# Presentation: 947825

##                     Updated Oscillation Results from MiniBooNE                     

**                    ****Updated Oscillation Results from MiniBooNE                     **

- R.G. Van de Water
- Los Alamos National Laboratory
- P-25

## Outline

- The LSND oscillation signal.
- The MiniBooNE experiment: Testing LSND.
- Tuning the Monte Carlo
- Original oscillation results.
- New results on low energy anomaly.

## For oscillations to occur, neutrinos must have mass!

## Neutrino Oscillations Have Been Observed!

**SuperK, SNO, KamLAND**
**(Very long baseline)**

**SuperK, K2K, MINOS**
**(intermediate baseline)**

**LSND?**
**(short baseline)**

## Evidence for Oscillations from LSND

- Extremely small mixing amplitude!

## Current State of Neutrino Oscillation Evidence

- Expt.	Type		m2 (eV2)	 sin22
- LSND	e		     ~1  ~3x10-3
- Atm.  x		~2x10-3	~1
- Solar	ex	        ~8x10-5	~0.8

**3-******** oscillations require**
******m****12****2**** + ********m****23****2**** = ********m****13****2 **
**and cannot explain the data!**

## If LSND Excess Confirmed: Physics Beyond the Standard Model!

**3+2 Sterile Neutrinos ****	****	**Sorel, Conrad, & Shaevitz  (PRD70(2004)073004)
- 			**	**				**Explain Pulsar Kicks?**
**	****	****	****	****	****	****	****	****Explain R-Process in Supernovae?**
**	****	****	****	****	****	****	****	****Explain Dark Matter?**
**	**
**Sterile Neutrino**			Kaplan, Nelson, & Weiner  (PRL93(2004)091801)
**	****	****	****	****	****	**		**Explain Dark Energy?**
**New Scalar Bosons****	**      Nelson, Walsh  (arXiv:0711-1363)
**CPT Violation         **** ****	****	**Barger, Marfatia, & Whisnant  (PLB576(2003)303)
**                    ****	****	****	****	****Explain Baryon Asymmetry in the Universe?**
**Quantum Decoherence****	**Barenboim & Mavromatos  (PRD70(2004)093015)
**Lorentz Violation****	****	****	**Kostelecky & Mewes  (PRD70(2004)076002)
- 							Katori, Kostelecky, Tayloe (hep-ph/0606154)
**Extra Dimensions****	**		Pas, Pakvasa, & Weiler (PRD72(2005)095017)
**Sterile Neutrino Decay****	****	**Palomares-Ruiz, Pascoli, & Schwetz (JHEP509(2005)48)

## Review of the MiniBooNE Experiment

## MiniBooNE: A Test of the LSND Evidence

**for Oscillations: ****Search for ******* ******e***

**Alabama, Bucknell, Cincinnati, Colorado, Columbia, Embry-Riddle,****	**
**Fermilab, Florida, Indiana, Los Alamos, LSU, Michigan, Princeton, **
**                             ****St. Mary's, Virginia Tech, Yale**

- Completely different
- systematic errors
- than LSND
- Much higher energy
- than LSND
- Blind Analysis

## Slide 10

## Booster

**Booster**

- Target
- Hall

- 4 1012 protons per 1.6 s pulse
- delivered at up to 5 Hz.
- 6.3 1020 POT delivered 2002
- thru end of 2005

***MiniBooNE extracts beam ***
***from the 8 GeV Booster***

- Delivered to a  1.7  Be target

- within a magnetic horn
- (2.5 kV, 174 kA) that
- (increases the flux by 6)

- Collected another 1 x 1020 POT
- during 2007 SciBooNE Run

## The MiniBooNE Detector (arXiv: 0806.4201)

-  541 meters downstream of target
-  3 meter overburden
- 12.2 meter diameter sphere
-         (10 meter “fiducial” volume)
-  Filled with 800 t
- 	of pure mineral oil (CH2)
- 	(Fiducial volume: 450 t)
- 1280 inner phototubes
-     (10% photocathode coverage),
- 	240 veto phototubes
- Simulated with a GEANT3 Monte Carlo

***The MiniBooNE Detector (arXiv: 0806.4201)***

## MiniBooNE Detector Tank, Lots of Valuable Oil!

## Picture of LSND photomultipliers (used later in MB)

- hep-ex/0404034

- Electronics reused as well.

