# Presentation: 268667

## Zelimir Djurcic
Columbia University

**Measurement of the off-axis NuMI beam with MiniBooNE**

**Zelimir Djurcic**
**Columbia University**

- Outline of this Presentation
- Off-axis Neutrino Beam
- NuMI flux at MiniBooNE
- MiniBooNE Detector and Reconstruction
- CC **** Sample
- NC ** Sample
- CC ***e* Sample

**Brookhaven National Lab Seminar, 1/17/08**

## Fermilab Neutrino Beams 

**Fermilab Neutrino Beams **

## MiniBooNE Motivated the LSND Experiment Result

- LSND observed a (~3.8) excess of anti-e events in a pureanti- beam:  87.9 ± 22.4 ± 6.0 events

-  Models developed with 2 sterile ’s

**MiniBooNE Motivated the LSND Experiment Result**

- In SM there are
- only 3 neutrinos

##  Result of the MiniBooNE Oscillation Search 

- MiniBooNE Data Shows Low Energy Excess!

-                              _ __reconstructed neutrino energy bin (MeV)_
- _                               __200-300           300-475       475-1250    _
- data                        375                     369             380
- _total background284 ± 25           274 ± 21     358 ± 35_
**Excess               91 ± 30       95 ± 27    22 ± 40**

** ****Result of the MiniBooNE Oscillation Search **

##  NuMI Beam 

- 	120 GeV protons ~ 3xE13/pulse.
- 	Primarily for the MINOS long baseline experiment.

- MINOS Experiment
- L~700 km
- E~2-5GeV

- However, the NuMI beam points in the direction of MiniBooNE as well.

** ****NuMI Beam **

- 

- Target

- Horns

- Decay Pipe

-  Detector

- First Proposed
- by BNL-E889

-      On-axis, neutrino energy more tightly related to hadron energy.
-      Off-axis, neutrino spectrum is narrow-band and ‘softened’.
-      Easier to estimate flux correctly:  all mesons decay to same energy  .

**Off-axis Beam **

##    Use off-axis trick for optimized ->e search.

- NuMI off-axis beam
- 810km baseline
- 14.5mrad; E~2GeV

-  T2K:
- J-PARC 50GeV proton beam
- Use SK as Far detector 295km away
- 35 mrad; E~0.6GeV

-    Use off-axis trick for optimized ->e search.

*On-axis beam*

*Off-axis beam*

**Future off-axis Neutrino Experiments **

## NuMI events (for MINOS) detected in MiniBooNE detector! 

**MiniBooNE detector is 745 meters downstream of NuMI target.**
**MiniBooNE detector is 110 mrad off-axis from ****the target **
**	****	****	****along NuMI decay pipe.**

**Decay Pipe**

*p* beam

- , *K*

**MiniBooNE**

- 

**NuMI beam and MiniBooNE detector**

## Analysis Motivation 

- Observation and analysis of an off-axis beam. Measurement of /K components of the NuMI beam.The NuMI beam provides MiniBooNE with an independent set of neutrino interactions.Enables a comparison of the Booster Neutrino Beam (BNB) with the NuMI neutrino beam (off axis):-Similar energy spectrum.-Proton target is further away (~746 m vs. 550 m)-Very different background composition.-Rich in e flux →can study e reactions in greater      detail.

## Beam Information and Neutrino Fluxes at MiniBooNE are provided by the MINOS collaboration (BNL, U Texas).

- Analysis of MiniBooNE data performed by the MiniBooNE collaboration.

**Joint collaboration between MiniBooNE and NuMI**

## 	Opportunity to demonstrate off-axis technique.

    Known spectral features from , K decays.

    Expected energy spectra is within MiniBooNE energy acceptance.

- 	Opportunity to demonstrate off-axis technique.
-     Known spectral features from , *K* decays.
-     Expected energy spectra is within MiniBooNE energy acceptance.

**NuMI off-axis beam at MiniBooNE detector**

##      NuMI off-axis beam produces strong fluxes  in both μ and e flavors. 

    The e ’s are helpful to study the MiniBooNE detector.

    Provide a new setting for oscillation studies.

