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MINOS+ Sterile Neutrino Studies

MINOS+ Sterile Neutrino Studies. J.Thomas UCL 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). Sterile neutrino search.

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MINOS+ Sterile Neutrino Studies

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  1. MINOS+ Sterile Neutrino Studies J.Thomas UCL J.Evans (UCL), A.Gavrilenko (W&M), M.Matthis (W&M)A.Sousa(Harvard) UCL

  2. MINOS+ PrecisionMeasurement • ~3000 CC events/year between 4-10GeV (including energy resolution and efficiencies)

  3. Sterile neutrino search PAC requested update on this

  4. 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 (nmdis):q24 • MINOS+ (nm disappearance) : q24 • MINOS+ (NC disappearance) : q24+q34

  5. 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 Dm243 • Down to where interference with atmospheric oscillations occurs (Dm243 = 2.5x10-3eV2)

  6. 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

  7. Some Mathematics And helpful assumptions (but these not implemented in simulation)

  8. Some Maths

  9. Thought Simplifications • Dm221 dependence can be neglected at this L and E, so q13 is small (set to 0)

  10. 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:

  11. The limits from last PAC MINOS AND MINOS+

  12. MINOS MINOS+(old)

  13. 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 Dm234 • Dm234> 1eV2 : Near Detector spectrum affected leading to more structure to the exclusion region • Dm234> 10eV2: ND and FD both see fast oscillations, so comparison cancels sensitivity to the effect

  14. FD sterile example DM2 factor averages to 0.5 Both atmospheric and sterile dips apparent here

  15. Near Detector Example Systematic error is on ratio of numu to numubar

  16. MINOS+ θ24 ND starts fast oscillation too ND starts to see effect sin2D41≈sin2D43≈0.5 : FD effect Atmospheric analysis assumed correct!

  17. Bottom Line anti-neutrinos neutrinos

  18. Summary • More careful job results in much larger reach • NC additional analysis not yet complete but improvement expected between 10-2eV2and 10-3eV2. • MINOS+ has a world-beating sensitivity to this sterile search for both neutrinos and antineutrinos over large range of mass splitting

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