEFirst Results from MiniBooNE
Eric Prebys, FNAL/BooNE Collaboration
HEP Seminar, UT Austin, April 30th, 2007 – E. Prebys 2
University of Alabama Los Alamos National LaboratoryBucknell University Louisiana State UniversityUniversity of Cincinnati University of MichiganUniversity of Colorado Princeton UniversityColumbia University Saint Mary’s University of MinnesotaEmbry Riddle University Virginia Polytechnic InstituteFermi National Accelerator Laboratory Western Illinois UniversityIndiana University Yale University
The MiniBooNE CollaborationThe MiniBooNE Collaboration
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OutlineOutline
State of neutrino mixing measurements History and background Without LSND LSND and Karmen
Experiment Beam Detector Calibration and cross checks Analysis
Results Future Plans and outlook
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The Neutrino “Problem”The Neutrino “Problem”
1968: Experiment in the Homestake Mine first observes neutrinos from the Sun, but there are far fewer than predicted. Possibilities: Experiment wrong? Solar Model wrong? ( believed by most not involved) Enough created, but maybe oscillated (or decayed to
something else) along the way. ~1987: Also appeared to be too few atmospheric muon
neutrinos. Less uncertainty in prediction. Similar explanation.
Both results confirmed by numerous experiments over the years.
1998: SuperKamiokande observes clear oscillatory behavior in signals from atmospheric neutrinos. For most, this establishes neutrino oscillations “beyond a reasonable doubt”
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Theory of Neutrino OscillationsTheory of Neutrino Oscillations
Neutrinos are produced and detected as weak eigenstates (e ,, or ). These can be represented as linear combination of mass eigenstates. If the above matrix is not diagonal and the masses are not equal, then the net weak
flavor content will oscillate as the neutrinos propagate. Example: if there is mixing between the e and :
then the probability that a e will be detected as a after a distance L is:
E
LmP e
222 27.1sin2sin)(
2
1
cossin
sincos
e
)eV(in 221
22 mm
Distance in km
Energy in GeV
Mass eigenstatesFlavor eigenstates
Only measure magnitude of the difference of the squares of the masses.
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Probing Neutrino Mass DifferencesProbing Neutrino Mass Differences
& Reactors
Accelerators use decay to directly probe e
Reactors use use disappearance to probe e Cerenkov detectors directly measure and e content in atmospheric neutrinos. Fit to e mixing hypotheses
Solar neutrino experiments typically measure the disappearance of e.
Different experiments probe different ranges of E
L Path length
Energy
Also probe with new generation of “long baseline” accelerator and reactor experiments, MINOS, T2K, etc
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Best Three Generation Picture (all experiments but LSND)Best Three Generation Picture (all experiments but LSND)
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The LSND Experiment (1993-1998)The LSND Experiment (1993-1998)
Signature Cerenkov ring from
electron Delayed from
neutron capture
~30 m
Energy 20-50 MeV
e
e
e
mix
nepe
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LSND ResultLSND Result
(Soudan, Kamiokande,MACRO, Super-K)
(Homestake, SAGE,GALLEX, Super-KSNO, KamLAND)
Excess Signal: Best fit:
Only exclusive appearance result to date Problem: m2 ~ 1 eV2 not consistent with other
results with simple three generation mixing
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PossibilitiesPossibilities
4 neutrinos? We know from Z lineshape there are only 3 active
flavors Sterile?
CP or CPT Violation? More exotic scenarios? LSND Wrong? Can’t throw it out just because people don’t like it.
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m5
3+2 models
hep-ph/0305255
Accommodating a Positive SignalAccommodating a Positive Signal
We know from LEP that there are only 3 active, light neutrino flavors.
