MiniBooNE
description
Transcript of MiniBooNE
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MiniBooNEMiniBooNE
• MiniBooNE Motivation• LSND Signal
• Interpreting the LSND Signal
• MiniBooNE Overview• Experimental Setup
• Neutrino Events in the Detector
• The Oscillation Search
• Studying MiniBooNE Hadron Production at HARP• The HARP Data Set
• HARP Analysis
Outline
Vth Rencontres du Vietnam 2004David Schmitz
Columbia University
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Vth Rencontres du Vietnam – 07 August, 2004 David Schmitz – Columbia University 2
MiniBooNE Motivation : The LSND Result• The Liquid Scintillator Neutrino Detector was the first accelerator based neutrino oscillation experiment to see a signal.
• LSND saw a 3.8 excess (above expected background) of e in a beam.
)%045.0067.0264.0()(Prob e
• The KARMEN experiment was a similar experiment that saw no signal neutrinos. KARMEN had less statistics and a slightly different experimental L/E.
•A combined analysis of LSND and KARMEN leaves a substantial allowed region.
combined analysis allowed region
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Vth Rencontres du Vietnam – 07 August, 2004 David Schmitz – Columbia University 3
MiniBooNE Motivation : Interpreting the LSND Signal
m13
m12
m23
m13
m12
m23
• What to make of 3 independent m2 values?• solar exp. (Super-K, K, SNO, KamLAND, …)
m2 ~ 10-5 eV2
• atmospheric exp. (Super-K, K, …) m2 ~ 10-3 eV2
• accelerator exp. (LSND) m2 ~ 1 eV2
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Vth Rencontres du Vietnam – 07 August, 2004 David Schmitz – Columbia University 4
MiniBooNE Motivation : Interpreting the LSND Signal
• What to make of 3 independent m2 values?• solar exp. (Super-K, K, SNO, KamLAND, …)
m2 ~ 10-5 eV2
• atmospheric exp. (Super-K, K, …) m2 ~ 10-3 eV2
• accelerator exp. (LSND) m2 ~ 1 eV2
m13
m12
m23
• One of the experimental results is incorrect. Must verify each m2.
• atmospheric and solar results are well confirmed.
• accelerator and reactor based exp. in the atmo. and solar ranges (K2K, MINOS, KamLAND)
• LSND requires confirmation.
m13
m12
m23
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Vth Rencontres du Vietnam – 07 August, 2004 David Schmitz – Columbia University 5
MiniBooNE Motivation : Interpreting the LSND Signal
m13
m12
m23
m13
m12
m23
• What to make of 3 independent m2 values?• solar exp. (Super-K, K, SNO, KamLAND, …)
m2 ~ 10-5 eV2
• atmospheric exp. (Super-K, K, …) m2 ~ 10-3 eV2
• accelerator exp. (LSND) m2 ~ 1 eV2
• Addition of 1 or more “Sterile” neutrinos to the 3 neutrino standard model.
• LSND could be explained by oscillations to sterile neutrinos.
• One of the experimental results is incorrect. Must verify each m2.
• atmospheric and solar results are well confirmed.
• accelerator and reactor based exp. in the atmo. and solar ranges (K2K, MINOS, KamLAND)
• LSND requires confirmation.
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Vth Rencontres du Vietnam – 07 August, 2004 David Schmitz – Columbia University 6
MiniBooNE Motivation : Interpreting the LSND Signal
• What to make of 3 independent m2 values?• solar exp. (Super-K, K, SNO, KamLAND, …)
m2 ~ 10-5 eV2
• atmospheric exp. (Super-K, K, …) m2 ~ 10-3 eV2
• accelerator exp. (LSND) m2 ~ 1 eV2
• Other possibilities• CPT violation
• CP violation + sterile neutrinos
• others…
?
• One of the experimental results is incorrect. Must verify each m2.
• atmospheric and solar results are well confirmed.
• accelerator and reactor based exp. in the atmo. and solar ranges (K2K, MINOS, KamLAND)
• LSND requires confirmation.
• Addition of 1 or more “Sterile” neutrinos to the 3 neutrino standard model.
• LSND could be explained by oscillations to sterile neutrinos.
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Vth Rencontres du Vietnam – 07 August, 2004 David Schmitz – Columbia University 7
MiniBooNE Motivation : Interpreting the LSND Signal
• What to make of 3 independent m2 values?• solar exp. (Super-K, K, SNO, KamLAND, …)
m2 ~ 10-5 eV2
• atmospheric exp. (Super-K, K, …) m2 ~ 10-3 eV2
• accelerator exp. (LSND) m2 ~ 1 eV2
• Other possibilities• CPT violation
• CP violation + sterile neutrinos
• others…
• One of the experimental results is incorrect. Must verify each m2.
• atmospheric and solar results are well confirmed.
• accelerator and reactor based exp. in the atmo. and solar ranges (K2K, MINOS, KamLAND)
• LSND requires confirmation.
