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arXiv 1107.4887astro-ph.HEhep-ex
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用ARGO-YBJ观测Cosmic Ray月球阴影效应

Observation of the Cosmic Ray Moon shadowing effect with ARGO-YBJ

YBJ Collaboration

摘要:

宇宙射线受到月球的阻碍,预计其方向会出现亏损(所谓的\emph{Moon shadow})。月影是判断空气簇射阵性能的重要工具。事实上,由于地磁场对宇宙射线传播的弯曲效应,阴影中心向西位移,允许设置引发探测器记录的簇射的初级粒子的绝对刚性尺度。此外,阴影的形状允许确定检测器点扩散函数,而在高能量的赤字的位置允许其绝对指向精度的评估。本文介绍了ARGO-YBJ实验在多TeV能区进行的宇宙线月球遮蔽效应的观测结果,具有很高的统计显著性(55个标准差)。本文通过对地月系统中宇宙射线传播的精确蒙特卡罗模拟,分别研究了地磁场和探测器点扩散函数对观测阴影的影响。得到了角分辨率与粒子数和指向精度的关系。通过测量作为粒子多重性函数的向西位移,估算了探测到的簇射的初级能量,从而校准了簇射大小与宇宙线能量之间的关系。通过监测月球阴影的位置和缺陷,每月检查探测器的稳定性。最后,我们以较高的统计精度研究了“白天”/“夜晚”时间的遮蔽效应,寻找可能由太阳风引起的效应。

英文摘要:

Cosmic rays are hampered by the Moon and a deficit in its direction is expected (the so-called \emph{Moon shadow}). The Moon shadow is an important tool to determine the performance of an air shower array. Indeed, the westward displacement of the shadow center, due to the bending effect of the geomagnetic field on the propagation of cosmic rays, allows the setting of the absolute rigidity scale of the primary particles inducing the showers recorded by the detector. In addition, the shape of the shadow permits to determine the detector point spread function, while the position of the deficit at high energies allows the evaluation of its absolute pointing accuracy. In this paper we present the observation of the cosmic ray Moon shadowing effect carried out by the ARGO-YBJ experiment in the multi-TeV energy region with high statistical significance (55 standard deviations). By means of an accurate Monte Carlo simulation of the cosmic rays propagation in the Earth-Moon system, we have studied separately the effect of the geomagnetic field and of the detector point spread function on the observed shadow. The angular resolution as a function of the particle multiplicity and the pointing accuracy have been obtained. The primary energy of detected showers has been estimated by measuring the westward displacement as a function of the particle multiplicity, thus calibrating the relation between shower size and cosmic ray energy. The stability of the detector on a monthly basis has been checked by monitoring the position and the deficit of the Moon shadow. Finally, we have studied with high statistical accuracy the shadowing effect in the "day"/"night" time looking for possible effect induced by the solar wind.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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