## A 19.2 s beam trigger window encompasses the 1.6 s spill

- Raw data

- Veto<6  removes
- Cosmic ray muons
- leaving
- “ Michel electrons”
- (ee)

- Tank Hits > 200
- (equivalent to energy)
- removes Michel electrons,
- which have
- 52 MeV endpoint

- Tank time for first subevent

## Stability of running:

- Observed and
- expected events
- per minute

- Full  Run

## Oscillation Analysis

## MiniBooNE oscillation analysis structure

- Start with a Geant 4 flux prediction for the  spectrum from  and K produced at the target
- Predict  interactions using the Nuance cross section parameterization
- Pass final state particles to Geant 3 to model particle and light propagation in the tank
- Starting with event reconstruction, independent analyses:   -  Boosted Decision Tree (BDT)    -  Track Based Likelihood (TBL)
- Develop particle ID/cuts to separate signal from background
- Fit reconstructed E spectrum for oscillations, apply muon constraint and systematic errors (full error matrix with correlations).

**Boosting****Particle ID**

**Likelihood****Particle ID**

- BaselineAnalysis

##   e e

-   e e
-                 K  e e

-  K 

-  

- Antineutrino content: 6%

***Neutrino Flux from GEANT4 Simulation***

- “Intrinsic” e + e sources:
-   e+ e    (52%)
- K+  e+ e   (29%)
- K0  e e       (14%)
- Other	       (  5%)

-  e/ = 0.5%

- See Flux paper for details
- arXiv: 0806.1449

**Notes:**
epanding “other”...mu- -> e- numu nuebar: 2%   pi+ -> e+ nue: 2% other: 1%

## Meson production at the target

- HARP collaboration,
- hep-ex/0702024

- Kaons:

- Pions:

- MiniBooNE members joined the HARP collaboration
- 8 GeV proton beam
- 5% Beryllium target
- Data were fit to Sanford-Wang parameterization

- Kaon data taken on multiple targets in 10-24 GeV range
- Fit to world data using Feynman scaling
- 30% overall uncertainty assessed

## Predicted event rates before cuts

***Predicted event rates before cuts***
***(NUANCE Monte Carlo)***

- D. Casper, NPS, 112 (2002) 161

- Event neutrino energy (GeV)

## CCQE Scattering (Phys. Rev. Lett 100, 032301 (2008))

- Fermi Gas Model describes CCQE
-  data well
- MA = 1.23+-0.20 GeV
- κ = 1.019+-0.011
- Also used to model νe interactions

**Kinetic Energy of muon**

- From Q2 fits to MB  CCQE data:
-      MAeff -- effective axial mass
-      κ    --  Pauli Blocking parameter
- From electron scattering data:
-      Eb -- binding energy
-      pf  -- Fermi momentum

- data/MC~1
- across all
- angle vs.energy
- after fit

***CCQE Scattering ******(Phys. Rev. Lett 100, 032301 (2008))***

- Data/MC Ratio

## Tuning the MC on internal NCπ0data

- NC π0 important background
- 90%+ pure π0 sample (mainly Δ→Nπγ)
- Measure rate as functionof momentum
- Default MC underpredicts rate at low momentum
- Δ→Nγ also constrained

- Tuning the MC on internal NCπ0data

- Invariant massdistributions in
- momentum bins

## MiniBooNE is a Cerenkov Light Detector:

- Muons (or charged pions):
- Produced in most CC events.
- Usually 2 or more subevents
-  or exiting through veto.
- Electrons:
- Tag for e CCQE signal.
- 1 subevent
- 0s:
- Can form a background if one
- photon is weak or exits tank.
- In NC case, 1 subevent.

## Slide 25

## Slide 26

##  Log(Le/L)

-  Log(Le/L)
-  + Log(Le/L)
-  + invariant mass

- νe Backgrounds after cuts

***Summary of Track Based ******ν******e****** cuts***

- “Precuts”   +

- LSND oscillations adds
- 100 to 150 νe events

**E****ν****QE**

**Notes:**
cut to rject low energy events near wall is:   .not.(R>426 cm .and. Evisible<280)

## First νμ → νe  Oscillation Result from One year ago.

## The Track-based e  Appearance-only  Result:

***The Track-based ************************e******  Appearance-only  Result:***

## The result of 

***the ************************ ************e****** appearance-only analysis***
***is a ***_***limit***_*** on oscillations:***

- Energy fit:  475<EQE<3000 MeV

- Simple 2-neutrino
- oscillations excluded
- at 98% C.L.