  Rates:
  NuMI off-axis(at MB) e ~6%
  NuMI on-axis e ~1% 
  BNB on-axis e ~0.5%

-     The ***e* ’s are helpful to study the MiniBooNE detector.
-     Provide a new setting for oscillation studies.
-   Rates:
-   NuMI off-axis(at MB) ***e *~6%
-   NuMI on-axis ***e* ~1%
-   BNB on-axis ***e* ~0.5%

**NuMI as a “********e**** Source”**

*K*

**

- stopped *K*

## 	Extensive experience with MINOS data.
	MINOS acquired data sets in variety of NuMI configurations.
	Tuned kaon and pion production (xF,pT) to MINOS data.

- 	MINOS acquired data sets in variety of NuMI configurations.
- 	Tuned kaon and pion production (*x*F,*p*T) to MINOS data.

- MINOS ****

- MINOS ****

- 	Same parent hadrons produce neutrinos seen by MiniBooNE
- 	Flux at MiniBooNE should be well-described by NuMI beam MC?

- D.G. Michael et al, Phys. Rev. Lett. 97:191801 (2006)
- D.G. Michael et al, arXiv:0708.1495 (2007)

**NuMI Neutrino Spectrum is “Calibrated”**

##      Decays of hadrons produce neutrinos that strike both MINOS and MiniBooNE.
     Parent hadrons ‘sculpted’ by the two detectors’ acceptances.
     Plotted are pT and p|| of hadrons which contribute neutrinos to MINOS (contours) or MiniBooNE (color scale).

-      Parent hadrons ‘sculpted’ by the two detectors’ acceptances.
-      Plotted are pT and p|| of hadrons which contribute neutrinos to MINOS (contours) or MiniBooNE (color scale).

- MINOS

- MiniBooNE

- MINOS

- MiniBooNE

**Two Views of the Hadron Decays**

##      Higher energy neutrinos mostly from particles created in target.

	Interactions in shielding and beam absorber contributes in lowest energy  bins.

     Plots show where the parent was created.

-      Higher energy neutrinos mostly from particles created in target.
- 	Interactions in shielding and beam absorber contributes in lowest energy  bins.
-      Plots show where the parent was created.

***e*

****

*MiniBooNE*

*diagram not to scale!*

**Neutrino Origin Along NuMI Beam Line **

## Neutrino sources along NuMI beamline

- 	Higher energy neutrinos mostly from particles created in target.
- 	Interactions in shielding and beam absorber contributes in lowest energy bins.

**Neutrino sources along NuMI beamline**

## Are the neutrinos coming from the target?

## Flux Uncertainties 

- Focusing uncertainties are negligible.
- Uncertainty is dominated by production of hadrons.
- off the target (estimated from MINOS tuning).
- in the shielding (estimated in gfluka/gcalor).
- in beam absorber (estimated in gfluka, 50% error assigned).

*stopped mesons excluded in this plot*

- MINOS
- Tuning

**Flux Uncertainties **

## MiniBooNE

**(****Boo****ster**** N****eutrino**** E****xperiment)**

**becomes**

**An off axis neutrino experiment**
**using Main Injector**

## NuMI Beam and MiniBooNE Detector

- NuMI events (for MINOS) detected in MiniBooNE detector!

**MiniBooNE Detector:**
**12m diameter sphere**
**950000 liters of oil****(CH****2****)**
**1280 inner PMTs**
**240 veto PMTs**

**Decay Pipe**

*p* beam

- , *K*

**MiniBooNE**

- 

- Main trigger is an accelerator signal indicating a beam spill.
- Information is read out in 19.2 s interval covering arrival of beam.

## Detector Operation and Event reconstruction

- No high level analysis needed to see neutrino events

- Backgrounds: cosmic muons and decay electrons

- ->Simple cuts reduce non-beam backgrounds to ~10-5

- Events in DAQ window:no cuts

- Removed cosmic ray muons:
- PMT veto hits < 6

- Removed cosmic ray muons
- and -decay electrons:
- PMT veto hits < 6 and
- PMT tank hits > 200

- 6-batch structure of MI
- about 10 s duration
- reproduced.

## Detector Operation and Event reconstruction

- The data set analyzed here: 1.42 x 1020 P.O.T.
- We have a factor two more data to analyze!

