MiniBooNE 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 V th Rencontres du Vietnam 2004 David Schmitz Columbia University

V th Rencontres du Vietnam – 07 August, 2004David Schmitz – Columbia University2 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. 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

V th Rencontres du Vietnam – 07 August, 2004David Schmitz – Columbia University3 MiniBooNE Motivation : Interpreting the LSND Signal What to make of 3 independent  m 2 values? solar exp. (Super-K, K, SNO, KamLAND, …)  m 2 ~ eV 2 atmospheric exp. (Super-K, K, …)  m 2 ~ eV 2 accelerator exp. (LSND)  m 2 ~ 1 eV 2

V th Rencontres du Vietnam – 07 August, 2004David Schmitz – Columbia University4 MiniBooNE Motivation : Interpreting the LSND Signal What to make of 3 independent  m 2 values? solar exp. (Super-K, K, SNO, KamLAND, …)  m 2 ~ eV 2 atmospheric exp. (Super-K, K, …)  m 2 ~ eV 2 accelerator exp. (LSND)  m 2 ~ 1 eV 2 One of the experimental results is incorrect. Must verify each  m 2. atmospheric and solar results are well confirmed. accelerator and reactor based exp. in the atmo. and solar ranges (K2K, MINOS, KamLAND) LSND requires confirmation.

V th Rencontres du Vietnam – 07 August, 2004David Schmitz – Columbia University5 MiniBooNE Motivation : Interpreting the LSND Signal What to make of 3 independent  m 2 values? solar exp. (Super-K, K, SNO, KamLAND, …)  m 2 ~ eV 2 atmospheric exp. (Super-K, K, …)  m 2 ~ eV 2 accelerator exp. (LSND)  m 2 ~ 1 eV 2 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  m 2. atmospheric and solar results are well confirmed. accelerator and reactor based exp. in the atmo. and solar ranges (K2K, MINOS, KamLAND) LSND requires confirmation.

V th Rencontres du Vietnam – 07 August, 2004David Schmitz – Columbia University6 MiniBooNE Motivation : Interpreting the LSND Signal What to make of 3 independent  m 2 values? solar exp. (Super-K, K, SNO, KamLAND, …)  m 2 ~ eV 2 atmospheric exp. (Super-K, K, …)  m 2 ~ eV 2 accelerator exp. (LSND)  m 2 ~ 1 eV 2 Other possibilities CPT violation CP violation + sterile neutrinos others… ? One of the experimental results is incorrect. Must verify each  m 2. 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.

V th Rencontres du Vietnam – 07 August, 2004David Schmitz – Columbia University7 MiniBooNE Motivation : Interpreting the LSND Signal What to make of 3 independent  m 2 values? solar exp. (Super-K, K, SNO, KamLAND, …)  m 2 ~ eV 2 atmospheric exp. (Super-K, K, …)  m 2 ~ eV 2 accelerator exp. (LSND)  m 2 ~ 1 eV 2 Other possibilities CPT violation CP violation + sterile neutrinos others… One of the experimental results is incorrect. Must verify each  m 2. 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.

V th Rencontres du Vietnam – 07 August, 2004David Schmitz – Columbia University8 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 m 50 m450 m

V th Rencontres du Vietnam – 07 August, 2004David Schmitz – Columbia University9 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 m 50 m450 m ( )

V th Rencontres du Vietnam – 07 August, 2004David Schmitz – Columbia University10 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 m 50 m450 m

V th Rencontres du Vietnam – 07 August, 2004David Schmitz – Columbia University11 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. 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.

V th Rencontres du Vietnam – 07 August, 2004David Schmitz – Columbia University12 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

V th Rencontres du Vietnam – 07 August, 2004David Schmitz – Columbia University13 MiniBooNE Overview : More About CCQE Events  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

V th Rencontres du Vietnam – 07 August, 2004David Schmitz – Columbia University14 MiniBooNE Overview :  e  Oscillation Sensitivity Recall that the MiniBooNE e appearance analysis is a blind analysis. e  CCQE events suffer from larger backgrounds than  events. Use measurements both internal and external to constrain background rates.