- Phys. Rev. Lett. 98, 231801 (2007)

## Ten Top Physics Stories for 2007

**Ten Top Physics Stories for 2007**

**The MiniBooNE experiment **
**at Fermilab solves a neutrino**
**mystery.**

## But an Excess of Events Observed Below 475 MeV

- 96 ± 17 ± 20 events
- above background,
- for 300< E QE <475MeV

- Deviation:
-  3.7 

- Excess Distribution inconsistent with a 2-neutrino oscillation model

## Going Beyond the First Result

- Investigations of the Low Energy Excess
- Possible detector anomalies or reconstruction problems
- Incorrect estimation of the background
- New sources of background
- New physics including exotic oscillation scenarios, neutrino decay, Lorentz violation, .......

***Any of these backgrounds or signals could have an important impact******on other future oscillation experiments.***

## Re-analysis of the Low Energy Anomaly

## Improvements in the Analysis 

-  Rechecked various background cross-section and rates
-   (******0**, N, etc.)
-  Improved 0 (coherent) production incorporated.
-   Better handling of the radiative decay of the Δ resonance
-   Photo-nuclear interactions included
-  Developed cut to efficiently reject “dirt” events.
-  Analysis threshold lowered to 200 MeV, with reliable errors.
-  Systematic errors rechecked, and some improvements made
-   (i.e. flux, N, etc).
-  Additional data set included in new results:
-           Old analysis:    5.58x1020 protons on target.
-           New analysis:   6.46x1020 protons on target.

**Improvements in the Analysis **

## Detector Anomalies or Reconstruction Problems

- No Detector anomalies found
- - Example: rate of electron candidate events is
-   constant (within errors) over course of run

- No Reconstruction problems found
- - All low-E electron candidate events have   been examined via event displays,   consistent with 1-ring events

***Signal candidate events are consistent with single-ring neutrino interactions******        ************  But could be either electrons or photons***

## Measuring 0 and constraining misIDs from 0

**Phys.Lett.B664, 41(2008)**

**Measuring ********0**** and constraining misIDs from ********0**

- 0 rate measured to a few percent.
- Critical input to oscillation analysis:
- without constraint 0 errors would
- be ~ 20%

*The **π**0 ‘**s constrains the **Δ** **resonance rate, *
*which determines the rate of **Δ****N**γ**.*

**Pion analysis rechecked, only small changes made**

** ********0 **** reweighting applied**
**to the monte carlo**

## Improved π0 and radiative Δ analysis

- Applied *in situ* measurement of the  coherent/resonant production rate
- Coherent event kinematics more forward
- Resonant production increased by 5%
- Improvements to Δ -> Nγ bkg prediction
-  Resonant π0 fraction measured more accurately
- Old analysis, π created in struck nucleus not allowed to reinteract to make new Δ
- Δ -> Nγ  rate increased by 2%
- Error on Δ -> Nγ increased from 9 to 12%
- bottom line:  Overall, produces a small change in νe appearance bkgs

- Z

- 

- p,n

- p,n

- 

- 

- 

- C

- Z

- C

- 

- 

- 

## Photonuclear absorption of 0 photon

***  *****Since MiniBooNE cannot tell an electron from a single gamma, any process that leads to a single gamma in the final state will be a background**
- Photonuclear processes can remove (“absorb”) one of the gammas from NC 0   event
- Total photonuclear absorption cross sections
-    on Carbon well measured.

- +N+N

**Giant****Dipole****Resonance**

**P****hotonuclear absorption of ********0 ****photon**

- Photonuclear absorption was missing from
- our GEANT3 detector Monte Carlo.
-  Extra final state particles carefully modelled
-  Reduces size of excess
-  Systematic errors are small.
-  No effect above 475 MeV

- π0

**Photon absorbed**
**By C****12**

**Remaining photon **
**Mis-ID as an electron**

## Estimated Effects of Photonuclear Absorption

***   ***

**Photonuke adds ~25% to pion background in the 200 <E < 475 MeV region**

**E****ν****QE**

**No. Events**

## Reducing Dirt Backgrounds withan Energy Dependent Geometrical Cut

- Dirt events tend to be at large radius, heading inward
- Add a new cut on distance to wall in the track backwards direction, optimized in bins of visible energy.
- Has significant effect below 475 MeV
-  Big reduction in dirt
-  Some reduction of 0
-  Small effect on e
- Has almost no effect above 475 MeV

- In low energy region there is a
- significant background from neutrino
- interactions in the dirt

- MC:

## Effects of the Dirt Cut

- Effects of the Dirt Cut

-  The dirt cut:
- significantly reduce dirt background by ~80%,
- reduce pion background by ~40%
- reduce electron/gamma-rays by  ~20%.