- The rate of neutrino candidates was constant: 0.51 x 10-15 /P.O.T.
- Neutrino candidates counted with:PMT veto hits < 6 and PMT tank hits > 200

## Particle Identification

******0**** ****→**** ******

** ****electron**** ****candidate**

** ******
**candidate**

** ********0**
**candidate**

- Čerenkov rings provide primary means of identifying
-       products of  interactions in the detector

********** ****n ******** ********-**** p**

******e**** ****n ******** e****-**** ****p**

********** ****p ******** ************ p**** ********0**

**n          n**

**Particle Identification**

## CC +   26% 

**Events from NuMI detected at MiniBooNE**

- CCQE   39%
- CC +   26%
- NC 0     9%

**Neutrino interactions at carbon simulated by **
**NUANCE event generator: neutrino flux **
**converted into event rates.**

**Event**
**rates**

**Event**
**rates**

**Flux**

**NuMI event composition at MB **
********-81%, ******e**-5%,********-13%,******e**-1%

## Analysis Algorithm

## Event Reconstruction 

- -Separate hits in beam window by time into sub-events of related hits.
- -Reconstruction package
-  maximizes likelihood of
- observed charge and time
- distribution of PMT hits to
- find track position, direction
- and energy (from the
- charge in the cone) for
- each sub-event.

**Event Reconstruction **

- The tools used in the analysis here are developed and verified
- in MiniBooNE oscillation analysis of events from Booster beam.

**Phys. Rev. Lett. 98, 231801 (2007),**
** ****arXiv:0704.1500 [hep-ex]**

- Details:

- and

** ****arXiv:0706.0926 [hep-ex]**
**Accepted for publ. by Phys.Rev.Lett.**

- Event selection very similar to what was used in MiniBooNE analyses.

## Analysis Method 

**Analysis Method **

**Apply likelihood fits to three hypotheses:**
**-single electron track**
**-single muon track**
**-two electron-like rings (********0 ****event hypothesis**** )**

**Compare observed light distribution to fit prediction:**
**Does the track actually look like an electron?**

- log(Le/L)<0** ********-like events**

- log(Le/L)>0** e-like events**
**Example from MiniBooNE**
**Oscillation Analysis.**

**log(L****e****/L********)**

**Form likelihood differences using minimized –logL quantities:      **log(Le/L) and log(Le/L)

****

**e**

##   CCQE Analysis

## Analysis of the  CCQE events from NuMI beam 

-  CCQE (+n  +p) has a two “subevent” structure
- (with the second subevent from stopped  e e)

- Event Selection:

- Subevent 1:
-    Thits>200, Vhits<6
-    R<500 cm
-    Le/L**** < 0.02

- Subevent 2:
- Thits<200, Veto<6

**p**

****

**n**

- Scintillation

- Cerenkov **1**

- 12C

- Cerenkov **2**

**e**

- 

- Tank Hits

## Visible E of : final state interactions in  CCQE sample 

- of which 70% are CCQE’s.

- Log(Le/L****)< 0.02

**Visible E of ********: final state interactions in ************ CCQE sample**** **

**Data (stat errors only)**
**compared to MC prediction**
**for visible energy in the **
**tank.**

- Visible energy in tank [GeV]

- CCQE

- CC+

- Monte
- Carlo

- Data

- PRELIMINARY

- CCQE

- CC+

- “other”

- Total MC
***N****X***0
- Beam ***e*
*****p* **
*****n* ***p*
*****n* ***n***+
- Other **** Events
-        Events
-        Events

## Compare  CCQE MC to Data:Parent Components 

- 

- K

**Compare ************ CCQE MC to Data:Parent Components**** **

**MC is normalized to data POT number with no further corrections!**

- Visible energy in tank [GeV]

**Beam MC tuned**
**with MINOS near**
**detector data.**
**Cross-section**
**Monte Carlo**
**tuned with MB**
**measurement of**
**CCQE pars **MA
**and ********.**

- PRELIMINARY

**arXiv:0706.0926 [hep-ex]**

## Compare  CCQE MC to Data:Parent Components 

- 

- K

**Compare ************ CCQE MC to Data:Parent Components**** **

**Predicted Kaons are matching the data out of box!**

- Visible energy in tank [GeV]

- PRELIMINARY

## Systematic Uncertainties in  CCQE analysis 

**To evaluate Monte Carlo agreement with the data need estimate**
**of systematics from three sources:**

**-Beam modeling: ****flux uncertainties****.**
**-Cross-section model: ****neutrino cross-section uncertainties****. **
**-Detector Model:describes how the light emits, propagates, and    **
** ****absorbs in the detector (****how detected particle looks like****?).**