If MiniBooNE confirms the LSND results, it might be evidence for the existence of sterile neutrinos
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Karmen II Experiment: not quite enoughKarmen II Experiment: not quite enough
Pulse 800 MeV proton beam (ISIS) 17.6 m baseline 56 tons of liquid scintillator Factor of 7 less statistical reach than
LSND -> NO SIGNAL Combined analysis still leaves an
allowed region
Combined
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Role of MiniBooNERole of MiniBooNE
Boo(ster) N(eutrino) E(xperiment) Full “BooNE” would have two detectors
Primary Motivation: Absolutely confirm or refute LSND result Optimized for L/E ~ 1 Higher energy beam -> Different systematics than LSND
• E: ~30 MeV -> 500 MeV• L: ~30 m -> 500 m
Timeline Proposed: 12/97 Approved 1998 Began Construction: 10/99 Completed: 5/02 First Beam: 8/02 Began to run concurrently with NuMI: 3/05 Oscillation results: 4/07
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MiniBooNE Neutrino Beam (not to scale)MiniBooNE Neutrino Beam (not to scale)
8 GeV Protons ~ 8E16 p/hr max ~ 1 detected neutrino/minute L/E ~ 1
FNALBooster Be
Targetand Horn
“Little Muon Counter” (LMC): to understand K flux
50 m Decay Region
500m dirt
Detector
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DetectorDetector
950,000 l of pure mineral oil 1280 PMT’s in inner region 240 PMT’s outer veto region Light produced by Cerenkov radiation and
scintillation
Light barrier
Trigger:All beam spillsCosmic ray triggersLaser/pulser triggersSupernova trigger
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Neutrino Detection/Particle IDNeutrino Detection/Particle ID
e
e
n
p
W
e
e
n
p
W
n 0
Z
p 0
e
Important Background!!!
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Selecting Neutrino EventsSelecting Neutrino Events
Collect data from -5 to +15 usec around each beam spill trigger.
Identify individual “events” within this window based on PMT hits clustered in time.
Time (ns) Time (ns) Time (ns)
No cuts Veto hits < 6 Veto hits<6tank hits>200
1600 ns spill
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Delivering ProtonsDelivering Protons
Requirements of MiniBooNE greatly exceed the historical performance of the 30+ year old 8 GeV Booster, pushes… Average repetition rate Above ground radiation Radiation damage and
activation of accelerator components
Intense Program to improvethe Booster Shielding Loss monitoring and analysis Lattice improvements (result of Beam Physics involvement) Collimation system
Very challenging to continue to operate 8 GeV line during NuMI/MINOS operation Once believed impossible Element of lab’s “Proton Plan” Goal to continue to deliver roughly 2E20 protons per years to the
8 GeV program even as NuMI intensities ramp up.
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Small but HungrySmall but Hungry
MiniBooNE began taking data in Fall of 2002, and has currently taken more protons than all other users in history of Fermilab combined (including NuMI and pBar)
MiniBooNE, 86.2
All others (1974-present), 49.2
NuMI, 30.1
Total protons (1019)
63E19 Events in mode (this analysis)
In anti- mode since ~1/06
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Modeling neutrino flux Modeling neutrino flux
Production GEANT4 model of target,
horn, and beamline MARS for protons and
neutrons Sanford-Wang fit to
production data for and K Mesons allowed to decay in
model of decay pipe. Retain neutrinos which point
at target Data Constrained by HARP
Experiment
e e
K e e
K
Antineutrino content: 6% e/ = 0.5%
“Intrinsic” e + e sources: e+ e (52%)
K+ e+ e (29%)K0 e e (14%)
Other ( 5%)
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InteractionsInteractions
Cross sections Based on NUANCE 3 Monte Carlo
• Use NEUT and NEUEN as cross checks
Theoretical input:• Llewellyn-Smith free nucleon
cross sections• Rein-Sehgal resonant and
coherent cross-sections• Bodek-Yang DIS at low-Q2• Standard DIS parametrization at
high Q2• Fermi-gas model• Final state interaction model
Constraining NUANCE Observed nm data
• MAeff -- effective axial mass
• EloSF -- Pauli Blocking parameter
From electron scattering data• Eb -- binding energy• pf -- Fermi momentum
MiniBooNE
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D. Casper, NPS, 112 (2002) 161
Predicted Event Rates (NUANCE)Predicted Event Rates (NUANCE)
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Characterizing the DetectorCharacterizing the Detector
Full GEANT 3.21 model of detector Includes detailed (39-parameter!!) optical
model of oil and PMT response MC events produced at the raw data level and
reconstructed in the same way as real events
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Calibrating the DetectorCalibrating the Detector
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N 0
N
NC0
The 0 decays to 2 photons,which can look “electron-like” mimicking the signal...