**E********QE**

**No Dirt Cut**

**With Dirt Cut**

**No. Events**

**E********QE**

## Sources of Systematic Errors

-  Flux from K+ decay			1.4 		       5.7	    	             √
-  Flux from K0 decay 			0.5 		       1.5  		             √
-  Target and beam models		1.3 		       2.5
-   -cross section 		               5.9 	             11.8	       	     √
-  NC 0 yield					1.4  		       1.8		             **√**
-  External interactions (“Dirt”) 	0.8  	     	       0.4	   	           **√**
-  Optical model				9.8  	      	       5.7   	   	     √
-  DAQ electronics model		5.0 	      	       1.7 **
-  Hadronic                                    0.8                   0.3 (new error)
-  Total Unconstrained Error          13.0                 15.1

- Source of
- Uncertainty
- On e background

- Checked or
- Constrained
- by MB data

- Track Based
- error in %

**200-475 MeV**

**475-1250 MeV**

- All Errors carefully rechecked; ** = significant decrease

## New Results 

**total background         186.8****±****26       228.3****±****24.5    385.9****±****35.7**
**   ********e ****intrinsic              18.8               61.7             248.9**
**   ******_****__** **__**induced              168                166.6            137         **_
**      ****NC ********0                       ****103.5              77.8             71.2**
**      ****NC ********→N********            19.5                47.5             19.4**
**      ****Dirt                  11.5              12.3             11.5      **
_**      **__**other                33.5                29              34.9   **_
_**Data                      232                  312             408  **_
_**Data-MC                 45.2**__****__**26          83.7**__****__**24.5      22.1**__****__**35.7**__** **_
_**Significance               1.7**__****__**               3.4**__****__**             0.6**__****__** **_

**The excess at low energy remains significant!**

**New Results **

**MC systematics**
**includes data**
**statistics.**

- This will be
- Published soon.

**“****other” mostly**
**muon**** mid-ID’s**

## Excess Significance For Different Analysis

**Original analysis**
**5.58E20 POT**

**Revised analysis**
**5.58E20 POT**

**Revised Analysis**
**6.46E20 POT**

**Revised Analysis**
**6.46E20 POT**
**With DIRT cuts**

## Oscillation Fit Check 

**Inclusion of low energy excess does not improve oscillation fits**

- No changes in fits above 475 MeV

**Oscillation Fit Check **

-                           E>475 MeV  E>200 MeV
- Null fit 2 (prob.):   9.1(91%)     22(28%)
- Best fit 2 (prob.):  7.2(93%)   18.3(37%)

**475 MeV**

**E****v**** > 475 MeV**

## Properties of the ExcessIs it Signal like?

## Dirt Cuts Improves Signal/Background

**Dirt Cuts Improves Signal/Background**

- No DIRT cuts

- With DIRT Cuts

- Excess decreases by ~7%, consistent with electron/gamma-ray signal

- S/B ~1/5

- S/B ~ 1/3

## Reconstructed Radius

- Excess is uniformly distributed throughout tank.
- 	-consistent with neutrino induced interactions

**Radius (cm)**

**Radius (cm)**

**Ratio Data/MC**

**Statistical Errors**

## Reconstructed Visible Energy (Evis)

**Reconstructed Visible Energy (E****vis****)**

- Pronounced excess/peak
- From 140 - 400 MeV

- Excellent agreement
- for Evis > 400 MeV

- Excess does not track νμ backgrounds or νe intrinsics!

**Includes systematic errors**

## Low Energy Excess Remains Significant!

- It is consistent with low energy production of neutrino induced electrons or gamma-rays.
- Actively performing fits to event kinematics (visible energy, beam angle, Q**2) to help identify source, e.g. gamma-ray or pion background, mis-identified muons, νe, νe, etc.

