MiniBooNE
description
Transcript of MiniBooNE
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
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
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
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
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.
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.
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.
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
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
( )
( )
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
Vth Rencontres du Vietnam – 07 August, 2004 David Schmitz – Columbia University 11
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
Vth Rencontres du Vietnam – 07 August, 2004 David Schmitz – Columbia University 12
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
Vth Rencontres du Vietnam – 07 August, 2004 David Schmitz – Columbia University 13
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
Vth Rencontres du Vietnam – 07 August, 2004 David Schmitz – Columbia University 14
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.
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.
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.
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
Vth Rencontres du Vietnam – 07 August, 2004 David Schmitz – Columbia University 18
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
Vth Rencontres du Vietnam – 07 August, 2004 David Schmitz – Columbia University 19
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
Vth Rencontres du Vietnam – 07 August, 2004 David Schmitz – Columbia University 20
HARP : Cross Section Measurement
jj
jijtrack
iacci
i NM 111
truep ),( recp ),( pion purity
pion yieldtracking efficiency
migration matrixacceptance
pion efficiency
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)
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).
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.
Vth Rencontres du Vietnam – 07 August, 2004 David Schmitz – Columbia University 24
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
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
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2
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LLNN
Ltc
p
pathckovpepe
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
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
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
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
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.