<1% of 0 contribute to background.
N
N
25%
8%
CC+
Easy to tag due to 3 subevents.Not a substantial background to the oscillation analysis.
Events producing pions
(also decays to a single photon with 0.56% probability)
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Bottom line: signal and background Bottom line: signal and background
If the LSND best fit is accurate, only about a third of our observed rate will come from oscillations
Backgrounds come from both intrinsic e and misidentified
SignalMis IDIntrinsic e
Energy distribution can help separate
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Analysis PhilosophyAnalysis Philosophy
The “golden signal” in the detector is the Charged Current Quasi-Elastic (CCQE) event With a particular mass hypothesis, the neutrino energy can be reconstructed from the observed partcle with
If the LSND signal were due to neutrino oscillations, we would expect an excess in the energy range of 300-1500 MeV
The “signal” is therefore an event with A high probability of being a e CCQE event A reconstructed energy in the range 300 to 1500 MeV
cose or
eor
N N
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Two AnalysesTwo Analyses
“Track Based” analysis: Use detailed tracking information to form a particle
ID likliehood. “Box” defined by e likelihood and energy.
Backgrounds weighted by observed events outside of box.
“Boosting” Particle ID based on feeding a large amount of event
information into a “boosted decision tree” (details to follow)
“Box” defined by the boosted “score” and the mass range. Backgrounds determined by models which are largely constrained by the data.
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Common Event CutsCommon Event Cuts
>200 tank hits <6 veto hits
R<500 cm (algorithm dependent)
dataMC
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BlindnessBlindness
In general, the two analyses have sequestered (hidden) data which has A reconstructed neutrino energy in the range 300 to
1500 MeV A high probability of being an electron
This leaves the vast majority (99%) of the data available for analysis
Individual open boxes were allowed, provided it could be established that an oscillation would not lead to a significant signal.
In addition, detector level data (hit times, PMT spectra, etc) were available for all events.
Determination of “primary” analysis based on final sensitivity before opening the box
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The goal of both analyses: minimize background & maximize signal efficiency.
“Signal range” is approximately300 MeV < EQE < 1500 MeV
One can then either:• look for a total excess
(“counting expt”)• fit for both an excess and
energy dependence (“energy fit”)
MiniBooNE signal examples:m2=0.4 eV2
m2=0.7 eV2
m2=1.0 eV2
0 1 2 3 Neutrino Energy (GeV)
Arb
itra
ry U
nits
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MiniBooNE is searchingfor a small but distinctive event signature
In order to maintain blindness,Electron-like events were sequestered,Leaving ~99% of the in-beam events available for study.
Rule for cuts to sequester events: <1 signal outside of the box
Low level information which did not allow particle-idwas available for all events.
Open Data for Studies:
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Uses detailed, direct reconstruction of particle tracks,and ratio of fit likelihoods to identify particles.
Philosophy:
This algorithm was found to have the bettersensitivity to e appearance.
Therefore, before unblinding, this was the algorithm chosen for the “primary result”
Analysis 1: “Track-Based” (TB) Analysis
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Track-based analysisTrack-based analysis
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Each event is characterized by 7 reconstructed variables:
vertex (x,y,z), time, energy, and direction ()(Ux, Uy, Uz).