**Detector Model**

**Cross-section**

**Beam**

**Total**

** ****Visible energy [GeV]**

** ****Visible energy [GeV]**

** ****Visible energy [GeV]**

** ****Visible energy [GeV]**

- PRELIMINARY

- PRELIMINARY

## Add Systematic uncertainty to  CCQE Monte Carlo 

**Add Systematic uncertainty to ************ CCQE Monte Carlo**** **

-  visible energy distribution

- Visible energy in tank [GeV]

- Outgoing angular distribution

-       cos 

- Information about
- incoming :wrt NuMI
- target direction.

- 

- K

- 

- K

**Predicted Pions are **
**matching the data **
**within systematics!**

- PRELIMINARY

- PRELIMINARY

##  CCQE sample: Reconstructed energy E of incoming   

**Understanding of the beam demonstrated:**
**MC is normalized to data POT number ****!**

**Reconstructed ****E******** ****QE****:from**** ****E****lepton**** **
**(“visible energy”) and lepton angle **
**wrt neutrino direction**

********** ****CCQE sample: Reconstructed energy ****E******** of incoming ******** **** **

- 

- K

- PRELIMINARY

## Conclusion from  CCQE analysis section 

**There is very good agreement between data and Monte Carlo:the MC need not be tuned.**

**Conclusion from ************ CCQE analysis section**** **

- Because of the good data/MC agreement
- in  flux and because the and e
- share same parents  the beam MC can
- now be used to predict:
- e rate, and
- mis-id backgrounds for a e analysis.

##  e CCQE Analysis

## -0 (0) and radiative  (N) events, and

**we find  background contribution to it:**
- -0** (**0******) and radiative ******** (********N********) events, and**
**-”dirt” events. **

**Backgrounds to **e** CCQE sample**** **

- e CCQE (+n  e+p)

**Therefore, before analyzing ********e**** CCQE we constrain the**
**backgrounds by measurement in our own data.**

## Among the e-like mis-ids, 0 decays which are boosted,  producing 1 weak ring  and 1 strong ring is largest source.

****0 mis-id rate, **measure it!**
- Measured rates of reconstructed 0...
- tie down the  rate of mis-ids

-  decays to a single photon:
- with 0.56% probability:

**Analysis of **0** events from NuMI beam **

- What is applied to select 0s
**Event pre-selection:**
**1 subevent**
**Thits>200, Vhits<600**
**R<500 cm**

- log(**L****e****/L******)>0.05 (e-like) log(**L****e****/L******)<0 (******0**-like)

- 

****

****

- Among the e-like mis-ids, ****0 decays which are boosted,  producing 1 weak ring  and 1 strong ring is largest source.

- p

- +

- 0

- p

- 

- 

- 

- 

## Analysis of 0 events from NuMI beam: 0 mass 

**This sample contains 4900 events of which 81% are ******0** events: ****world second largest ******0  **sample!**

**The peak is 135 MeV/c**2

- e** appear to be well modelled.**

- Monte
- Carlo

- Data

- 0

- e

- 

## Analysis of 0 events from NuMI beam: 0 mass 

**The peak is 135 MeV/c**2

- Monte
- Carlo

- Data

- 0

- e

- 

- The 0 events are well modeled with
- no corrections to the Monte Carlo!

## Analysis of 0 events from NuMI beam: 0 momentum 

- We declare good MC/Data agreement
- for 0 sample going down to low mass
- region where e candidates are showing up!

- Monte
- Carlo

- Data

- 0

- e

- 

- Further
- Cross
- Check!

- PRELIMINARY

## Analysis of dirt events from NuMI beam 

- - “Dirt” background is due to  interactions
-   outside detector. Final states
-   (mostly neutral current interactions)
-   enter the detector.
- - **Measured** in “dirt-enhanced” samples:
- 	- we tune MC to the data selecting a sample
-             dominated by these events.
- -”Dirt” events coming from outside deposit only a fraction
-   of original energy closer to the inner tank walls.
- -Shape of visible energy and event vertex distance-to-wall  distributions   are well-described by MC: good quantities to measure this background
-  component.

