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MiniBooNE Low Energy Analysis. H. Ray Los Alamos National Laboratory. Oscillation Fit Reporting. The final fit for     e oscillations was performed using 2 different analyses Track Based : E  QE 475 MeV to 3 GeV Boosting : E  QE 300 MeV to 3 GeV

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Miniboone low energy analysis

MiniBooNE Low Energy Analysis

H. Ray

Los Alamos National Laboratory


Oscillation fit reporting
Oscillation Fit Reporting

  • The final fit for  e oscillations was performed using 2 different analyses

    • Track Based : EQE475 MeV to 3 GeV

    • Boosting : EQE 300 MeV to 3 GeV

  • Increased from 300 MeV due to 2 fit of 1% in Evis variable during 1st step of unblinding process

H. Ray


Oscillation fit reporting1
Oscillation Fit Reporting

  • We felt that we had checked everything to our full ability, and to our best knowledge could not further constrain processes in the low E region

  • MC studies of potential LSND oscillation signals indicated we could tighten the E requirement with a negligible loss in sensitivity

  • Prior to unblinding, we agreed to also examine events with EQE > 300 MeV in the Track Based analysis

H. Ray



Observed event distribution1
Observed Event Distribution

Background-subtracted

475 MeV to 3 GeV

Counting Expt :

300 MeV < EQE< 1.250 GeV

749 observed evts

631 ± 25 ± 45 expected events

Excess over background : 2.3

H. Ray


Observed event distribution2

Counting Expt :

300 MeV < EQE< 475 MeV

Excess over background : 3.7

Observed Event Distribution

Background-subtracted

475 MeV to 3 GeV

H. Ray


Observed event distribution3

Excluded by Bugey!

Observed Event Distribution

Background-subtracted

300 MeV to 3 GeV

Best Fit (sin22, m2) = (1.0, 0.03 eV2)

2 Probability: 18%, Null Hypothesis= 3%

Only 4% Compatible w/LSND

H. Ray


What are the low e events
What are the Low-E Events?

  • These low Energy events could be many things

  • We saw these events for the first time on Monday, March 26th (2007)

  • The following presents our very preliminary investigations to date

H. Ray


Fit energy event composition
Fit Energy Event Composition

intrinsic e

 mis-id

  • Boost Analysis

  • 300 MeV to 3 GeV

  • Likelihood Analysis

  • 475 MeV to 3 GeV

H. Ray


Low energy event composition
Low Energy Event Composition

intrinsic e

 mis-id

  • Boost Analysis

  • 300 MeV to 475 MeV

  • Likelihood Analysis

  • 300 MeV to 475 MeV

H. Ray


Fundamental information
Fundamental Information

Low E events show no bias in

event time

Not normalized to POT

369 events

369 events

Shutdowns

H. Ray


Cosmic rays
Cosmic Rays

Measured from our strobe data

Low E events show no bias in

Y (vertical) position

Cosmic events populate

upper region of tank

369 events

H. Ray

2 expected evts in osc. analysis


Radiative delta and nc 0
Radiative Delta and NC0

  • Constrain our NC0 production rate using data from our detector

    • Reduces error on mis-id 0 (<2%!)

  • This also constrains the radiative  resonance rate, thus constraining rate of  N 

H. Ray


What we know so far
What we know so far

  • Low E events pass EM Particle ID

    • Gamma or electron

  • The evts do not appear to be biased in run range or event time

  • The evts do not appear to be due to cosmic ray background

  • Radiative Delta : unlikely = need x3 increase

  • NC0 : unlikely = measure very well with our data

H. Ray


Summary
Summary

  • A two-neutrino appearance only model systematically disagrees with the shape of the excess as a function of E

  • Need to investigate non-oscillation explanations of the low E excess

  • Investigation of these low E events is underway

H. Ray


Final results
Final Results

  • Any conclusions drawn about the low E events will have no effect on our oscillation result

H. Ray


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