Resolutions: vertex: 22 cm
direction: 2.8 energy: 11%
CCQE events
2 subeventsVeto Hits<6Tank Hits>200
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Rejecting “muon-like” eventsUsing log(Le/L)
log(Le/L)>0 favors electron-like hypothesis
Note: photon conversions are electron-like.This does not separate e/0.
Separation is clean at high energies where muon-like events are long.
Analysis cut was chosento maximize the e sensitivity
e CCQE
CCQEMC
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Rejecting “0-like” events
MC
Cuts were chosen to maximize e sensitivity
Using a mass cut Using log(Le/L)
NC0
e CCQE NC0
e CCQE
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BLI
ND
eπ0
Invariant Masse π0
BLIND
Monte Carlo π0 only
Testing e-0 separation using data
1 subeventlog(Le/L)>0 (e-like)log(Le/L)<0 (-like)mass>50 (high mass)
log(Le/L)
invariant masssignal
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2 Prob for mass<50 MeV (“most signal-like”): 69%
mass<200 (low mass)log(Le/L)>0 (e-like)log(Le/L)<0 (-like)
BLIND
Monte Carlo π0 only
Next: look here....
1 subeventlog(Le/L)>0 (e-like)log(Le/L)<0 (-like)mass<200 (low mass)
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Efficiency:
Log(Le/L) + Log(Le/L) + invariant mass
Backgrounds after cuts
Summary of Track Based cuts
“Precuts” +
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Construct a set of low-level analysis variables which are used to make a series of cuts to
classify the events.
Philosophy:
This algorithm represents an independent cross check of the Track Based Analysis
Analysis 2: Boosted Decision Trees (BDT)
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Fundamental information from PMTsAnalysis Hit Position Charge Hit Timing variablesEnergy
Time sequence
Event shape
Physics
Step 1:Convert the “Fundamental information”
into “Analysis Variables”
“Physics” = 0 mass, EQE, etc.
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Resolutions:vertex: 24 cmdirection: 3.8ºenergy 14%
Examples of “Analysis Variables”
Reconstructed quantities which are inputs to EQE
CCQE CCQE
UZ = coszEvisible
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Step 2: Reduce Analysis Variables to a Single PID Variable
“A procedure that combines many weak classifiersto form a powerful committee”
Boosted Decision Trees
hit level(charge, time,
position)
analysis variables
One singlePID “score”
Byron P. Roe, et al., NIM A543 (2005) 577.
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(sequential series of cuts based on MC study)
A Decision Tree
(Nsignal/Nbkgd)
30,245/16,305
9755/23695
20455/3417 9790/12888
1906/11828 7849/11867
signal-likebkgd-like
bkgd-like sig-like
sig-like bkgd-like
etc.
This tree is one of many possibilities...
Variable 1
Variable 2
Variable 3
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A set of decision trees can be developed,each re-weighting the events to enhance identification of backgrounds misidentifiedby earlier trees (“boosting”)
For each tree, the data event is assigned +1 if it is identified as signal,-1 if it is identified as background.
