S. Miyamoto, Shogo Nagahara, K. Morishima, T. Nakano, M. Koyama, Yusuke Suzuki
{"title":"A muographic study of a scoria cone from 11 directions using nuclear emulsion cloud chambers","authors":"S. Miyamoto, Shogo Nagahara, K. Morishima, T. Nakano, M. Koyama, Yusuke Suzuki","doi":"10.5194/gi-11-127-2022","DOIUrl":null,"url":null,"abstract":"Abstract. One of the key challenges for muographic studies is to reveal the detailed\n3D density structure of a volcano by increasing the number of observation\ndirections. 3D density imaging by multi-directional muography requires that\nthe individual differences in the performance of the installed muon\ndetectors are small and that the results from each detector can be derived\nwithout any bias in the data analysis. Here we describe a pilot muographic\nstudy of the Izu–Omuroyama scoria cone in Shizuoka Prefecture, Japan, from\n11 directions, using a new nuclear emulsion detector design optimized for\nquick installation in the field. We describe the details of the data\nanalysis and present a validation of the results. The Izu–Omuroyama scoria cone is an ideal target for the first\nmulti-directional muographic study, given its expected internal density\nstructure and the topography around the cone. We optimized the design of the\nnuclear emulsion detector for rapid installation at multiple observation\nsites in the field, and installed these at 11 sites around the volcano. The\nimages in the developed emulsion films were digitized into segmented tracks\nwith a high-speed automated readout system. The muon tracks in each emulsion\ndetector were then reconstructed. After the track selection, including\nstraightness filtering, the detection efficiency of the muons was estimated.\nFinally, the density distributions in 2D angular space were derived for each\nobservation site by using a muon flux and attenuation models. The observed muon flux was compared with the expected value in the free sky,\nand is 88 % ± 4 % in the forward direction and 92 % ± 2 % in the backward direction. The density values were validated by\ncomparison with the values obtained from gravity measurements, and are\nbroadly consistent, except for one site. The excess density at this one site\nmay indicate that the density inside the cone is non-axisymmetric, which is\nconsistent with a previous geological study.\n","PeriodicalId":48742,"journal":{"name":"Geoscientific Instrumentation Methods and Data Systems","volume":null,"pages":null},"PeriodicalIF":1.8000,"publicationDate":"2022-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"3","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Geoscientific Instrumentation Methods and Data Systems","FirstCategoryId":"89","ListUrlMain":"https://doi.org/10.5194/gi-11-127-2022","RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"GEOSCIENCES, MULTIDISCIPLINARY","Score":null,"Total":0}
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.
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.