## What is the Source of the Excess?- Theoretical ideas- Other data sources

## Is MiniBooNE Low Energy Excess consistent with LSND??

- LSND assumed excess was two neutrino oscillations,
- Prob(**ν****μ**** → ****ν****e****)** = sin2(2θ) sin2(1.27  Δm2  L/E)
- Both LSND and MiniBooNE are at the same L/E and look for an excess of (anti)electron neutrinos in a (anti)muon neutrino beam
- Yes, consistent! Though looking at different charge species.
- LSND measures Prob(**ν****μ**** → ****ν****e**)=  (0.25 +/- 0.08) %,      MiniBooNE measures Prob(**ν****μ**** → ****ν****e**)=  (0.30 +/- 0.10)% at low E.
- Yes, consistent!
- MiniBooNE fails two neutrino oscillation fits to reconstructed neutrino energy.
- No, not consistent!!  Requires more complicated oscillations, e.g. 3+2

## The low E excess has fueled much speculation...

- Commonplace

- SM, but odd

- Beyond the SM

- Muon bremstrahlung                     (Bodek, 0709.4004)

- Anomaly-mediated γ (Harvey, Hill, Hill, 0708.1281)

- New gauge boson            (Nelson, Walsh,0711.1363)

- Easy to study in MB with much larger stats from events with a Michel tag
- Proved negligible in 0710.3897

- Still under study, large rate uncertainties
- NC process; anti-neutrino data will determine if it is source of the excess

- Firm prediction for anti-neutrinos
- Many other beyond the Standard Model ideas.

## Muon Misidentification(including muon internal bremsstrahlung) 

- Muon Misidentification(including muon internal bremsstrahlung)

- Data-MC excess, but note the scale!

- Apply reconstruction and particle
- identification to clean sample muon
- CCQE events (muon decay visible).
- Then scale normalization to account for
- how often the second subevent is missing
- What results is a direct measurement and MC
- prediction for almost all the rate at which events
- with a final state muon enter the ne background

- -Misidentified Muons not a problem.

- Paper on this work:
- arXiv:0710.3897  [hep-ex]

## Axial Anomaly- an explanation within the standard model

## Other Data Sources

- Limitations of MiniBooNE:
- We do not have two detectors or complete set of source and background calibration sources.
- We do have different detectors and sources of neutrinos that provide more information on background estimates, signal cross sections, PID, etc
- SciBooNE detector at 100m -- measure neutrino flux and cross sections.
- Off axis neutrinos (NuMI) -- **ν****e** rich source.
- Anti-neutrino running -- similar backgrounds to neutrino mode.

## Events from NuMI detected at MiniBooNE

**Events from NuMI detected at MiniBooNE**

**Event**
**rates**

**Flux**

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

**Decay Pipe**

*p* beam

- , *K*

**MiniBooNE**

- 

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

**Energy similar to MB as off angle**

- MB ~0.5%

## PRELIMINARY

- e CCQE (+n  e+p)

-  CCQE (+n  +p)

**Very different backgrounds **
**compared to MB (Kaons vs Pions)!**** **

**Systematics not yet constrained!**

- 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.

********** ****CCQE and ********e**** CCQE samples from NuMI **** **

- NuMI νe data provide limits on cross sections and PID

## MiniBooNE Anti-neutrino Run

- In November 07 Physics
- Advisory Committee (Fermilab)
- recommended MiniBooNE
- run to get to a total of
- 5x1020 POT in anti neutrino
- mode.
- Provides direct check of LSND
- result.
- Provides additional data set for
- low energy excess study.
- Collected ~3.3x1020 POT so far.
- Oscillation data set “blinded”.
- Box planned to be opened soon!

**MiniBooNE Anti-neutrino Run**

- MiniBooNE is currently taking data in anti-neutrino mode.

- Sensitivity

## Comparing Neutrino/AntineutrinoLow Energy e Candidates

- Comparing Neutrino/AntineutrinoLow Energy e Candidates

**Neutrino**

**AntiNeutrino**

- Background breakdown is very similar between
- neutrino and antineutrino mode running

-  Various background/signal hypotheses for the excess can have measurably           different effects in the two modes:
- Backgrounds at low energy, expect an excess of 15 to 25 events
- Two neutrino oscillations produce ~20 events at higher energy
-  Can compare the two modes to  test some of the hypotheses

- 3.3x1020 POT

**E********QE**

**E********QE**

- 6.5x1020 POT

**Event rate **
**Down by x9**

## Conclusions

** **

- Despite recent progress, many basic properties of neutrinos are still unknown and the possibility of future surprises remains strong!
- MiniBooNE rules out a simple two neutrino **ν****μ**** → ****ν****e** appearance-only model as an explanation of the LSND excess at 98% CL.  (Phys. Rev. Lett. 98, 231801 (2007), arXiv:0704.1500v2 [hep-ex])
- This is still true!
- However, a 128.8+/-43.4 event (3.0σ) excess of electron or gamma-ray events are observed in the lower energy range from 200 < Eν < 475MeV.
- This could be important to next generation long baseline neutrino experiments (T2K, Nova).
-  This unexplained deviation is under intense investigation.
- Event kinematics, Antineutrino data, and NuMI data will provide more information, stay tuned!
- New Experiments might be required to fully understand the low energy excess.