The total for all trees is combined into a “score”
negative positiveBackground-
like signal-like
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BDT cuts on PID score as a function of energy.We can define a “sideband” just outside of the signal region
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BDT cuts on PID score as a function of energy.We can define a “sideband” just outside of the signal region
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BDT Efficiency and backgrounds after cuts:
Analysis cuts on PID score as a function of Energy
signal
background
Efficiency after precuts
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Errors, Constraints and Sensitivity
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We have two categories of backgrounds:
(TB analysis)
mis-id
intrinsic e
Predictions of the backgrounds are among the nine sources of significant error in the analysis
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Flux from +/+ decay 6.2 / 4.3 √ √ Flux from K+ decay 3.3 / 1.0 √ √ Flux from K0 decay 1.5 / 0.4 √ √ Target and beam models 2.8 / 1.3 √
-cross section 12.3 / 10.5 √ √ NC 0 yield 1.8 / 1.5 √
External interactions (“Dirt”) 0.8 / 3.4 √ Optical model 6.1 / 10.5 √ √ DAQ electronics model 7.5 / 10.8 √
Source of UncertaintyOn e background
Checked or Constrained by MB data
Furtherreduced by
tyinge to
Track Based/Boosted Decision Treeerror in %
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Tying the e background and signal predictionto the flux constrains this analysis to a strict
e appearance-only search
Data/MC Boosted Decision Tree: 1.22 ± 0.29 Track Based: 1.32 ± 0.26
BDT
Predict
Normalization& energy dependenceof both backgroundand signal
From the CCQE
events
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e e
• Measure the flux• Kinematics allows
connection to the flux
E(GeV)
E(GeV)
E = 0.43 E
• Once the flux is known, the flux is determined
constraint on intrinsic e from + decay chains
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K+ and K0 decay backgrounds
At high energies, above “signal range” and “e -like” events arelargely due to kaon decay
Signal examples:m2=0.4 eV2
m2=0.7 eV2
m2=1.0 eV2
Predicted rangeof significant oscillation signal:300<EQE<1500 MeV
0 1 2 3 Neutrino Energy (GeV)
Arb
itra
ry U
nitssignal
range
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TB
In Boosted DecisionTree analysis:Low energy bin (200<EQE<300 MeV)
constrains mis-ids:0, N, dirt ...
signal range
signal
up to 3000 MeV
BDT
In both analyses,high energy bins constrain
e background
Use of low-signal/high-background energy bins
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We constrain 0 production using data from our detector
Because this constrains the resonance rate, it also constrains the rate of N
Reweighting improvesagreement in other
variables, e.g.
This reduces the erroron predictedmis-identified 0s
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Other Single Photon Sources
From Efrosinin, hep-ph/0609169, calculation checked by Goldman, LANL
Neutral Current: + N + N +
Charged Current
+ N + N’ +
negligible
where the presence of the leads to mis-identification
Use events where the is tagged by the michel e-,
study misidentification using BDT algorithm.
< 6 events @ 95% CL
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“Dirt” Events
Event Type of Dirt after PID cutsEnhancedBackgroundCuts
interactions outside of the detector Ndata/NMC = 0.99 ± 0.15
Cosmic Rays: Measured from out-of-beam data: 2.1 ± 0.5 events
External Sources of Background
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Summary of predicted backgrounds forthe final MiniBooNE result(Track Based Analysis):
(example signal)
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Handling uncertainties in the analyses:
For a given source of uncertainty,
Errors on a wide rangeof parameters
in the underlying model
For a given source of uncertainty,
Errors in bins of EQE
and information on the correlationsbetween bins
What we begin with... ... what we need
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How the constraints enter...
TB: Reweight MC prediction to match measured result (accounting for systematic error correlations)
Two Approaches
Systematic (and statistical) uncertainties are included in (Mij)-1
BDT: include the correlations of to e in the error matrix:
(i,j are bins of EQE)
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MAQE, elo
sf 6%, 2% (stat + bkg only) QE norm 10% QE shape function of Ee/ QE function of E
NC 0 rate function of 0 mom MA
coh, coh ±25% Nrate function of mom + 7% BF
EB, pF 9 MeV, 30 MeVs 10% MA
1 25% MA
N 40% DIS 25%
determined fromMiniBooNE QE data
determined fromMiniBooNE NC 0 data
Example: Cross Section Uncertainties
determined from other experiments
(Many are common to and e and cancel in the fit)
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Example:Optical Model Uncertainties
39 parameters must be varied
Allowed variations are set by the Michel calibration sample
To understand allowed variations,we ran 70 hit-level simulations, with differing parameters.