• Addition of 1 or more “Sterile” neutrinos to the 3 neutrino standard model.
• LSND could be explained by oscillations to sterile neutrinos.
The LSND signal must be confirmed or ruled out to know how to proceed in the neutrino sector.
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Vth Rencontres du Vietnam – 07 August, 2004 David Schmitz – Columbia University 8
MiniBooNE Overview : Experimental Setup
• MiniBooNE receives 8.9 GeV/c protons from the Fermilab Booster.
• Protons are focused onto a 1.7 interaction length beryllium target producing various secondaries (p’s, ’s, K’s).
• Secondaries are focused via a magnetic focusing horn surrounding the target. The horn receives 170 kA pulses at up to 10 Hz.
Decay region
25 m50 m 450 m
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Vth Rencontres du Vietnam – 07 August, 2004 David Schmitz – Columbia University 9
MiniBooNE Overview : Experimental Setup
• Secondary mesons (’s, K’s) decay in the 50m decay region to produce the MiniBooNE neutrino beam.
• A removable 25m absorber can be inserted. A great advantage for studying backgrounds.
• The horn is capable of running with the polarity reversed…anti-neutrino mode.
Decay region
25 m50 m 450 m
e
0
0
0
0
K
eK
eK
K
K
e
e
e
( )
( )
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Vth Rencontres du Vietnam – 07 August, 2004 David Schmitz – Columbia University 10
MiniBooNE Overview : Experimental Setup
• Neutrinos are detected ~500 m away in a 12 m diameter Čerenkov detector.
• 950,000 liters of mineral oil
• 1280 photomultiplier tubes
• 240 optically isolated veto tubes
Decay region
25 m50 m 450 m
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MiniBooNE Overview : Neutrinos in the Detector
• We look for remnants of CC events in the detector producing a ring of prompt Čerenkov light and a small amount of delayed scintillation light.
epne
0
l
pZ 0
• NC 0 events are characterized by the double rings produced by 0 . These events can look like electron events when the photons overlap or the decay is asymmetric.
pn
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MiniBooNE Overview : More About CCQE Events
• Reconstruct the lepton angle with respect to the beam direction.
• Measure visible energy from Čerenkov light and small amount of scintillation light.
• ~10% E resolution at 1GeV with no background
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MiniBooNE Overview : More About CCQE Events
ell
llQE
PEMmMEE
cos2
21 2
CCQE Event Reconstruction
• Reconstruct the lepton angle with respect to the beam direction.
• Measure visible energy from Čerenkov light and small amount of scintillation light.
• ~10% E resolution at 1GeV with no background
PRELIMINARY PRELIMINARY PRELIMINARY
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MiniBooNE Overview : eOscillation Sensitivity
• Recall that the MiniBooNE e appearance analysis is a blind analysis.
• eCCQE events suffer from larger backgrounds than events.
• Use measurements both internal and external to constrain background rates.
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Vth Rencontres du Vietnam – 07 August, 2004 David Schmitz – Columbia University 15
MiniBooNE Overview : eOscillation Sensitivity
• Recall that the MiniBooNE e appearance analysis is a blind analysis.
• eCCQE events suffer from larger backgrounds than events.
• Use measurements both internal and external to constrain background rates.
• With 1x1021 protons on target
• Average ~5% uncertainty on background rates.
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Vth Rencontres du Vietnam – 07 August, 2004 David Schmitz – Columbia University 16
MiniBooNE Overview : eOscillation Sensitivity
• Recall that the MiniBooNE e appearance analysis is a blind analysis.
• eCCQE events suffer from larger backgrounds than events.
• Use measurements both internal and external to constrain background rates.
• With 1x1021 protons on target
• Average ~5% uncertainty on background rates.
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Vth Rencontres du Vietnam – 07 August, 2004 David Schmitz – Columbia University 17
m2 = 0.4 eV2
m2 = 1 eV2
MiniBooNE Overview : eOscillation Signal
SignalMis IDIntrinsic e
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MiniBooNE Beam : Hadron Production at HARP
• The first goal is to measure + production cross sections for Be at pproton = 8.9 GeV/c.
• Additional measurements include:• - production (important for running)
• K production (important for intrinsic e backgrounds)
MiniBooNE has cooperated with the HARP experiment (PS-214) at CERN to measure hadron production from the MiniBooNE beryllium target.
No target 1.1 M events Normalization
5% Be 7.3 M events p+Be x-section
50% MB replica 5.4 M events Effects specific to MB target
reinteraction absorptionscattering100% MB replica 6.4 M events
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MiniBooNE Beam : Beryllium Target• The MB target is ~71 cm long and 1 cm in diameter
• Cooling fins (also Be)
• Comprised of seven ~10 cm slugs
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HARP : Cross Section Measurement
jj
jijtrack
iacci
i NM 111
truep ),( recp ),( pion purity
pion yieldtracking efficiency
migration matrixacceptance
pion efficiency
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Vth Rencontres du Vietnam – 07 August, 2004 David Schmitz – Columbia University 21
HARP : Cross Section Measurement
jj
jijtrack
iacci
i NM 111
truep ),( recp ),( pion purity
pion yieldtracking efficiency
migration matrixacceptance
pion efficiency
• Acceptance is determined using the MC (compare to MB requirements)
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Vth Rencontres du Vietnam – 07 August, 2004 David Schmitz – Columbia University 22
HARP : Cross Section Measurement
jj
jijtrack
iacci
i NM 111
truep ),( recp ),( pion purity
pion yieldtracking efficiency
migration matrixacceptance
pion efficiency
• Acceptance is determined using the MC (compare to MB requirements)
• Tracking Efficiency and Migration (no time to discuss today).
