Long Term Modulation of the Galactic Cosmic Radiation

研究人员将确定在超过22年的时间尺度上，哪些物理过程对银河宇宙辐射的时间变化负责，特别强调100年或更大的周期。一个附属目标将是为公元1200-2000年期间发生的“太空天气”建立限制。主要工作是利用1200-2000年期间银河系宇宙辐射时间变化的宇宙成因记录，结合近50年来的中子监测和卫星测量，研究长期（100年时间尺度）调制的物理性质。本研究由几个部分组成。研究人员将限制铍-10和碳-14的变化，因为地磁截止的变化，这是1200-2000年地磁力矩及其矢量方向变化的结果，并开发一种方法来纠正这些影响的数据。他们将利用已知的在1561-1994年间发生的非常大的太阳宇宙射线事件来研究它们对铍和碳数据的贡献，并开发一种方法来消除这种贡献。利用这些结果，他们将从宇宙生成数据中去除地磁截断和太阳宇宙射线效应，留下一个更准确的星系宇宙射线长期调制的代表。这将使他们推断出银河系宇宙辐射能谱的时间变化与从公元1200年到现在观测到的宇宙射线强度的长期变化是一致的。研究人员综合了来自近地和远日球层的卫星数据，将确定产生银河系宇宙辐射长期调制机制的本质。他们将探讨这些结果的天体物理学意义，并建立1200- 2000年空间天气的基准。

The investigators will determine which physical processes are responsible for temporal variations in galactic cosmic radiation with time scales greater than 22 years, with particular emphasis on periods of order 100 years and greater. A subsidiary goal will be to establish limits for the "space weather" that has occurred throughout the period 1200-2000 AD. The main effort is to use the cosmogenic records of the time variation of the galactic cosmic radiation over the period 1200-2000 AD, together with the neutron monitor and satellite measurements over the past 50 years, to investigate the physical properties of the long term (100 year time scale) modulation. This study comprises several components. The investigators will set limits on the changes in beryllium-10 and carbon-14 due to changes in the geomagnetic cutoff, as a consequence of changes in the geomagnetic moment, and its vector direction, 1200-2000 AD, and developing a means to correct the data for these effects. They will use the known occurrence of very large solar cosmic ray events in the interval 1561-1994 to investigate the contributions they have made to the beryllium and carbon data, and to develop a method to remove such contributions. Using these results, they will remove geomagnetic cutoff and solar cosmic ray effects from the cosmogenic data, leaving a more accurate representation of the long-term modulation of the galactic cosmic rays. This will allow them to deduce what temporal changes in the energy spectrum of the galactic cosmic radiation are consistent with the observed long-term changes in cosmic ray intensity from 1200 AD to the present. Synthesizing the work with satellite data from near earth and from the far heliosphere, the investigators will set bounds on the nature of the mechanisms that produce the long-term modulation of the galactic cosmic radiation. They will explore the astrophysical implications of the results and establish benchmarks for space weather 1200- 2000.