“Multisims”
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Using Multisims to convert from errors on parameters to errors in EQE bins:
For each error source,“Multisims” are generated within the allowed variations
by reweighting the standard Monte Carlo.In the case of the OM, hit-level simulations are used.
number of multisims
Number of events passing cuts in bin 500<EQE<600 MeV
1000 multisims forK+ production
70 multisims for the Optical Model
standard MC
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Correlations between EQE bins from
the optical model:
• N is number of events passing cuts •MC is standard monte carlo• represents a given multisim• M is the total number of multisims• i,j are EQE bins
Error Matrix Elements:
Total error matrixis sum from each source.
TB: e-only total error matrixBDT: -e total error matrix
CVjj
MCViiij NNNN
ME
1
1 MC MC
BDT
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As we show distributions in EQE,keep in mind that error bars are
the diagonals of the error matrix.
The effect of correlations between EQE binsis not shown,
however EQE bin-to-bin correlations improve the sensitivity to oscillations,
which are based on an energy-dependent fit.
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Sensitivity of the two analyses
The Track-based sensitivity is better,thus this becomes the pre-determined default algorithm
Set using2=1.64 @ 90% CL
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Comparison to sensitivity goal for 5E20 POTdetermined by Fermilab PAC in 2003
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The Initial Results
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Box Opening Procedure
After applying all analysis cuts:
1. Fit sequestered data to an oscillation hypothesis, returning no fit parameters.Return the 2 of the data/MC comparison for a set of diagnostic variables.
2. Open up the plots from step 1. The Monte Carlo has unreported signal.Plots chosen to be useful diagnostics, without indicating if signal was added.
3. Report the 2 for a fit to EQE , without returning fit parameters.
4. Compare EQE in data and Monte Carlo, returning the fit parameters.At this point, the box is open (March 26, 2007)
5. Present results two weeks later.
Progress cautiously, in a
step-wise fashion
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Step 1
Return the 2 of the data/MC comparison for a set of diagnostic variables
All analysis variables were returned with good probability except...
Track Based analysis 2 Probability of Evisible fit: 1%
This probability was sufficiently low to merit further consideration
12 variables are tested for TB46 variables are tested for BDT
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In the Track Based analysis
• We re-examined our background estimatesusing sideband studies.
We found no evidence of a problem
• However, knowing that backgrounds rise at low energy,We tightened the cuts for the oscillation fit:
EQE> 475 MeV
We agreed to report events over the original full range: EQE> 300 MeV,
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Step 1: again!
Return the 2 of the data/MC comparison for a set of diagnostic variables
Parameters of the oscillation fit were not returned.
TB (EQE>475 MeV)BDT
2 probabilities returned:
12 variables 46 variables
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Open up the plots from step 1 for approval.
Examples ofwhat we saw:
MC contains fitted signal at unknown level
Step 2
Evisible
TB (EQE>475 MeV) BDT
fitted energy (MeV)
Evisible
2 Prob= 28%
2 Prob= 59%
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Report the 2 for a fit to EQE across full energy range
TB (EQE>475 MeV) 2 Probability of fit: 99% BDT analysis 2 Probability of fit: 52%
Step 3
Leading to...
Open the box...
Step 4
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Counting Experiment: 475<EQE<1250 MeV
data: 380 eventsexpectation: 358 19 (stat) 35 (sys) events
significance: 0.55
The Track-based e Appearance-only Result:
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Error bars arediagnonals oferror matrix.
Fit errors for >475 MeV:Normalization 9.6%Energy scale: 2.3%
Best Fit (dashed): (sin22, m2) = (0.001, 4 eV2)
Track Based energy dependent fit results:Data are in good agreement with background prediction.
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The result of the e appearance-only analysis
is a limit on oscillations:
Energy fit: 475<EQE<3000 MeV
2 probability, null hypothesis: 93%
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96 ± 17 ± 20 eventsabove background,for 300<EQE<475MeV
Deviation: 3.7
As planned before opening the box....Report the full range: 300<EQE<3000 MeV
to E>475 MeV
Background-subtracted:
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Best Fit (dashed): (sin22, m2) = (1.0, 0.03 eV2)2 Probability: 18%
Fit to the > 300 MeV range:
}Examples in LSND allowedrange
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This will be addressed by MiniBooNE and SciBooNE
This is interesting, but requires further investigation
A two-neutrino appearance-only model systematically disagrees with the shape as a function of energy.
