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Study with Sun Shadow Observed by the ARGO -YBJ experiment

祝凤荣 2010.07 @NOA. Study with Sun Shadow Observed by the ARGO -YBJ experiment. Content. ARGO-YBJ experiment Motivation Measurement of IMF with the ARGO Solar magnetic field Summary. ARGO-YBJ collaboration. INFN and Univeristà di Lecce IHEP, Beijing

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Study with Sun Shadow Observed by the ARGO -YBJ experiment

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  1. 祝凤荣 2010.07 @NOA Study with Sun Shadow Observed by the ARGO-YBJ experiment

  2. Content • ARGO-YBJ experiment • Motivation • Measurement of IMF with the ARGO • Solar magnetic field • Summary

  3. ARGO-YBJ collaboration INFN and Univeristà di Lecce IHEP, Beijing INFN and Università “Federico II” di Napoli Shandong University,Jinan INFN Catania, Univ. and INAF/IASF di Palermo South West Jaotong Univ., Chengdu INFN and Università di Pavia Tibet University, Lhasa INFN and Univ.ersità “Tor Vergata” di Roma Yunnan University, Kunming INFN and Università “Roma Tre” di Roma Zhengzhou University INFN and INAF/IFSI di Torino Hongkong University Hebei Normal University Spokesmen Prof. B. D’Ettorre Piazzoli Prof. Cao Zhen

  4. ARGO-YBJis an Extensive Air Shower detector optimized to work with showers induced by primaries cosmic rays of energy E > a few hundreds GeV This low energy thresholdis achieved by: • operating at veryhighaltitude (4300 m) • using a “full coverage” detection surface

  5. Current status • Data taking since Jul. 2006 • Duty cycle ~ 90% • Trigger rate 3.6 kHz • Dead time 3% • 220 GB/day transferred to IHEP

  6. SMMF Sunspot Polar Field Strength IMF 1. Motivation Solar magnetic measurement

  7. ASr result • 1. Sun’s shadow is strongly affected by the solar and interplanetary magnetic fields changing with the solar activity. • 2. Near solar minimum, the displacement of the Sun’s shadow in the east-west direction is mostly caused by the effect of the dipole component of the solar magnetic field. When the dipole directions of the Sun and the Earth are parallel the Sun shadow would shift to west (in 2008-2009), otherwise when they are anti-parallel the two component will cancelled (in 1996-1997). • 3. The displacement in the north-south direction is due to the effect of the IMF. The shadow will be shifted to the north by the away (from the Sun) IMF and to the south by the toward (to the Sun) IMF.

  8. Motivation • Solar surface is measured everyday by ground based detector. But, from surface to 2.6 Rsun, the chromospheres magnetic field measurement is difficult, usually the surface measurement is extrapolated under some hypothesis (Like the PFSS model). Cosmic ray shadow by solar maybe provide some information about the magnetic of this region, like defected ratio. • From 2.5 Rsun to 1 AU, only measurement at 1 AU. The IMF usually is assumed a simple Archimedean spiral configuration as the Sun rotates. Sun shadow displacement could measure the magnetic of this region. • ARGO-YBJ have a higher event rate and wider sensitive energy range , so we could check ASr result, measure sun shadow short term variations and its energy dependence.Our final aim  is to give some independent quantitativemeasurement of the solar magnetic.

  9. Sun shadow of 44.6σ • Clear Off set of the position in N-S • There is almost not off set in E-W. • 6/2006-10/2009 • 906 days • Θ<50 deg • Nhit>100

  10. How the sun shadow shift in IMF? • The sun shadow of 1TeV proton is shift 1.5 degree when only IMF. Tracking the 1 TeV antiproton from earth to sun step by step could find how the sun shadow shift. • When distance <20 Rsun, the IMF effection on sun shadow could be neglected. So 2/3 of the shift is caused by IMF from 120Rsun to 215Rsun. Deflected angle of particle Deflected angle of sun shadow 1 TeV Proton

  11. 太阳整体磁场模型 IMF模型一：草帽 IMF模型二：涡轮

  12. Potential Field Source Surface Model (PFSS) • 势场模型、线性无力场模型和非线性无力场模型是无力场假设下的三种理论外推模型。 • “势场表面源” (PFSS)模型为势场模型： 1、光球以内的太阳内部的磁场受等离子体运动的控制，是磁场通过太阳发电机产生的区域。 2、光球以上的低日冕区存在着闭合的磁力线，假设了区域内的磁场是势场，即该区域的磁场满足Laplace方程。 3、表面源模型认为，当磁场到达约r= 2.5 R0冕层，即所谓的“表面源”时，由于太阳风的作用，磁力线被拉成垂直于表面源，势场假设不再适用，即形成相对于行星际空间来说的所谓源.

  13. 简单模型：阿基米得螺旋线 按400km/s速度摆出来 Carington Coordinate:solar longitudes Carington period: 27.3 days

  14. Nhit>100 Ratio:(12584\14605) 116.06±0.89%（预期遮挡事例数\实际遮挡事例数） 简单考虑角分辨0.76度后缺失度：101.34% WE: -0.30±0.26 deg SN: 0.50±0.56 deg

  15. 不同方位处（2）

  16. 不同方位处（3）

  17. 18 sectors with 20º each Folding with Carington period of 27.3 days

  18. Displacement vs. solar longitudes

  19. Switching between 2-sector and 4-sector

  20. sun shadow displacement in different sector

  21. Measurement of IMF(with a conventional model) • IMF模型（r>5Rsun ） • At 1AU: B0 is the only parameter • B(θ)=B0 sin(θ-θ0) R-3 R-1

  22. Cosmic ray deflection method vs.direct measurements using orbiting detectors

  23. Study about Solar magnetic field displacement Defected ratio

  24. 1o/E(TeV)/nT IMF and dipole affection • Only IMF, N-S the deflected angle as a function of energy 1o/E(TeV)/nT. • Only dipole, W-E deflected angle is not Direct proportion to 1/E(TeV). • But the geomagnetic field affection is Direct proportion to 1/E(TeV). So,the sun shadow for different energy region could confirm the dipole component?

  25. Deficit ratio with PSFF The magnetic around the solar is complicated and dipole hypothesis is too simple. Harmonic coefficients to order 20 for PFSS model is published in web http://wso.stanford.edu/ We use the PFSS model from Rs to 3.25Rs. We choose one data file to do our calculation. When only PFSS, the defected ratio is 80~90% in 2009. 60~70% in 2002. Ratio=50% 2009: ~0.9TeV 2002: ~3.1TeV

  26. S ummary • ARGO-ybj experiment • Measurement of By component of IMF • Solar magnetic field study

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