## BACKUP SLIDES

## The weak force...force of transmutation

- Charged Current

- Makes the weak interaction truly a force of transmutation
- The CC channel converts neutrinos into their charged alter egos
- Converts -1/3 charge quarks into +2/3 counterparts
- Incidentally, CC also proves that we have three distinct neutrino flavors

**W-**

**W-**

**W**+

**W+**

## Probability of Neutrino Oscillations

**P******** = ****************i********j********U********i**** ****U*********i ****U*********j**** ****U********j ********sin****2****(1.27********m****ij****2****L/E********)**** **

**As N increases, the formalism gets rapidly more complicated!**

**N****	****	****	****	****#********m****ij****2****	****	****	****	****#********ij****	****	****	****	****#CP Phases**
**2****	****	****	****	****   ****1****	****	****	****	****	**** 1****	****	****	****	****	****   ****0**
**3****	****	****	****	****   ****2****	****	****	****	****	**** 3****	****	****	****	****	****  1**
**6****	****	****	****	****   ****5****	****	****	****	****	****15****	****	****	****	****      ****10**

## Measuring 0 and constraining misIDs from 0

**Phys.Lett.B664, 41(2008)**

**Measuring ********0**** and constraining misIDs from ********0**

- 0 rate measured to a few percent.
- Critical input to oscillation analysis:
- without constraint 0 errors would
- be ~ 20%

*The **π**0 ‘**s constrains the **Δ** **resonance rate, *
*which determines the rate of **Δ****N**γ**.*
*Rechecked **Δ** re-interaction rate.*
*Increased errors 9 -> 12%*

**Pion analysis rechecked, only small changes made**

**Extract  ********0 **** rate **
**in momentum bins**

## Checks and Changes in the low Energy Region

- Instrumental background?  NO
- Track and Boosting analyses consistent?  YES
- Is excess electron/gamma ray like? YES
- Dirt or Delta(1232) radiative decays?  NO
- Pion or muon mis-id (including brem.)?  NO
- Photonuclear process.  Excess down ~30%
- More comprehensive hadronic errors and better handling of pi+/- interactions.  Excess down slightly
- Modification of pi0 background calculation.  Excess down slightly
- Improved measurement of pi0 backgrounds. Excess up slightly
- Better handling of beam pi+ production uncertainties.  Smaller error
**None of these are expected to have any appreciable effect above 475 MeV**

## The MiniBoonE Low energy Excess remains, the question now is whether the Low-Energy Excess is due to a Signal?

- Anomaly Mediated Neutrino-Photon Interactions at Finite 	Baryon Density (arXiv:0708.1281: Jeffrey A. Harvey, Christopher T. Hill, Richard J. Hill)
- New Scalar Boson: Nelson & Walsh, arXiv:0711-1363
- CP-Violation 3+2 Model: Maltoni & Schwetz, arXiv:0705.0107
- Extra Dimensions 3+1 Model: Pas, Pakvasa, & Weiler, Phys. Rev. D72 (2005) 095017
- Lorentz Violation: Katori, Kostelecky, & Tayloe,  Phys. Rev. D74 (2006) 105009
- CPT Violation 3+1 Model: Barger, Marfatia, & Whisnant, Phys. Lett. B576 (2003) 303

## Multiple hits within a ~100 ns window form “subevents”

- Most events are from  CC interactions,
- with characteristic  two “subevent” structure from stopped ee

- Event structure: “subevents”

## Updates to Low Energy e Prediction

- Included photonuclear effect
- Absent from GEANT3 – creates background from 0s
- More comprehensive hadronic errors
- e.g. uncertainties in final state following photonuclear interaction
- Better handling of beam + production uncertainties
- Errors propagated in model-independent way
- Improved measurement of  induced 0s
- e.g. finer momentum binning
- Incorporation of MiniBooNE 0 coherent/resonant measurement
- No longer need to rely on more uncertain past results
- Better handling of the radiative decay of the  resonance
- Comprehensive review of how the 0,+ radiative decay rate is inferred from the measured 0 rate

- Arrows indicate whether effect is to increase or decrease the low energy data excess
- The effects have different magnitudes despite the arrows all being the same size

- Nearing the end of a comprehensive review of the e appearance backgrounds and their uncertainties
- 	→ Not Quite Ready for Release Yet

## Inclusion of SciBooNE as a

- near detector, dramatically improves
- the sensitivity by reducing flux
- and cross section uncertainties

- Many oscillations models predict large muon disappearance.