We need to investigate non-oscillation explanations, including unexpected behavior of low energy cross sections.This will be relevant to future e searches
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Boosted Decision Tree Analysis
Counting Experiment: 300<EQE<1600 MeV data: 971 eventsexpectation: 1070 33 (stat) 225 (sys) events
significance: 0.38
HEP Seminar, UT Austin, April 30th, 2007 – E. Prebys 85
Boosted Decision Tree EQE data/MC comparison:
error bars arestat and sys(diagonals of matrix)
data -predicted (no osc) error
(sidebands used for constraint not shown)
HEP Seminar, UT Austin, April 30th, 2007 – E. Prebys 86
Boosted Decision Tree analysis shows no evidence for e appearance-only oscillations.
Energy-fit analysis:solid: TBdashed: BDT
Independent analysesare in good agreement.
HEP Seminar, UT Austin, April 30th, 2007 – E. Prebys 87
1) There are various waysto present limits:
• Single sided raster scan(historically used, presented here)
• Global scan• Unified approach
(most recent method)
2) This result must befolded into an LSND-Karmenjoint analysis.
We will present a full joint analysis soon.
Two points on interpreting our limit
Church, et al., PRD 66, 013001
HEP Seminar, UT Austin, April 30th, 2007 – E. Prebys 88
A MiniBooNE-LSND Compatibility Test
• For each m2, determine the MB and LSND measurement:
zMB zMB, zLSND zLSND where z = sin2(2) and z is the 1 error
• For each m2, form 2 between MB and LSND measurement
• Find z0 that minimizes 2
(weighted average of two measurements) and this gives 2min
• Find probability of 2min for 1 dof;
this is the joint compatibility probability for this m2
HEP Seminar, UT Austin, April 30th, 2007 – E. Prebys 89
0.001
0.010
0.100
0.25 0.75 1.25 1.75 2.25 2.75
dm2 (eV2)
Jo
int
MB
-LS
ND
Pro
b (
1d
of)
2% Compatibility
Max
imum
Joi
nt P
roba
bili
ty
m2 (eV2)
MiniBooNE is incompatible with a e appearance only interpretation of LSND
at 98% CL
HEP Seminar, UT Austin, April 30th, 2007 – E. Prebys 90
Plans:
A paper on this analysis will be posted to the “archive” and to the MiniBooNE webpage after 5 CT today.
Many more papers supporting this analysis will follow, in the very near future:
CCQE production0 productionMiniBooNE-LSND-Karmen joint analysis
We are pursuing further analyses of the neutrino data,including...
an analysis which combines TB and BDT,more exotic models for the LSND effect.
MiniBooNE is presently taking data in antineutrino mode.
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Conclusions
HEP Seminar, UT Austin, April 30th, 2007 – E. Prebys 92
• A generic search for a e excess in our beam,
• An analysis of the data within a e appearance-only context
Our goals for this first analysis were:
HEP Seminar, UT Austin, April 30th, 2007 – E. Prebys 93
Within the energy range defined by this oscillation analysis, the event rate is consistent with background.
The observed low energy deviation is under investigation.
HEP Seminar, UT Austin, April 30th, 2007 – E. Prebys 94
The observed reconstructed energy distribution is inconsistent with a e appearance-only model
Therefore we set a limit on e appearance
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We Thank:
DOE and NSF
The Fermilab Divisions and Staff
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Conclusions and OutlookConclusions and Outlook
MiniBooNE has been running for over three years, and continues to run well in the NuMI era
The analysis tools are well developed and being refined to achieve the quality necessary to release the result of our blind analysis
Recent results for CCQE and CCPiP give us confidence on our understanding of the detector and data.
