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Two-dimensional observation on TeV Cosmic-ray anisotropy using the Tibet Air Shower Array

Two-dimensional observation on TeV Cosmic-ray anisotropy using the Tibet Air Shower Array. Zhang Yi. For the Tibet AS  collaboration. 2008.9 TeVP. OUTLINE. The Tibet Air shower Array; Analysis method; Sidereal time cosmic rays anisotropy; Solar time cosmic rays anisotropy;

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Two-dimensional observation on TeV Cosmic-ray anisotropy using the Tibet Air Shower Array

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  1. Two-dimensional observation on TeV Cosmic-ray anisotropy using the Tibet Air Shower Array Zhang Yi For the Tibet AS collaboration 2008.9 TeVP

  2. OUTLINE • The Tibet Air shower Array; • Analysis method; • Sidereal time cosmic rays anisotropy; • Solar time cosmic rays anisotropy; • Periodicity search; • Conclusion；

  3. 1. The Tibet Air shower Array ARGO Hall Tibet AS array

  4. The Tibet Air shower Array Geothermal power plant 中尼公路 • Located at an elevation of 4300 m (Yangbajing , China) • Atmospheric depth 606g/cm2 • Wide field of view • High duty cycle (>90%) • Angular resolution (~0.9。) • Data (1997~2005, 37*109) Advantage in measurement of Cosmic ray Large scale anisotropy

  5. Two dimension analysis method Zenith On-source Off-source Off-source ——Global fitting method Zenith belt Equal

  6. 2. Sidereal time anisotropy One-dimensional observation Amplitude～0.1%

  7. Sidereal time anisotropy components ——NFJ model

  8. Tibet analysis in one dimension Tibet analysis Declination ranges.

  9. Tibet measurement in two dimensions The CR anisotropy is fairly stable and insensitive to solar activities. Three Componets： I--------Tail-in; II-------Loss-cone III------Cygnus区；

  10. Celestial Cosmic Ray intensity map in five energy range 4 TeV <12TeV Energy independent >12TeV Fade away 6.2 TeV 12 TeV 50 TeV “Tail-in” effect exists in 50TeV rule out the solar causation 300 TeV

  11. 3. Solar time anisotropy ——Compton-Getting effect ΔI < I > v c = ( a+ 2 ) cos q Due to terrestrial orbital motion around the Sun Differential E spectrum : j E-a 8 V=30km/s,a = 2.7 D.J. Cutler, D.E. Groom, Nature 322, L434 (1986) The amplitude is ~0.04%

  12. Tibet measurement in solar time I ——Compton-Getting effect （12TeV） The solar time anisotropy is table in two intervals with different solar activity The 1D modulation (solid line) is consitent with the expected one (dash line)。

  13. Tibet measurement in solar time II ——Additional effect (4TeV) Preliminary • Kota et al. (icrc0229) Matsushiro With the compton-getting effect subtracted. The amplitude ～0.04%，Preliminary result

  14. 3. Periodicity search in 3 energy ranges • Sidereal semi-diurnal Solar diurnal. Compton-Getting effect • Sidereal-diurnal

  15. 3. Periodicity search With the solar and sidereal time modulation subtracted.

  16. Conclusion • In the sidereal time frame, revealing finer details of the anisotropies components “tail-in” and “loss-cone” and “Cygnus” region direction. • In the solar time frame, Compton-Getting effect is observed in 12.5TeV, An additional modulation appears to exist in case of low energy. • Besides solar, sidereal, semi-sidereal diurnal Variation, no other periodic modulationobserved.

  17. Thank you！ 中意ARGO实验大厅 中日AS探测阵列

  18. Two-dimension Analysis check II ——Observation in other periods Anti sidereal time； Ext-sidereal time； No signal is expected, the amplitude observed is within statistic error.

  19. 原初宇宙线各向异性的实验观测二

  20. 地方恒星时的宇宙线强度变化 Loss-Cone Tail-In max. shifts earlier in the south Tail-In 1) 一些地下μ实验一维观测 Nagashima, Fujimoto, Jacklyn (JGR, 103, 1998) Hall et al. (JGR, 103, 1998)

  21. Galactic Magnetic field Cygnus Galactic Magnetic field3uG Gyromagnetic radius 3TeV  0.001pc (200AU) Galactic cosmic rays lost their directional information, and are nearly isotropic because of the influence of magnetic fields in the Milky Way.

  22. Celestial Cosmic Ray intensity map for 300 TeV Expected Expected Amp= 0.0016 The statistic error 0.00026， 5σ rule out the Compton-Getting effect. These results have an implication that cosmic rays in this energy range is still strongly deflected and randomized by the Galactic magnetic field in the local environment.

  23. Know anisotropy——Compton-Getting effect III 3)Corotaion of the low energy particles The cosmic ray particles would co-rotate with the interplanetary magnetic field (IMF).

  24. Δ I < I > v c = ( a+ 2 ) cos q Know anisotropy——Compton-Getting effect I 1)The solar motion around the Galactic center j E-a 8 Differential E spectrum : V=220km/s,a = 2.7 A.H. Compton and I.A. Getting, Phys. Rev. 47, 817(1935) L.J. Gleeson and W.I. Axford, Ap. Space Sci. 2, 431(1968)

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