Relativistic Proton Production during the 2001 April 15 Solar Event
Relativistic Proton Production during the 2001 April 15 Solar Event
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2001 年 4 月 15 日太阳事件期间的相对论质子产生
DOI：
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发表时间：
2007
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通讯作者：
J. Humble
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作者：
D. Bombardieri;K. Michael;M. Duldig;J. Humble
2001年4月15日，太阳的极端太阳活动将质子加速为相对论能量，导致在地球上观测到的宇宙射线在地面上增强。GOES 10航天器直接测量了质子通量，地面观测站测量了高能质子的二次响应。我们已经用一种技术模拟了对这一事件的地面反应，这种技术可以推断出高能质子的光谱、到达方向和各向异性。为了研究加速过程，我们采用了理论激波和随机加速度谱形式来拟合航天器和中子监测数据。在随机加速度的情况下，我们使用两种不同的谱形式。第一种（模型A）通过单能注入结合了理想的预加速步骤。第二个（模型B）结合了一个更现实的注入功能，使用直流电场在一个重新连接的中性电流片中的预加速。我们发现，在事件的上升、峰值和下降阶段（分别为14:20、14:30和14:45），120 MeV和10 GeV之间的谱最适合用激波加速度谱形式拟合。这意味着质子被日冕激波或2001年4月15日日冕物质抛射的弓形激波加速到相对论能量。此外，使用更真实的注入函数（模型B）对2000年7月14日太阳事件的重新研究进一步支持了我们早期的发现，即由耗散的中性电流片的磁重联引起的MHD湍流对该事件的相对论性质子产生很重要。
Extreme solar processes at the Sun on 2001 April 15 accelerated protons to relativistic energies, resulting in a ground-level enhancement in cosmic rays observed at Earth. The GOES 10 spacecraft measured the proton flux directly, and ground-based observatories measured the secondary responses to higher energy protons. We have modeled the ground-level response to this event using a technique that deduces the spectrum, arrival direction, and anisotropy of the high-energy protons. To investigate the acceleration process(es), we have employed theoretical shock and stochastic acceleration spectral forms in our fits to spacecraft and neutron-monitor data. In the case of stochastic acceleration, we use two different spectral forms. The first (model A) incorporates an idealized preacceleration step through monoenergetic injection. The second (model B) incorporates a more realistic injection function using preacceleration by DC electric fields in a reconnecting neutral current sheet. We find that at the rise, peak, and decline phases of the event (14:20, 14:30, and 14:45 UT, respectively), the spectrum between 120 MeV and 10 GeV is best fitted by a shock acceleration spectral form. This implies that protons were accelerated to relativistic energies either by a coronal shock or at the bow shock of the 2001 April 15 coronal mass ejection. In addition, reinvestigation of the 2000 July 14 solar event using the more realistic injection function (model B) further supports our earlier findings that MHD turbulence arising from magnetic reconnection from a dissipating neutral current sheet was important in relativistic proton production for that event.