Look forward to many interesting results in 2006
Backup SlidesBackup Slides
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Sterile Neutrinos: Astrophysics Constraints (courtesy M. Sterile Neutrinos: Astrophysics Constraints (courtesy M. Shaevitz)Shaevitz)
Constraints on the number of neutrinos from BBN and CMB Standard model gives
N=2.6±0.4 constraint
If 4He systematics larger, then N=4.0±2.5
If neutrino lepton asymmetry or non-equilibrium, then the BBN limit can be evaded.K. Abazajian hep-ph/0307266G. Steigman hep-ph/0309347
“One result of this is that the LSND result is not yet ruled out by cosmological observations.” Hannestad astro-ph/0303076
Bounds on the neutrino masses also depend on the number of neutrinos (active and sterile) Allowed mi is 1.4 (2.5) eV
4 (5) neutrinos
N=3 solid 4 dotted 5 dashed
Hannestad astro-ph/0303076
0.00 0.005 0.01 0.015 0.02 0.025 0.03
HEP Seminar, UT Austin, April 30th, 2007 – E. Prebys 99
Reactor Experimental ResultsReactor Experimental Results
Single reactor experiments (Chooz, Bugey, etc). Look for e disappearance: all negative
KamLAND (single scintillator detector looking at ALL Japanese reactors): e disappearance consistent with mixing.
HEP Seminar, UT Austin, April 30th, 2007 – E. Prebys 100
K2KK2K
First “long baseline” accelerator experiment Beam from KEK PS to Kamiokande, 250 km away Look for disappearance (atmospheric “problem”)
Results consistent with mixing
Best fit
No mixing
Allowed Mixing Region
HEP Seminar, UT Austin, April 30th, 2007 – E. Prebys 101
HARP (CERN) 5% Beryllium target 8.9 GeV proton beam momentum
Modeling Production of Secondary Pions
HARP collaboration,hep-ex/0702024
Data are fit to a Sanford-Wangparameterization.
HEP Seminar, UT Austin, April 30th, 2007 – E. Prebys 102
Everybody Loves a MysteryEverybody Loves a Mystery
3+2 Sterile neutrinos Sorel, Conrad, and Shaevitz (hep-ph/0305255)
MaVaN & 3+1 Hung (hep-ph/0010126)
Sterile neutrinos Kaplan, Nelson, and Weiner (hep-ph/0401099)
• Explain Dark Energy? CPT violation and 3+1 neutrinos
Barger, Marfatia & Whisnant (hep-ph/0308299)• Explain matter/antimatter asymmetry
Lorentz Violation Kostelecky & Mewes (hep-ph/0406035)
Extra Dimensions Pas, Pakvasa, & Weiler (hep-ph/0504096)
Sterile Neutrino Decay Palomares-Ruiz, Pascoli & Schwetz (hep-ph/0505216)
HEP Seminar, UT Austin, April 30th, 2007 – E. Prebys 103
Three Generation Mixing (Driven by experiments listed)Three Generation Mixing (Driven by experiments listed)
General Mixing Parameterization
231312231312231223131223
231312231312231223131223
1312131213
ccescscseccsss
scesssccecsssc
essccc
ii
ii
i
CP violating phase
Almost diagonal Third generation weakly
coupled to first two “Wolfenstein Parameterization”
Mixing large No easy simplification Think of mass and weak eigenstates as totally separate
HEP Seminar, UT Austin, April 30th, 2007 – E. Prebys 104
SNO Solar Neutrino ResultSNO Solar Neutrino Result
Looked for Cerenkov signals in a large detector filled with heavy water. Focus on 8B neutrinos Used 3 reactions:
e+dp+p+e-: only sensitive to e
x+dp+n+x: equally sensitive to e , , x+ e- x+ e-: 6 times more sensitive to e than ,d
Consistent with initial full SSM flux of e’s mixing to , Completely consistent with three generation mixing
Just SNO SNO+others
34.tan;eV105 :Favor 2252 Δm