## Future Work

**Continue to investigate low energy excess**
**Consider other backgrounds and/or signals**
**Analyze antineutrino data, NuMI ******** in MiniBooNE data, & SciBooNE data.**
**Approved to run one more year to collect enough antineutrino data to test LSND with antineutrinos. **
**If low-energy excess is consistent with a signal, new experiments at FNAL (BooNE) and/or SNS (OscSNS) will be proposed to continue exploring interesting physics at this L/E region. **

**Anti-nue Appearance Sensitivity**

- Currently have
- 2.3E20POT

## numu->nue Oscillation Fits 

**Energy  ****χ****2_null(prob) ****χ****2_bf(prob)  (dm2, sin2theta)**
**>200       22.0(28%)      18.3(37%)     (3.1, 0.0017)**
**>300       21.8(24%)      18.3(31%)     (3.1,  0.0017)**
**>475       9.1(91%)        7.2(93%)       (3.5, 0.0012)****  **

- -Low energy best fits only marginally
-  better than null!
- -Above 475, fit consistent with original
-   results, i.e. inconsistent with two
-   neutrino oscillations.

## Each event is characterized by 7 reconstructed variables:

***Each event is characterized by 7 reconstructed variables:***
-          vertex *(x,y,z)*, time, energy, and direction *(****)**(U**x**, U**y**, U**z**)*.
- 	Resolutions: 	vertex: 22 cm
- 		          		direction: 2.8
- 		          		energy: 11%

-  CCQE events

- 2 subevents
- Veto Hits<6
- Tank Hits>200

## Event “pre-cuts”:

- Veto hits < 6

- Tank hits > 200

- Only 1 subevent

- And a  radius precut:
- 	R<500 cm
- 	(where reconstructed R
- 	is algorithm-dependent)

- data
- MC

## NuMI vs Booster Beam at MiniBooNE 

- Recall:1) Distance to MiniBooNE: L (from NuMI source)  1.4 L (from Booster beam source).2) Neutrino Oscillation depends on L and E through L/E ratio.Therefore, if an anomaly seen at some E in Booster beam data is due to oscillation it should appear at 1.4E in the NuMI beam data at MiniBooNE.

- Currently collecting and
- analyzing more data from NuMI beamline!

## Oscillations Fits

- Fit above 475 MeV

- Fit above 200 MeV

## Background Rates (with DIRT cuts)

## Publications: Lots or results coming out, more to come!

- A.A. Aguilar-Arevalo et. Al.:
-      0707.0926, PRL 98, 231801 (2007) Oscillation search
-      0706.0926, PRL 100, 032301 (2008)  numu CCQE
-      0706.3897, showing mu internal bremsstrahlung small
-      0803.3423,  submitted to PL, neutral current pi0 prod.

- In draft form within the collaboration:
- 3 NIM papers--Flux, Detector, and Reconstruction
- 3 others--combined limits, NUMI/MB, improved osc fit

- 9 further physics papers in various stages of progress
- At least 8 more contemplated

## OscSNS at ORNL: A Smoking Gun Measurement 

**of Active-Sterile Neutrino Oscillations**

-  -> e ; e p -> e+ n  => re-measure LSND an order of magnitude better.
-  -> s ; **Monoenergetic ************ **;  C ->  C*(15.11) => search for sterile ν

- OscSNS would be capable of making precision measurements
- of e appearance &  disappearance and proving, for example, the
- existence of sterile neutrinos! (see Phys. Rev. D72, 092001 (2005)).
- Flux shapes are known perfectly and cross sections are known very well.

**SNS: ~1 GeV, ~1.4 MW **

## Sterile Neutrinos in the Standard Model Gauge Group

- With spontaneous symmetry breaking, Dirac neutrino mass terms of type,
- Neutrino mass implies vR exits!
- vR has the quantum numbers of the vacuum, thus sterile with respect to the standard model gauge interactions!
- SM with neutrino mass now looks like,
- Open question as to mass of sterile states.  Look for Active-Sterile neutrino oscillations.

