# Presentation: 489835

## 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**

## 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

## MiniBooNE Motivation : Interpreting the LSND Signal

- MiniBooNE Motivation : Interpreting the LSND Signal

** ****What to make of 3 independent ********m****2**** values?**
** ****solar exp.  (Super-K, K, SNO, KamLAND, ...) ****	****   ****	********m****2**** ~ 10****-5**** eV****2**** **
** ****atmospheric exp.  (Super-K, K, ...)                                      ****	********m****2**** ~ 10****-3**** eV****2**
** ****accelerator exp.  (LSND)                                          ****	********m****2**** ~ 1 eV****2****   **

## MiniBooNE Motivation : Interpreting the LSND Signal

- MiniBooNE Motivation : Interpreting the LSND Signal

** ****What to make of 3 independent ********m****2**** values?**
** ****solar exp.  (Super-K, K, SNO, KamLAND, ...) ****	****   ****	********m****2**** ~ 10****-5**** eV****2**** **
** ****atmospheric exp.  (Super-K, K, ...)                                      ****	********m****2**** ~ 10****-3**** 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. **

## MiniBooNE Motivation : Interpreting the LSND Signal

- MiniBooNE Motivation : Interpreting the LSND Signal

** ****What to make of 3 independent ********m****2**** values?**
** ****solar exp.  (Super-K, K, SNO, KamLAND, ...) ****	****   ****	********m****2**** ~ 10****-5**** eV****2**** **
** ****atmospheric exp.  (Super-K, K, ...)                                      ****	********m****2**** ~ 10****-3**** 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. **

## MiniBooNE Motivation : Interpreting the LSND Signal

- MiniBooNE Motivation : Interpreting the LSND Signal

** ****What to make of 3 independent ********m****2**** values?**
** ****solar exp.  (Super-K, K, SNO, KamLAND, ...) ****	****   ****	********m****2**** ~ 10****-5**** eV****2**** **
** ****atmospheric exp.  (Super-K, K, ...)                                      ****	********m****2**** ~ 10****-3**** 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. **

## MiniBooNE Motivation : Interpreting the LSND Signal

- MiniBooNE Motivation : Interpreting the LSND Signal

** ****What to make of 3 independent ********m****2**** values?**
** ****solar exp.  (Super-K, K, SNO, KamLAND, ...) ****	****   ****	********m****2**** ~ 10****-5**** eV****2**** **
** ****atmospheric exp.  (Super-K, K, ...)                                      ****	********m****2**** ~ 10****-3**** 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.**

## 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 m

- 450 m

## 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 m

- 450 m

- (     )

- (    )

## 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 m

- 450 m

## MiniBooNE Overview : Neutrinos in the Detector

- 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.**

## 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**

## MiniBooNE Overview : More About CCQE Events

- 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

- PRELIMINARY

- PRELIMINARY

## 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.**

## 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.**

## 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.**

## MiniBooNE Overview : eOscillation Signal

- MiniBooNE Overview : eOscillation Signal

## 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 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  absorption
scattering |
| 100%  MB replica | 6.4 M events |  |

## 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**

## HARP : Cross Section Measurement

- pion purity

- pion yield

- tracking efficiency

- migration matrix

- acceptance

- pion efficiency

## HARP : Cross Section Measurement

- HARP : Cross Section Measurement

- pion purity

- pion yield

- tracking efficiency

- migration matrix

- acceptance

- pion efficiency

** ****Acceptance is determined using the MC (compare to MB requirements)**

## HARP : Cross Section Measurement

- HARP : Cross Section Measurement

- pion purity

- pion yield

- tracking efficiency

- migration matrix

- acceptance

- pion efficiency

** ****Acceptance is determined using the MC (compare to MB requirements)**
** ****Tracking Efficiency and Migration (no time to discuss today).**

## HARP : Cross Section Measurement

- HARP : Cross Section Measurement

- pion purity

- pion yield

- tracking efficiency

- migration matrix

- acceptance

- 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.**

## MiniBooNE Beam : Relevant Phase Space

- 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****|<50 mrad & P > 1 GeV **

## HARP Detector : Overlapping PID Detectors

- HARP Detector : Overlapping PID Detectors

**0       1      2       3      4       5      6       7       8      9      10**** **

- p

**P (GeV)**

- e

- k

***TOF***

***CERENKOV***

***TOF  ?***

***CERENKOV***

***CERENKOV***

***CALORIMETER***

***TOF***

***CERENKOV***

***CAL***

## HARP Detector : Overlapping PID Detectors

- HARP Detector : Overlapping PID Detectors

**0       1      2       3      4       5      6       7       8      9      10**** **

- p

**P (GeV)**

- e

- k

***TOF***

***CERENKOV***

***TOF  ?***

***CERENKOV***

***CERENKOV***

***CALORIMETER***

***TOF***

***CERENKOV***

***CAL***

## HARP Detector : Overlapping PID Detectors

- HARP Detector : Overlapping PID Detectors

**0       1      2       3      4       5      6       7       8      9      10**** **

- p

**P (GeV)**

- e

- k

***TOF***

***CERENKOV***

***TOF  ?***

***CERENKOV***

***CERENKOV***

***CALORIMETER***

***TOF***

***CERENKOV***

***CAL***

**Bayes Theorem**

## HARP Detector : Overlapping PID Detectors

***tof***

***cerenkov***

***calorimeter***

***momentum***
***distribution***

**0       1      2       3      4       5      6       7       8      9      10**** **

- p

**P (GeV)**

- e

- k

***TOF***

***CERENKOV***

***TOF  ?***

***CERENKOV***

***CERENKOV***

***CALORIMETER***

***TOF***

***CERENKOV***

***CAL***

## 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

- PRELIMINARY

- PRELIMINARY

## 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

## 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.**