1 / 15

Recent Results from Super-Kamiokande on Atmospheric Neutrino Measurements

Recent Results from Super-Kamiokande on Atmospheric Neutrino Measurements. Choji Saji ICRR,Univ. of Tokyo for the Super-Kamiokande collaboration. ICHEP 2004, Beijing. Contents. Atmospheric neutrino oscillation studies using full Super-Kamiokande I(SK-I) data

arlen
Download Presentation

Recent Results from Super-Kamiokande on Atmospheric Neutrino Measurements

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Recent Results from Super-Kamiokande on Atmospheric Neutrino Measurements Choji SajiICRR,Univ. of Tokyofor the Super-Kamiokande collaboration ICHEP 2004, Beijing Contents • Atmospheric neutrino oscillation studies using full Super-Kamiokande I(SK-I) data • nm  nt oscillation analysis • L/E analysis • 3-flavor analysis • StatusofSuper-Kamiokande II(SK-II)

  2. Zenith angle p, He … , K  Flux(m-2sec-1sr-1GeV-1)   Zenith angle dist. of Atmospheric n flux Atmospheric neutrinos  Downward （L=10~100 km） e± e Upward （L=up to 13000 km） cosq En > a few GeV Up/Down Symmetry

  3. Event classification n energy distribution Fully Contained (E ~1GeV) Partially Contained (E ~10GeV) Stopping (E~10GeV) Through-going (E~100GeV) Atmospheric neutrinos in Super-Kamiokande

  4. 2-flavor oscillation analysis Data set: full SK-I (FC,PC 1489days, up- 1646 days) Improvements: • Expectation - Three dimensional (3D) n flux calculation -  interaction parameters (tuned by K2K data) • Treatment of systematic errors in c2 calculation • Each systematic error source is treated as independent error term(39 error terms)

  5. Zenith angle distributions    2-flavor oscillations Best fitsin22q=1.0, Dm2=2.1x10-3 eV2 Null oscillation ~13000km ~500km ~15km ~13000km ~500km

  6.  2-flavor oscillations Oscillation Analysis Results (FC + PC + UP-m) 10-3 10-2 • Best fit: sin22 =1.0 m2 = 2.1x10-3 eV2 2 = 175.2/177 dof • 90% C.L. region: sin22 > 0.92 1.5 < m2 < 3.4x10-3 eV2 0.7 0.75 0.8 0.85 0.9 0.95 1 Full paper will be soon

  7. Oscillation Decay Decoherence L/E Analysis A first dip should be observed • Direct evidence for oscillations • Strong constraint to oscillation parameters, especially Dm2 value FC single-ring 1/2 oscillation Full oscillation • Expand fiducial volume(FC) • need more statistics • Select events with highresolution in L/E • DL/E < 70% • FC(single, multi-ring) m-like • PC D(L/E)=70%

  8. L/E Distribution Mostly upward 1489.2 days FC+PC Best fit expectation w/ systematic errors Null oscillation MC Mostly downward First dip is seen as expected by neutrino oscillation

  9. Oscillation Decay Decoherence L/E Significance Dc2 (n decay –n oscillation) =11.4 3.4 s Dc2 (n decoherence -n oscillation)=14.6 3.8 s The first dip of the data cannot be explained by other models

  10. standard zenith angle analysis(90%C.L.) L/E Oscillation result Dm2=2.4x10-3,sin22q=1.00 c2min=37.9/40 d.o.f (sin22q=1.02, c2min=37.7/40 d.o.f) 1.9x10-3 < Dm2 < 3.0x10-3 eV2 0.90 < sin22q@ 90% C.L. Strong constraint on Dm2

  11. m3 Dm223 m2 Dm212 m1 3-flavor Oscillation assuming Dm212 = 0　eV2 neutrino oscillation probabilities are described as; P(negnm) = sin2(2q13) x sin2q23 x sin2(1.27Dm2L/E) P(nmgnt) = cos4q13 x sin2(2q23) x sin2(1.27Dm2L/E) P(negne) = 1 - sin2(2q13)x sin2(1.27Dm2L/E) 3 parameters; Dm223= Dm213, q13, q23 Oscillation probability ( cosQ=-0.6) P(nene) matter effect log10(E(GeV))

  12. Dm2 sin2q13 3-Flavor Analysis result (preliminary) sin2q13 Dm2 m3 normal m2 m1 m2 m1 sin2q13 inverted m3 Bestfit: Dm2 = 2.7x10-3ev2, sin2q23 = 0.5, sin2q13 = 0.0 sin2q23 no evidence for non zero q13

  13. SK - II

  14. Status of SK-II Atmospheric Neutrinos Preliminary! SK-II event • 311.5days data (preliminary) • SK-II data are consistent with SK-I • Clear deficit in upward nm

  15. Conclusion SK-I analysis  oscillation • SK-I full data set (FC,PC 1489days, up- 1646days) • Improved MC prediction and oscillation analysis •  allowed region @ 90% C.L. 1.5 < m2 < 3.4x10-3 eV2, sin22 > 0.92 • SK-I final result will be published soon L/E analysis • Evidence for oscillatory signature1.9 < Dm2 < 3.0x10-3 eV2, sin22q > 0.90@90%C.L. 3 - flavor oscillation - no evidence for non zero q13 SK-II analysis is in progress -preliminary data are consistent with SK-I

More Related