A muographic study of a scoria cone from 11 directions using nuclear emulsion cloud chambers

IF 1.8 4区地球科学 Q3 GEOSCIENCES, MULTIDISCIPLINARY

Geoscientific Instrumentation Methods and Data Systems Pub Date : 2022-03-22 DOI:10.5194/gi-11-127-2022

S. Miyamoto, Shogo Nagahara, K. Morishima, T. Nakano, M. Koyama, Yusuke Suzuki

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引用次数: 3

Abstract

Abstract. One of the key challenges for muographic studies is to reveal the detailed 3D density structure of a volcano by increasing the number of observation directions. 3D density imaging by multi-directional muography requires that the individual differences in the performance of the installed muon detectors are small and that the results from each detector can be derived without any bias in the data analysis. Here we describe a pilot muographic study of the Izu–Omuroyama scoria cone in Shizuoka Prefecture, Japan, from 11 directions, using a new nuclear emulsion detector design optimized for quick installation in the field. We describe the details of the data analysis and present a validation of the results. The Izu–Omuroyama scoria cone is an ideal target for the first multi-directional muographic study, given its expected internal density structure and the topography around the cone. We optimized the design of the nuclear emulsion detector for rapid installation at multiple observation sites in the field, and installed these at 11 sites around the volcano. The images in the developed emulsion films were digitized into segmented tracks with a high-speed automated readout system. The muon tracks in each emulsion detector were then reconstructed. After the track selection, including straightness filtering, the detection efficiency of the muons was estimated. Finally, the density distributions in 2D angular space were derived for each observation site by using a muon flux and attenuation models. The observed muon flux was compared with the expected value in the free sky, and is 88 % ± 4 % in the forward direction and 92 % ± 2 % in the backward direction. The density values were validated by comparison with the values obtained from gravity measurements, and are broadly consistent, except for one site. The excess density at this one site may indicate that the density inside the cone is non-axisymmetric, which is consistent with a previous geological study.

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核乳化液云室从11个方向对矿渣锥的摄影研究

摘要muographic研究的关键挑战之一是通过增加观测方向的数量来揭示火山的详细三维密度结构。通过多向muography进行的3D密度成像要求所安装的muonde探测器的性能的个体差异很小，并且可以在数据分析中没有任何偏差的情况下导出每个探测器的结果。在这里，我们描述了一项从11个方向对日本静冈县Izu–Omuroyama scoria锥进行的初步摄影研究，使用了一种新的核乳液探测器设计，该探测器经过优化，可在现场快速安装。我们描述了数据分析的细节，并对结果进行了验证。考虑到其预期的内部密度结构和锥体周围的地形，Izu–Omuroyama scoria锥体是第一次多向摄影研究的理想目标。我们优化了核乳液探测器的设计，以便在现场的多个观测点快速安装，并将其安装在火山周围的11个观测点。用高速自动读出系统将显影后的乳胶膜中的图像数字化为分段轨迹。然后重建每个仿真检测器中的μ子轨道。经过轨道选择，包括亮度滤波，估计了μ介子的检测效率。最后，利用μ介子通量和衰减模型推导了每个观测点在二维角空间中的密度分布。观测到的μ介子通量与自由天空中的预期值进行了比较，结果为88 % ± 4. % 在向前的方向和92 % ± 2. % 在向后的方向上。密度值通过与重力测量值的比较进行了验证，除一个场地外，密度值基本一致。这一位置的过度密度可能表明锥体内部的密度是非轴对称的，这与之前的地质研究一致。

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来源期刊

Geoscientific Instrumentation Methods and Data Systems GEOSCIENCES, MULTIDISCIPLINARYMETEOROLOGY-METEOROLOGY & ATMOSPHERIC SCIENCES

CiteScore

3.70

自引率

0.00%

发文量

审稿时长

37 weeks

期刊介绍： Geoscientific Instrumentation, Methods and Data Systems (GI) is an open-access interdisciplinary electronic journal for swift publication of original articles and short communications in the area of geoscientific instruments. It covers three main areas: (i) atmospheric and geospace sciences, (ii) earth science, and (iii) ocean science. A unique feature of the journal is the emphasis on synergy between science and technology that facilitates advances in GI. These advances include but are not limited to the following: concepts, design, and description of instrumentation and data systems; retrieval techniques of scientific products from measurements; calibration and data quality assessment; uncertainty in measurements; newly developed and planned research platforms and community instrumentation capabilities; major national and international field campaigns and observational research programs; new observational strategies to address societal needs in areas such as monitoring climate change and preventing natural disasters; networking of instruments for enhancing high temporal and spatial resolution of observations. GI has an innovative two-stage publication process involving the scientific discussion forum Geoscientific Instrumentation, Methods and Data Systems Discussions (GID), which has been designed to do the following: foster scientific discussion; maximize the effectiveness and transparency of scientific quality assurance; enable rapid publication; make scientific publications freely accessible.