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Vth Rencontres du Vietnam – 07 August, 2004 David Schmitz – Columbia University 23
HARP : Cross Section Measurement
jj
jijtrack
iacci
i NM 111
truep ),( recp ),( pion purity
pion yieldtracking efficiency
migration matrixacceptance
pion efficiency
• Acceptance is determined using the MC (compare to MB requirements)
• Tracking Efficiency and Migration (no time to discuss today).
• Raw Particle Yields and Efficiency and Purity of the selection.
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MiniBooNE Beam : Relevant Phase SpaceMomentum distribution peaks at ~1.5 GeV/c and trails off at 6 GeV/c.
Angular distribution of pions is mostly below 200 mrad.
Momentum and Angular distribution of pions decaying to a neutrino that passes through the MB detector.
Acceptance of HARP forward detector
Acceptance in P for |y|<50 mrad & |x|<200 mrad
Acceptance in x for |y|<50 mrad & P > 1 GeV
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HARP Detector : Overlapping PID Detectors0 1 2 3 4 5 6 7 8 9 10
pP (GeV)
ek
TOFCERENKOV
TOF ?CERENKOV
CERENKOVCALORIMETER
TOF
CERENKOV
CAL
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Vth Rencontres du Vietnam – 07 August, 2004 David Schmitz – Columbia University 26
HARP Detector : Overlapping PID Detectors0 1 2 3 4 5 6 7 8 9 10
pP (GeV)
ek
TOFCERENKOV
TOF ?CERENKOV
CERENKOVCALORIMETER
TOF
CERENKOV
CAL
),,,,|( 21 EENpP pe
2 plane Calin deposited1 plane Calin deposited
)/(*
1
momentum tedreconstruc
2
1
2
EE
LLNN
Ltc
p
pathckovpepe
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Vth Rencontres du Vietnam – 07 August, 2004 David Schmitz – Columbia University 27
HARP Detector : Overlapping PID Detectors0 1 2 3 4 5 6 7 8 9 10
pP (GeV)
ek
TOFCERENKOV
TOF ?CERENKOV
CERENKOVCALORIMETER
TOF
CERENKOV
CAL
),,,,|( 21 EENpP pe
)()|(
)()|()|(BPBAPBPBAPABP ii
i
,...,,,
},,,,{ 21
KepB
EENpA pe
Bayes Theorem
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Vth Rencontres du Vietnam – 07 August, 2004 David Schmitz – Columbia University 28
HARP Detector : Overlapping PID Detectors
eKppe
pepe pPpEEPpNPpP
pPpEEPpNPpPEENpP
,,,21
2121 )|(),|,(),|(),|(
)|(),|,(),|(),|( ),,,,|(
tof cerenkov calorimetermomentumdistribution
0 1 2 3 4 5 6 7 8 9 10
pP (GeV)
ek
TOFCERENKOV
TOF ?CERENKOV
CERENKOVCALORIMETER
TOF
CERENKOV
CAL
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Vth Rencontres du Vietnam – 07 August, 2004 David Schmitz – Columbia University 29
Pion ID : Beam Particles• Use no target runs to determine correction factor for PID. Beam detector ID is considered “true” ID.
• PID Input (for 1st iteration) is found from crude cuts on detector data. But method is quite insensitive to starting input.
• Need MC to determine efficiency and purity for continuous p,
PRELIMINARY PRELIMINARY PRELIMINARY
jj
j 1
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Vth Rencontres du Vietnam – 07 August, 2004 David Schmitz – Columbia University 30
Pion ID : Beryllium 5% Target
• Run iterative PID algorithm on Be 5% target data to extract raw pion yields.
• PID efficiency and purity determined using no target data (MC).
• Tracking efficiency determined using both data and MC.
• Acceptance determined from the MC.
PRELIMINARY PRELIMINARY
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Vth Rencontres du Vietnam – 07 August, 2004 David Schmitz – Columbia University 31
Next Steps• Continue to improve particle probability functions for the three detectors using data and MC.
• Implement tracking, PID, and acceptance corrections to raw particle yields.
• Move towards normalized pion cross section measurement.
Next Next Steps• Study pion absorption and reinteraction effects in the thick target by
using data from three different target lengths.
• How well can we do /K separation?
• Finally, generate neutrino fluxes for MiniBooNE using measurements from HARP.