MINOS+ Sterile Neutrino Studies J.Thomas UCL J.Evans (UCL), A.Gavrilenko (W&M), M.Matthis...
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Transcript of MINOS+ Sterile Neutrino Studies J.Thomas UCL J.Evans (UCL), A.Gavrilenko (W&M), M.Matthis...
MINOS+ Sterile Neutrino Studies
J.ThomasUCL
J.Evans (UCL), A.Gavrilenko (W&M), M.Matthis (W&M)A.Sousa(Harvard)
UCL
MINOS+ Precision Measurement
• ~3000 CC events/year between 4-10GeV (including energy resolution and efficiencies)
Different experiments
• Reactor experiments (ne disappearance): q14
• MiniBooNE and LSND (ne appearance):q14+q24
• MINOS (NC and nm disappearance) q24+ q34
• MiniBooNE and LSND, CDHS, CFFR (nm dis):q24
• MINOS+ (nm disappearance) : q24
• MINOS+ (NC disappearance) : q24+ q34
Improvements
• MINOS+ Monte Carlo used for this analysis– Previous used reweighted LE events
• Oscillations at the Near Detector are incorporated
• A complete 4-flavour oscillation formula is used to allow lower reach in Dm2
43
– Down to where interference with atmospheric oscillations occurs (Dm2
43 = 2.5x10-3eV2)
MINOS+ advantages
• MINOS+ will have very high statistics– Simulations here use 2 years of neutrinos or 2
years of anti-neutrinos• 2 detector experiment– Normalisation measurement at FD rather than
shape only (MiniBoone, CDHS, CCFR)– Two baselines : 1km and 735km
Thought Simplifications
• Dm221 dependence can be neglected at this L
and E, so
q13 is small (set to 0)
Thought simplifications
• Reactor anomaly allows q14 < ~9o, (small)• so:• End up with:
• Above Dm243 of 10-1eV2 , sin2D41 and sin2D43≈0.5
• And Probability at FD:
Characteristics of Limits
• 10-1<Dm234<1eV2 : FD in fast oscillation mode
and mass squared term averages to ½, so no sensitivity to exact value of Dm2
34
• Dm234 > 1eV2 : Near Detector spectrum affected
leading to more structure to the exclusion region• Dm2
34 > 10eV2 : ND and FD both see fast oscillations, so comparison cancels sensitivity to the effect
MINOS+ θ24
sin2D41≈sin2D43≈0.5 : FD effect
Atmospheric analysis assumed correct!
ND starts fast oscillation too
ND starts to see effect