Collaborative Research: Element Composition of High Energy Solar Particles

位于地理南极的美国阿蒙森-斯科特站的中子监测器自1964年以来一直在运行。这类监测器探测到的中子是宇宙射线(主要是质子和氦原子核)与地球大气层相互作用的副产品。南极是一个独特的高海拔和低地磁截止刚性的位置。这一装置是全世界低能量中子监测网络的关键，也是连接低得多能量的航天器测量的主要环节。这项研究的核心是需要了解探测器对南极辐射环境的响应，特别是确定在中子监测器约50年的运行期间，南极宇宙线强度特殊长期下降的原因。了解这种下降很重要，因为宇宙射线会产生放射性核素，如铍-10，这些放射性核素会被困在冰中，并被用来确定冰芯样品的年龄和地球极地地区的降雨量。对产生率的充分了解对解释这些数据至关重要。南极冰立方中微子观测站最近的开放，特别是冰顶空气簇射阵列，增加了中子观测的价值。除了作为广泛的空气簇射探测器的主要功能外，冰顶还对以前只有中子监测器才能获得的宇宙射线的强度和光谱高度敏感。冰顶和中子监测器是高度互补的，因为前者在绝对意义上更敏感，但对比监测器更高能量的粒子做出反应。冰顶主要对次级粒子的电子成分作出反应，而中子监测器主要对强子成分作出反应。探测器结合在一起不仅可以确定初级粒子的光谱，还可以确定初级粒子的元素组成。扎实的科学、合作努力、国际合作伙伴和前往南极的旅行为实现教育和推广目标提供了理想的机会。在南极运行中子监测器将成为威斯康星大学河瀑布分校的一项本科生活动。为本科生和两年制大学生提供研究经验，将使学生对尖端科学做出有意义的贡献。中子监测数据被其他研究小组广泛使用，应用于宇宙线研究、日地关系、空间气象、气候学、大气物理、地球物理和磁层物理。中子监测器在预测和确定太阳风扰动以及提供与跨极航空有关的地面增强警报方面发挥直接作用。提高预报重大空间气象事件和确定其特征的能力具有直接的社会效益。

The neutron monitor at the U.S. Amundsen-Scott Station, located at the geographic South Pole, has operated since 1964. Neutrons detected by such monitors are byproducts of nuclear interactions of cosmic rays (predominantly protons and helium nuclei) with Earth's atmosphere. South Pole is a unique location at high altitude and low geomagnetic cutoff rigidity. This installation is the lynchpin of the worldwide neutron monitor network at low energies and the primary link to spacecraft measurements at much lower energies. Central to the research is the need to understand the detector response to the radiation environment of the South Pole, particularly to determine the cause of a peculiar secular decline in cosmic rays intensity at South Pole throughout the ~50-year operating period of the neutron monitor. Understanding this decline is important because cosmic rays produce radionuclides such as Beryllium-10 that become trapped in the ice and are used to determine ice-core sample ages and precipitation levels over the Earth's Polar Regions. A full understanding of the production rate is vital to interpreting these data.Recent opening of the IceCube Neutrino Observatory at South Pole, specifically the IceTop air shower array, has increased the value of neutron observation. In addition to its primary function as an extensive air shower detector, IceTop is highly sensitive to the intensity and spectrum of cosmic rays of energy formerly accessible only to the neutron monitors. IceTop and the neutron monitor are highly complementary to each other as the former is more sensitive in an absolute sense but responds to somewhat higher energy particles than does the monitor. IceTop responds primarily to the electronic component of the secondary particles whereas the neutron monitor responds primarily to the hadronic component. Together the detectors can determine not only the spectra but also the element composition of the primary particles.Solid science, collaborative effort, international partners, and travel to Antarctica provide an ideal opportunity to achieve education and outreach goals. Operation of the neutron monitor at South Pole will become an undergraduate activity at University of Wisconsin-River Falls. Providing undergraduate and two-year college students with research experiences will allow students to make meaningful contributions to cutting-edge science.Neutron monitor data are broadly employed by other research groups, with applications in cosmic ray research, solar-terrestrial relations, space weather, climatology, atmospheric physics, geophysics, and magnetospheric physics. Neutron monitors play a direct role in forecasting and specifying solar wind disturbances and in providing Ground Level Enhancement alerts relevant to the transpolar aviation. Improving the capability to forecast and characterize major space weather events has direct societal benefit.