- vR ~ (1,1)(0)

## 3+2 Analysis

**Experimental constraints from:**
**LSND, KARMEN, NOMAD, ****MB****, CCFR, CDHS, CHOOZ, BUGEY (+ atm constraint)**

**appearance experiments**
**(ν****μ**** ******** ν****e****)**

**disappearance experiments**
**(ν****μ**** ******** ν****μ**** or ν****e**** ******** ν****e****)**

**Idea: If light sterile neutrinos (****ν****s****) exist, then:**
**	**
**ν****μ**** ******** ****ν****s**** ******** ****ν****e**
**	**
**	**
**ν****μ**** ******** ****ν****s**
**ν****e**** ******** ****ν****s**

**(ν****μ**** disappearance **
**Constraint)**

- With SBL approximation  Δmsolar=0, ΔmATM=0, and xij= ΔmijL/4E

- Includes CP phase; φ = -φfor antineutrinos

- 3+2 models can produce differences between neutrino and
-                           antineutrino appearance rates!

- M. Sorel, et. al. hep-ph/0305255

## 3+2 Global Fit Results

- 3+2 neutrino models:
-  provide a **good fit** to LSND and the original MB oscillation data
-  can **account for the low energy** event **excess in MB**

- However:
-  there is significant **tension** **between             appearance and disappearance data**

***Analysis by Maltoni & Schwetz******[hep-ph/0705.0107]***

## Slide 84

##       Detected photons from

-  Prompt light (Cherenkov)
-  Late light (scintillation, fluorescence)
- 		in a 3:1 ratio for ~1

- Attenuation length:  >20 m @ 400 nm

*We have developed *
*39-parameter*
*“**Optical Model”*
*based on internal calibration*
*and external measurement*

- Optical Model

## Cuts Used to Separate  events from e events

- Likelihood e/ cut

- Likelihood e/ cut

- Mass(0) cut

- Combine three cuts to accomplish the separation: Le , Le , and 2-track mass

- Blue points are signal e events
- Red points are background CC QE events
- Green points are background  NC 0 events

- Cut region

- Cut region

- Cut region

- Signal region

- Signal region

- Signal region

**Compare observed light distributions to fit prediction:**

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

- TBL Analysis

## Event Reconstruction

- Use energy deposition and timing of hits in the phototubes
- Prompt Cherenkov light
- Highly directional with respect to particle direction
- Used to give particle track direction and length
- Delayed scintillation light
- Amount depends on particle type

## Slide 88

## Global Fits to Experiments

| LSND | KARMEN2 | MB | Bugey | Max Compat % | Δm2 | sin2θ |
| --- | --- | --- | --- | --- | --- | --- |
| X | X | X |  | 25.36 | 0.072 | 0.256 |
| X | X | X | X | 3.94 | 0.242 | 0.023 |
|  |  |  |  |  |  |  |
| X |  | X |  | 16.00 | 0.072 | 0.256 |
| X |  | X | X | 2.14 | 0.253 | 0.023 |
|  |  |  |  |  |  |  |
|  | X | X |  | 73.44 | 0.052 | 0.147 |
|  | X | X | X | 27.37 | 0.221 | 0.012 |

## Antineutirno Oscillation Fits

**Approved to run one more year to collect enough antineutrino data to test LSND with antineutrinos. **
**Have already taken 0.9E20 POT**
**Working to open the antineutrino box soon.**

**Anti-nue Appearance Sensitivity**

- Currently have
- 2.3E20POT

## 10% Photocathode coverage

-   Two types of
-   Hamamatsu Tubes:
-   R1408, R5912
-   Charge Resolution:
-   1.4 PE,  0.5 PE
-   Time Resolution
-   1.7 ns, 1.1ns

## Identifying Neutrinos

## The Liquid Scintillator Neutrino Detector at LANL

- hep-ex/0404034

- —

- —

- LSND looked for e appearing in a  beam
- Signature:
- Cerenkov light from e+ (CC)
- Scintillation light from nuclear recoil
- Delayed n-capture (2.2 MeV)

##  Log(Le/L)

-  Log(Le/L)
-  + Log(Le/L)
-  + invariant mass

- Backgrounds after cuts

***Summary of Track Based cuts***

- “Precuts”   +

**Notes:**
cut to rject low energy events near wall is:   .not.(R>426 cm .and. Evisible<280)