Oscillations results from the MiniBooNE experiment Alexis - PowerPoint PPT Presentation

Oscillations results from the MiniBooNE experiment Alexis Aguilar-Arévalo (ICN-UNAM), for the MiniBooNE collaboration SILAFAE 2010 10 December 2010, Valparaíso, Chile 1

Outlook MiniBooNE Collaboration MiniBooNE Motivation MiniBooNE Description Summary of past Results New Antineutrino Result Future outlook Conclusions 2 A. Aguilar-Arévalo (ICN-UNAM) SILAFAE 2010, Valparaíso, Chile December 6-12, 2010

MiniBooNE motivation ● LSND experiment (Los Alamos) ● Excess of ν e in a ν µ beam: Excess= 87.9 ± 22.4 ± 6 (3.8 σ ) , µ + → e + +  ν µ ● Used stopped pion beam: π + → µ + + ν µ + ν e ν e signature: Cherenkov light from e + with delayed n capture (2.2 MeV γ ) ● Interpreted as 2 ν oscillations: P (  ν µ →  ν e  ) = sin 2 2 θ sin 2 (1.27 ∆ m 2 L/E ) = (0.245± 0.067± 0.045)% 3 A. Aguilar-Arévalo (ICN-UNAM) SILAFAE 2010, Valparaíso, Chile December 6-12, 2010

Implication of the LSND signal In conflict with results from atmospheric and Solar exps. in a model with three ν 's 3 neutrinos ⇒ 2 distinct ∆ m 2 's 3 ∆ m 2 (mass) 2 a t m 2 ∆ m 2 s o l a r 1 ∆ m 2 LSND ≠ ∆ m 2 atm + ∆ m 2 solar ν µ ν e ν τ 4 A. Aguilar-Arévalo (ICN-UNAM) SILAFAE 2010, Valparaíso, Chile December 6-12, 2010

Sterile neutrinos LEP exp's (width of Z 0 ): “Only 3 light active ν 's” 3 active + 1 sterile: 4 ∆ m 2 L S N D 3 (mass) 2 ∆ m 2 a t m 2 ∆ m 2 s o l a r 1 3+1 model: P ( ν µ →ν e ) = sin 2 2 θ sin 2 (1.27 ∆ m 2 L/E) ν µ ν τ ν e ν s 4| U e 4 | 2 | U µ 4 | 2 ∆ m 4 2 1 4 neutrinos ⇒ 3 ∆ m 2 's 5 A. Aguilar-Arévalo (ICN-UNAM) SILAFAE 2010, Valparaíso, Chile December 6-12, 2010

Mini - Boo ster N eutrino E xperiment target /horn decay tunnel absorber dirt detector ν µ →ν e ??? K + π + Booster p Primary beam Secondary beam Tertiary beam (protons) (mesons) (neutrinos) L/E similar to LSND MiniBooNE ~500 m /~500 MeV LSND ~30m / 30 MeV Focused beam, magnetic horn Polarity → neutrinos or anti-neutrinos Cherenkov Detector 6 800 ton mineral oil A. Aguilar-Arévalo (ICN-UNAM) SILAFAE 2010, Valparaíso, Chile December 6-12, 2010

Mini - Boo ster N eutrino E xperiment target /horn decay tunnel absorber dirt detector Detector ν µ →ν e ??? K + ● 541 meters downstream of target π + Booster p ● 3 meter overburden Primary beam Secondary beam Tertiary beam ● 12.2 meter diameter sphere (protons) (mesons) (neutrinos) (10 meter “fiducial” volume) ● Filled with 800 t of pure mineral oil (CH 2 ) L/E similar to LSND (Fiducial volume: 450 t) MiniBooNE ~500 m /~500 MeV ● 1280 inner phototubes, LSND ~30m / 30 MeV ● 240 veto phototubes Focused beam, magnetic horn Simulated with a GEANT3 Monte Carlo Polarity → neutrinos or anti-neutrinos Cherenkov Detector 7 800 ton mineral oil A. Aguilar-Arévalo (ICN-UNAM) SILAFAE 2010, Valparaíso, Chile December 6-12, 2010

Mini - Boo ster N eutrino E xperiment target /horn decay tunnel absorber dirt detector ν µ →ν e ??? K + π + Booster p Primary beam Secondary beam Tertiary beam (protons) (mesons) (neutrinos) L/E similar to LSND (—) (—) P ( ν µ → ν e ) = sin 2 2 θ sin 2 (1.27 ∆ m 2 L/E ) MiniBooNE ~500 m /~500 MeV LSND ~30m / 30 MeV Neutrino Mode: (positive horn polarity) Search for ν µ → ν e with 6.5E20 POT  assumes CP conservation Focused beam, magnetic horn Polarity → neutrinos or anti-neutrinos Antineutrino Mode: (negative horn polarity) Search for  ν µ →  ν e with 5.66E20 POT  direct test of LSND Cherenkov Detector 8 800 ton mineral oil A. Aguilar-Arévalo (ICN-UNAM) SILAFAE 2010, Valparaíso, Chile December 6-12, 2010

