Ground Level Enhancement Event Monitor (GLEEM)

地面增强事件监视器 (GLEEM)

• 批准号: ST/X002241/1
• 负责人: Michael Aspinall
• 金额: $ 161.69万
• 依托单位: Lancaster University
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2022
• 资助国家: 英国
• 起止时间: 2022 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=ST%2FX002241%2F1
• 关键词: Ground; Level; Enhancement; Event; Monitor

The risks posed by space weather are becoming more widely recognised, and they are now listed on the UK National Risk Register. In particular, hard solar energetic particle (SEP) events containing a substantial flux of particles with energies greater than 300 MeV pose a considerable risk. Ground level neutron monitors detect such solar events, termed ground level enhancement (GLE) events, at the Earth's surface and have done so since the 1940s. Typically there is around one GLE event per year and they have durations from 1 to 12 hours, the largest event observed with instruments was measured in Leeds on 23 February 1956. Besides other ground-detectable space weather phenomena, GLE events have the potential to disrupt critical national infrastructures, such as the power grid, transport (aviation and rail), satellite applications and communications, and safety critical electronic control systems. Deducing space weather radiation at the top of the Earth's atmosphere from measurements made by neutron monitors on the Earth's surface requires a globally distributed network of monitors and models that simulate the physics of particle interactions in the Earth's atmosphere. The Met Office is responsible for reporting space weather risks to government departments and civil aviation, among others, and has recognised that it does not have sufficient capabilities to provide the necessary services for space weather radiation hazards. For example there are only 50 ground level neutron monitors worldwide still operational, none of these are located in the UK. The design of existing monitors and their instrumentation have changed very little over the last sixty years, they rely on detector materials that are either highly toxic (boron trifluoride) or expensive (helium-3), and are large and bulky instruments containing lead shielding.Concerns over the use of these materials in other applications involving neutron detection has led to the development of a plethora of alternative detection technologies. Despite the wide range of alternative neutron detectors now available, very few are suitable for the specific application requirements of ground-level neutron monitoring, where high detection efficiency and several decades of stability are essential. During the design phase, GLEEM evaluated an alternative detector technology (boron coated straws) that promised the greatest potential to fulfil these specific application requirements. This detector technology was developed for unattended safeguards monitoring, among other applications, where similar challenges exist. Our findings showed that, currently, fully modernised helium-3 detectors remain the most viable option. Our new design is optimised for cost savings, compactness and most efficient use of helium-3. It is designed to produce comparable results to a typical monitor in the existing network and is suited for unattended operation in relatively remote locations. The GLEEM implementation phase now aims to commission and demonstrate a prototype network of the new monitor design. The monitor will be deployed and tested at an existing meteorological field site to verify that such instruments can produce comparable results to those from existing ground level neutron monitors, and potentially enhance existing global capabilities. As proof of concept, a network of one complete instrument and one partial instrument will be demonstrated as part of a test deployment, to provide a compatible data stream for incorporation into the Met Office Space Weather Operations Centre (MOSWOC) and feed into the airborne radiation models being developed as part of SWIMMR N2, the NERC funded SWIMMR Aviation Risk Modelling (SWARM) project. Ultimately, GLEEM aims to construct and operate a significantly cheaper instrument, re-introduce monitoring in the UK and facilitate a major increase in space weather monitoring worldwide.

太空天气带来的风险正得到越来越广泛的认识，它们现在已被列入英国国家风险登记册。特别是，含有大量能量大于300 MeV的粒子通量的硬太阳高能粒子（SEP）事件会造成相当大的风险。自20世纪40年代以来，地面中子监测仪在地球表面探测到这种被称为地面增强（GLE）事件的太阳事件。通常每年大约有一次GLE事件，持续时间从1到12小时，1956年2月23日在利兹测量到的仪器观测到的最大事件。除了其他地面可探测的空间天气现象外，GLE事件还有可能破坏关键的国家基础设施，如电网、运输（航空和铁路）、卫星应用和通信，以及安全关键的电子控制系统。根据地球表面中子监测仪的测量结果推断地球大气层顶部的空间天气辐射，需要一个全球分布的监测仪网络和模拟地球大气中粒子相互作用的物理模型。气象局负责向政府部门和民用航空等部门报告空间天气风险，并认识到它没有足够的能力为空间天气辐射危害提供必要的服务。例如，全世界只有50个地面中子监测器仍在运行，其中没有一个位于英国。在过去的60年里，现有的监测仪及其仪器的设计几乎没有变化，它们依赖的探测器材料要么是高毒性的（三氟化硼），要么是昂贵的（氦-3），而且是大型和笨重的仪器，含有铅屏蔽。对这些材料在涉及中子探测的其他应用中的使用的关注导致了大量替代探测技术的发展。尽管现在有很多可供选择的中子探测器，但很少有适合地面中子监测的特定应用要求，在地面中子监测中，高探测效率和几十年的稳定性是必不可少的。在设计阶段，GLEEM评估了一种替代探测器技术（硼涂层吸管），该技术有望最大限度地满足这些特定的应用要求。这种探测器技术是为无人值守的安全监测以及存在类似挑战的其他应用而开发的。我们的发现表明，目前，完全现代化的氦-3探测器仍然是最可行的选择。我们的新设计优化了成本节约，紧凑和最有效地利用氦-3。它的设计目的是产生与现有网络中的典型监视器相当的结果，适合于在相对偏远的位置无人值守的操作。GLEEM实施阶段现在的目标是委托和演示新监视器设计的原型网络。监测仪将在一个现有的气象场址进行部署和测试，以验证这种仪器能否产生与现有地面中子监测仪相当的结果，并有可能提高现有的全球能力。作为概念验证，一个完整仪器和一个部分仪器组成的网络将作为测试部署的一部分进行演示，以提供兼容的数据流，纳入英国气象局空间天气操作中心（MOSWOC），并将其输入正在开发的机载辐射模型中，该模型是由NERC资助的SWIMMR航空风险建模（SWARM）项目的一部分。GLEEM的最终目标是建造和运行一种更便宜的仪器，在英国重新引入监测，并促进全球空间天气监测的大幅增加。