High resolution imaging in the inhomogeneous crust with cosmic-ray muon radiography: The density structure below the volcanic crater floor of Mt. Asama, Japan

Abstract.A model experiment was performed in order to evaluate the spatial resolution and the accuracy of determining the density by utilizing a steel block. The steel block (7.8 g cm −3 ) is 5 m thick along the muon trajectories and weighs about 15 t. By comparing the experimental result with simulations, the density and the width of the steel block were measured as 7.3 ± 1.0 g cm −3 and 37 ± 15 cm, respectively.

Section: Resultsmentioning

confidence: 99%

Evaluation of positioning and density profiling accuracy of muon radiography by utilizing a 15-ton steel block

Tanaka

2013

“…Muon radiography has achieved interesting results on several volcanoes such as Usu (Tanaka and Yokoyama, 2008;, Asama (Tanaka et al, 2007a(Tanaka et al, , 2009a, Satsuma-Iwo-jima (Tanaka et al, 2009b) and other volcanoes (Lesparre et al, 2012). At the same time, the technique itself has advanced rapidly.…”

Section: H K M Tanaka and I Yokoyama: Possible Application Of Commentioning

confidence: 99%

Possible application of compact electronics for multilayer muon high-speed radiography to volcanic cones

Tanaka

Yokoyama²

2013

Abstract. Compact data-taking electronics were developed for high-speed multilayer muon radiography in order to minimize operation failure rates. By requiring a linear trajectory within the position sensitive detectors (PSDs), the background (BG) events produced by vertical electromagnetic (EM) showers are effectively reduced. In order to confirm the feasibility of this method, the system comprising four PSD layers was tested by imaging the internal structure of a parasitic cone and the adjacent craterlets formed in the 1910 eruption at the base of the Usu volcano, Hokkaido with a conventional (MURG08) readout system (Kusagaya et al., 2012;Uchida et al., 2009). The new mountain is believed to be a cryptodome since its formation. As knowledge on lava domes is accumulated at various volcanoes, the definition of "cryptodome" is now doubted in its validity. The results of the preliminary 290 h muon radiographic survey revealed that the "cryptodome" is not underlain by any lava mass and that a main craterlet is accompanied by magma intrusions at shallow depths. The former verifies that the new mountain is not a cryptodome but a volcanogenetic mound, and the latter interprets the phreatic explosions forming the craterlets as intrusions of magma into the aquifer. However, a higher data taking failure rate was observed with a softwarebased MURG08 system when the size of the active area of the detection system was enlarged to improve the detection ability of the system. The newly developed MURG12 is a complete electronics system that can simultaneously process signals from 192 scintillation counters with a data size of 600 kbps ch −1 without operation failure. We anticipate that the observation speed would be further improved by employing MURG12.At the base of the Usu volcano, in the 20th century, four eruptions occurred. Some of them demonstrated three characteristic stages of magma intrusions. First, a magma branch remained at a depth leaving an upheaval of the ground; second, it rose and reached aquifers causing phreatic explosions without extrusions; and third, it reacted with aquifers causing phreatic explosions and further extruded over the ground forming a lava dome. In order to clarify the eruption mechanism of Usu, it is necessary for us to image many parasitic cones. Based on the result of the test measurement, we anticipate that MURG12 would be a strong tool for high-speed muon radiography.

“…Cosmic muons have already been applied for environmental studies, such as measurements of snow depth on mountains , search for hidden chambers in the Kephren Pyramid , and investigation of the inner structure of volcanos Tanaka et al, 2007;Lesparre et al, 2010). All these applications are based on the energy loss of muons, which implies that the measured flux depends on the traversed material.…”

Section: Introductionmentioning

confidence: 99%

CCC-based muon telescope for examination of natural caves

Oláh

Barnaföldi

Hamar

et al. 2012

Abstract.A portable cosmic muon detector has been developed for geophysical applications: searching for large scale underground rock/soil inhomogeneities and underground cavities. The designed muon telescope called a muon tomograph is based on the recently developed closed cathode chamber (CCC) technology, which provides a cheap, easy handling, portable, and power efficient detector system able to work even in extreme conditions (e.g. high humidity, low/high temperature). The muon telescope has a detection surface of approximately 0.1 m 2 with a 10 mrad angular resolution. Tests have been performed in natural caves and artificial tunnel systems as well. In this paper a summary of the first results on tomographic cavities are presented and the geophysical and possible industrial use of the cosmic muon tomographic technology is indicated.