In this study, the Geant4 Monte Carlo toolkit was used to simulate energy spectra of neutrons from secondary cosmic radiation at mountain altitudes for the Environmental Research Station “Schneefernerhaus” at the Zugspitze mountain, Germany (2660 m a.s.l.) and for Sphinx astronomical observatory at the Jungfraujoch, Switzerland (3585 m a.s.l.). Simulations were performed with different intra-nuclear cascade models available in Geant4, and the results were compared with those of measurements that had been performed at both locations by means of an Extended-Range Bonner Sphere Spectrometer. Measurement conditions were quite different for both locations – at Schneefernerhaus the measurements had been performed on the flank of a hill in March 2018 with much snow, while at Jungfraujoch the measurements had been performed on top of a steep local hill in September 2018 with much less snow. Despite these differences, agreement between measurement and simulation was reasonable at both locations, especially at neutron energies greater than 20 MeV where the (unknown) hydrogen content of the environment did not influence the neutron fluence much (i.e., results from simulations were 6–22% lower than those from the measurements for the Schneefernerhaus, and were 22–29% lower for Jungfraujoch, depending on intra-nuclear model used in the simulations). The agreement was less favorable for lower energies, where environmental hydrogen (e.g., snow cover, soil moisture) is known to influence the shape of the neutron energy spectrum, because the real conditions of the snow accumulation close to the location of the measurements were not known and, therefore, a detailed description of the real hydrogen environment in the simulations was not possible. When the results simulated using different intra-nuclear cascade models were compared with each other, agreement was found within ±5%, ±15%, ±20%, and ±20%, for cascade, evaporation, epithermal and thermal neutrons, respectively. While the latter results are consistent with those of simulations and measurements at the CERN EU High-Energy Reference Field (CERF) facility published recently, a detailed sensitivity analysis of the influence of environmental hydrogen on neutron energy spectra is required before a final quantitative comparison of measurements and simulations can be made. This sensitivity analysis is presently under way. It is concluded that simulation of energy spectra of neutrons from secondary cosmic rays close to the atmosphere-lithosphere interface, validated by the spectrometer measurements, showed differences of less than 30%, for neutron energies greater than 20 MeV, whatever intra-nuclear cascade model was used in the simulations.

在这项研究中，使用Geant4蒙特卡洛工具包模拟了位于德国楚格峰山（2660 m asl）的环境研究站“ Schneefernerhaus”和位于德国楚格峰的狮身人面像天文台的来自山地二次宇宙辐射的中子能谱。瑞士少女峰（3585 m asl）。使用Geant4中可用的不同核内级联模型进行了模拟，并将结果与​​通过扩展范围Bonner球谱仪在两个位置进行的测量的结果进行了比较。两个地点的测量条件都大不相同-在Schneefernerhaus，测量是在2018年3月在大雪的山坡上进行的，而在少女峰（Jungfraujoch）的测量是在2018年9月在当地陡峭的山顶上进行的，积雪量少得多。尽管存在这些差异，但在两个位置，测量和模拟之间的协议还是合理的，特别是在中子能量大于20 MeV的情况下，环境的（未知）氢含量对中子通量的影响不大（即，模拟结果为6-22）比Schneefernerhaus的测量值低％，而Jungfraujoch的测量值低22–29％，这取决于模拟中使用的核内模型。该协议不适用于低能，因为已知环境氢（例如，积雪，土壤湿度）会影响中子能谱的形状，因为不知道靠近测量位置的积雪的真实状况，因此无法在模拟中详细描述真实的氢气环境。当使用不同的核内级联模型模拟的结果相互比较时，级联，蒸发，超热和热中子的一致性分别在±5％，±15％，±20％和±20％之内。尽管后者的结果与最近发布的CERN欧盟高能参考场（CERF）设施的模拟和测量结果一致，但在最终定量比较ICP之前，需要对环境氢对中子能谱的影响进行详细的灵敏度分析。可以进行测量和模拟。目前正在进行这种敏感性分析。