Neutrino Flux Neutrino mode: Anti-neutrino mode: ν µ ν µ 93.6 % 15.7 % (WS)  ν µ  ν µ 83.7 % 5.86 % (WS) ν e +  ν e ν e +  ν e 0.6 % 0.57 % Phys.Rev. D79, 072002 (2009) WS: wrong sign Input from HARP π ± production data 9 A. Aguilar-Arévalo (ICN-UNAM) SILAFAE 2010, Valparaíso, Chile December 6-12, 2010

ν and  ν interactions Cross sections modeled with NUANCE event generator (D. casper, U.C. Irvine) MiniBooNE MiniBooNE (T. Katori) (D. Perevalov) (C. Anderson, J. Link) (S. Linden, M. Wilking) NC π 0 CC π + CCQE (MB  ) NC Elastic (MB  ) (MB  ) (MB  ) µ − µ − W + W + π 0 π + n n,p n,p n,p n,p n,p n,p 10 PRL 100 , 032301 (2008) PRD 82 , 092005 (2010) PLB 664 , 41 (2008) PRL 103 , 081801 (2009) PRD 81 , 092005 (2010) PRD 81 , 013005 (2010) ArXiv:1011.3572 (2010) A. Aguilar-Arévalo (ICN-UNAM) SILAFAE 2010, Valparaíso, Chile December 6-12, 2010

Events in MiniBooNE Identification is based on event topology . Uses primarily Cherenkov light but also scintillation light ν µ n → µ - p ν µ p → µ + n ν e n → e - p ν e p → e + n ( - ) ( - ) ν µ n → ν µ p π 0 p n 11 A. Aguilar-Arévalo (ICN-UNAM) SILAFAE 2010, Valparaíso, Chile December 6-12, 2010

Calibration Stability Very stable, Example: Variation in mean energy of Michel electrons within 1% since the beginning of run (2002). Michel e: electron from muon decay at rest Mean Michel e energy ± 1% Frac. Dev. from average 12 A. Aguilar-Arévalo (ICN-UNAM) SILAFAE 2010, Valparaíso, Chile December 6-12, 2010

Experiment stability (A.Aguilar-Arévalo) Period with 1 and 2 absorbers at 25 m taken into account 6.46 × 10 2 0 POT ν mode 5.66 × 10 2 0 POT ν mode Protons from FNAL Booster to MiniBooNE tgt. (Z. Pavlovic) (Z. Pavlovic) 3.39E20 1 st result ν e appearance result 5.66E20 new result (2010) Anti-neutrino data 13 A. Aguilar-Arévalo (ICN-UNAM) SILAFAE 2010, Valparaíso, Chile December 6-12, 2010

MB: result with neutrinos 6.5E20 POT in neutrino mode No excess of events in signal region (E>475 MeV). Rules out 2 ν 's oscillations as LSND explanation (assuming no CP violation) Excluded region 475 MeV (G. Karagiorgi) signal region E>475 MeV 14 PRL 102, 101802 (2009) A. Aguilar-Arévalo (ICN-UNAM) SILAFAE 2010, Valparaíso, Chile December 6-12, 2010

MB: result with neutrinos Region E<475 MeV shows an Anomaly Mediated Neutrino-Photon excess of ν e -like events: interactions at Finite Baryon Density: J.A. 128.8 ± 20.4 ± 38.3 (3 σ ) Harvey, C.T. Hill, R. J. Hill, arXiv:0708.1281 Shape not consistent with 2 ν oscillations CP-Violation 3+2 Model: Maltoni & Schwetz, Magnitude consistent with LSND arXiv:0705.0107; T. Goldman, G. J. Stephenson Jr., B. H. J. McKellar, Phys. Rev. Origin: Unknown. Several possibilities D75 (2007) 091301. Extra Dimensions 3+1 Model: Pas, Pakvasa, 475 MeV (G. Karagiorgi) & 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 New Gauge Boson with Sterile Neutrinos: Ann E. Nelson & Jonathan Walsh, arXiv:0711.1363 15 PRL 102, 101802 (2009) A. Aguilar-Arévalo (ICN-UNAM) SILAFAE 2010, Valparaíso, Chile December 6-12, 2010