## Selecting the dirt events 

- Event pre-selection:
- 1 subevent
- Thits>200, Vhits<600
- R<500 cm

- log(Le/L)>0.05 (e-like)
- Ee <550 MeV
- Distance-to-wall <250 cm
- m<70 MeV/c2 (not 0-like)

**Dist-to-wall of tank along track [m]**

**Visible energy [GeV]**

**Events/bin**

**Events/bin**

- Dirt sample

-  interactions
- in the tank

**Uncertainty in the dirt rate is less than 20%.**

**Fits to dirt enhanced sample:**

- We declare good MC/Data agreement for the dirt sample.

- PRELIMINARY

## Analysis of the e CCQE events from NuMI beam

**Analysis of the ********e**** CCQE events from NuMI beam**

- e CCQE (+n  e+p)

- 1 Subevent
- Thits>200, Vhits<6
- R<500 cm, **E****e**>200MeV

- Likelihood cuts as the
- as shown below

- +

- Likelihood e/ cut

- Likelihood e/ cut

- Mass(0) cut

- Cut region

- Cut region

- Cut region

- Signal region

- Signal region

- Signal region

**Visible energy [MeV]**

**Visible energy [MeV]**

**Visible energy [MeV]**

- MC example plots here come from Booster beam MC

**E****e**>200MeV cut is appropriate to remove e contribution from the dump
- that is hard to model.

## Before we further characterize data/MC agreement we have to account for the systematic uncertainties.

**Before we further characterize data/MC agreement we have to account for the systematic uncertainties****.**

**Data = 783 events.**
**Monte Carlo prediction = 662 events.**

- Visible energy in tank [GeV]

- Monte Carlo

- Data

- 0

- e

- Other 

- dirt

- 

- PRELIMINARY

## Systematic Uncertainties in e CCQE analysis 

**Detector Model**

**Cross-section**

**Beam**

**Total**

** ****Visible energy [GeV]**

** ****Visible energy [GeV]**

** ****Visible energy [GeV]**

** ****Visible energy [GeV]**

- PRELIMINARY

- PRELIMINARY

**“****dirt” component of Xsec: 20% error; ********0**** component of Xsec: 25% error **

## e CCQE events: e visible energy and angular distribution

******e**** CCQE events: e visible energy and angular distribution**

- e visible energy distribution

- Outgoing e angular distribution

- Visible energy in tank [GeV]

-       cos e

- All 

- All 

- 

- K

- 

- KL

- PRELIMINARY

- PRELIMINARY

## e CCQE sample: Reconstructed energy E of incoming   

- e CCQE sample: **Reconstructed energy ****E******** of incoming ******** **** **

- All 

- All e

- PRELIMINARY

## Summary of estimated backgrounds vs data e CCQE sample 

**total background         401****±****66            261****±****50        **
**   ********e ****intrinsic               311                  231      **
**   ******_****__** **__**induced                 90                   30                                    **_
**      ****NC ********0                       ****   30                   25          **
**      ****NC ********→N********               14                    1             **
**      ****Dirt                     35                    1                   **
_**      **__**other                    11                    3               **_
_**Data                      498**__**±**__**22            285**__**±**__**17         **_
_**Data-MC                   97**__****__**70             24**__****__**53**_
_**Significance                1.40 **__****__**            0.45 **__****__**             **_

- Summary of estimated backgrounds vs data e CCQE sample

- At this point systematic errors are large: we cannot saymuch about the difference between low and high-E regions.In the future we will reduce ******e** CCQE sample systematics constraining it with our large statistics ******** CCQE sample.

- Looking quantitative into low energy and high energy region:

## Summary and Future Steps

## We performed analyses of neutrinos from NuMI beam observed with MiniBooNE detector. The sample analyzed here corresponds to 1.42x 1020 protons on NuMI target.

- We observed good description of the data by Monte Carlo
- with both ******** CCQE and e CCQE sample: successful
- demonstration of an off-axis beam at 110 mrad.
******** CCQE sample demonstrated proper understanding of the
- Pion and Kaon contribution to neutrino beam.

- PRELIMINARY

## In the future we will reduce e CCQE sample systematics constraining it with our large statistics  CCQE sample.

- The e CCQE sample will be compared to what we observed with Booster beam.
- We are currently reprocessing and collecting more data
- (expect about 3 x 1020 P.O.T. collected by now.)

- These errors
- will be reduced

- PRELIMINARY