V th Rencontres du Vietnam – 07 August, 2004David Schmitz – Columbia University15 MiniBooNE Overview :  e  Oscillation Sensitivity Recall that the MiniBooNE e appearance analysis is a blind analysis. e  CCQE events suffer from larger backgrounds than  events. Use measurements both internal and external to constrain background rates. With 1x10 21 protons on target Average ~5% uncertainty on background rates.

V th Rencontres du Vietnam – 07 August, 2004David Schmitz – Columbia University16 MiniBooNE Overview :  e  Oscillation Sensitivity Recall that the MiniBooNE e appearance analysis is a blind analysis. e  CCQE events suffer from larger backgrounds than  events. Use measurements both internal and external to constrain background rates. With 1x10 21 protons on target Average ~5% uncertainty on background rates.

V th Rencontres du Vietnam – 07 August, 2004David Schmitz – Columbia University17  m 2 = 0.4 eV 2  m 2 = 1 eV 2 MiniBooNE Overview :  e  Oscillation Signal Signal Mis ID Intrinsic e

V th Rencontres du Vietnam – 07 August, 2004David Schmitz – Columbia University18 MiniBooNE Beam : Hadron Production at HARP The first goal is to measure  + production cross sections for Be at p proton = 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 target1.1 M eventsNormalization 5% Be 7.3 M eventsp+Be x-section 50% MB replica 5.4 M eventsEffects specific to MB target reinteraction absorption scattering 100% MB replica 6.4 M events

V th Rencontres du Vietnam – 07 August, 2004David Schmitz – Columbia University19 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

V th Rencontres du Vietnam – 07 August, 2004David Schmitz – Columbia University20 HARP : Cross Section Measurement pion purity pion yield tracking efficiency migration matrixacceptance pion efficiency

V th Rencontres du Vietnam – 07 August, 2004David Schmitz – Columbia University21 HARP : Cross Section Measurement pion purity pion yield tracking efficiency migration matrixacceptance pion efficiency Acceptance is determined using the MC (compare to MB requirements)

V th Rencontres du Vietnam – 07 August, 2004David Schmitz – Columbia University22 HARP : Cross Section Measurement pion purity pion yield tracking efficiency migration matrixacceptance pion efficiency Acceptance is determined using the MC (compare to MB requirements) Tracking Efficiency and Migration (no time to discuss today).

V th Rencontres du Vietnam – 07 August, 2004David Schmitz – Columbia University23 HARP : Cross Section Measurement pion purity pion yield tracking 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.

V th Rencontres du Vietnam – 07 August, 2004David Schmitz – Columbia University24 MiniBooNE Beam : Relevant Phase Space Momentum 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 | 1 GeV

V th Rencontres du Vietnam – 07 August, 2004David Schmitz – Columbia University25 HARP Detector : Overlapping PID Detectors  p P (GeV)  e  k TOF CERENKOV TOF ? CERENKOV CALORIMETER TOF CERENKOV CAL

V th Rencontres du Vietnam – 07 August, 2004David Schmitz – Columbia University26 HARP Detector : Overlapping PID Detectors  p P (GeV)  e  k TOF CERENKOV TOF ? CERENKOV CALORIMETER TOF CERENKOV CAL

V th Rencontres du Vietnam – 07 August, 2004David Schmitz – Columbia University27 HARP Detector : Overlapping PID Detectors  p P (GeV)  e  k TOF CERENKOV TOF ? CERENKOV CALORIMETER TOF CERENKOV CAL Bayes Theorem

V th Rencontres du Vietnam – 07 August, 2004David Schmitz – Columbia University28 HARP Detector : Overlapping PID Detectors tof cerenkov calorimeter momentum distribution  p P (GeV)  e  k TOF CERENKOV TOF ? CERENKOV CALORIMETER TOF CERENKOV CAL

V th Rencontres du Vietnam – 07 August, 2004David Schmitz – Columbia University29 Pion ID : Beam Particles Use no target runs to determine correction factor for PID. Beam detector ID is considered “true” ID. PID Input (for 1 st 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

V th Rencontres du Vietnam – 07 August, 2004David Schmitz – Columbia University30 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

V th Rencontres du Vietnam – 07 August, 2004David Schmitz – Columbia University31 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.