a search for sterile neutrinos in minos
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A Search for Sterile Neutrinos in MINOS. Thomas Osiecki University of Texas at Austin For the MINOS Collaboration. Motivation for Sterile Neutrinos Sterile Neutrino Signature in MINOS Experimental Challenges Sensitivity Outlook. Motivation For Sterile Neutrinos. - PowerPoint PPT PresentationTRANSCRIPT
APS April 22, 2006 Session C12 1
A Search for Sterile Neutrinos in MINOS
Thomas OsieckiUniversity of Texas at AustinFor the MINOS Collaboration
• Motivation for Sterile Neutrinos • Sterile Neutrino Signature in MINOS• Experimental Challenges• Sensitivity• Outlook
APS April 22, 2006 Session C12 2
m2sol + m2
atm m2LSND
Implies the existence of more than 3 neutrinos!
LEP has measured three active neutrinos that couple to the Z boson.
If there were more than 3 neutrinos, they would not couple to the Z and are labelled “sterile”
Sterile Neutrinos are alsopredicted by a number of theories
APS April 22, 2006 Session C12 3
735 km735 km
Conventional Oscillations
d
u
W+
CC NC
NC Deficit in Predicted energy spectrum is evidence of sterile oscillations
Evisible
X NCX=e,
Evisible
NC
Sterile Oscillations
Evisible
X NCX=e,sterile
Measure Near Predict Far
APS April 22, 2006 Session C12 4
3.5m 1.8m
Monte Carlo
CC
NCCC
NC
Longitudinal Direction
Tra
nsvers
e D
irecti
on
E Resolution:
APS April 22, 2006 Session C12 5
NC (fsterile = 0)
CC (No Osc.)
CC (Osc.)
Conventional Oscillations Sterile Oscillations
NC (fsterile = 0)
(fsterile = 0.3)
(fsterile = 0.5)
m2=0.003 eV2
fsterile = Fraction of Sterile Mixing
CC (Osc.)m2=0.003 eV2
Take a Monte Carlo Far Detector NC energy spectrum with a CC background to study effects of sterile neutrinos
APS April 22, 2006 Session C12 6
Near Detector DataIntense Neutrino Beam, Many Interactions
MINOS NC signal is at low energies.
Have to properly identify Individual interactions
Near Detector is crucial for Extrapolation to Far
1 neutrino spill=10 s
APS April 22, 2006 Session C12 7
CC
NC
Monte Carlo
1 2 3
1-RMS in longitudinal direction from charge weighted center2-Energy per Plane in the 2nd Half of the Event3-Maximum Energy in a 4 Plane Window
dE/dx
[m] [ADC counts] [%]
Can Construct PDFs from 1,2,3
APS April 22, 2006 Session C12 8
Monte Carlo
))log()log(( NCPPPID
PID
CCNC
Percentage of NC Events Retained
Percentage of Events that are Actually NC
Particle IDParticle ID
Select NC-like Spectrum from Particle ID (PID) Cut
APS April 22, 2006 Session C12 9
Monte Carlo
Far Detector Mock Data with m2 = 0.00212 eV2 , fsterile = 0.11
Visible Energy (GeV)
Performed a Chi-squared Fit between “data” and prediction at Far
7.4e20 Protons on Target
fsterile
APS April 22, 2006 Session C12 10
MINOS is a 2 detector experiment where the first detector will predict a NC energy spectrum at the far detector
Current Work Includes Improve Reconstruction of NC events Improve NC/CC Separation Modeling of NC events Studies of systematics
MINOS will provide a sensitive measurement of sterile neutrinos
We currently have 1.4e20 Protons on Target and expect to have a sterile neutrino measurement later this fall
APS April 22, 2006 Session C12 11
Backup
Start backup
APS April 22, 2006 Session C12 12
Monte Carlo
CCNC
Y = Hadronic Energy Deposited / Total Neutrino Energy
CC Events with lots of Hadronic Activity look like NC Events
APS April 22, 2006 Session C12 13