Muon tomography

from Wikipedia, the free encyclopedia

The Myonentomografie is an imaging method for three-dimensional imaging of large-volume objects with muons of cosmic radiation .

background

Cosmic rays contribute significantly to the natural background radiation on earth. At sea level, every square meter is penetrated by around 100 muons per second, while muons can even penetrate several kilometers of rock. Depending on the technology used, the absorption and Coulomb scattering of the muons in the object to be imaged is used in muon tomography, making it possible to illuminate even pyramids and volcanoes. The detection of muons is possible with particle detectors , whereby the flight direction of the muon can also be determined depending on the detector.

history

Cosmic ray muons were used as early as 1955 to measure the thickness of the mountains above a tunnel in Australia, the detector used had a very low angular resolution.

In the years 1965–1969 Luis Walter Alvarez tried to find out with the help of a spark chamber whether there were undiscovered chambers in the Chephren pyramid in Egypt.

In 2017, researchers used this technology to find a previously unknown space in the Great Pyramid of Cheops . The Scan Pyramids project, founded by scientists from the three countries Egypt, France and Japan , continues to work on the discovered space, which has a size of around 400 m³. A developer of mini robots that can be steered into corridors less than three centimeters in diameter has now been brought in.

Applications

Volcanic investigation

In 2009 the method was applied to the Iō-dake (硫黄 岳) volcano on the island of Iojima ( Kikai Caldera , Ōsumi Islands ). This made it possible to determine the density distribution of the volcano.

Cleaning up in Fukushima

As part of the clean-up work after the Fukushima nuclear disaster , the whereabouts of the remains of the melted reactor cores in the reactor buildings had to be clarified, but the reactor buildings cannot be entered because of the extreme radiation. As part of a simulation in 2012, the feasibility of mapping the reactor core was shown. In 2015, two 7 × 7 m drift chamber detectors were installed in reactor 1. Three months after the installation of the plant, the first pictures were published, showing that the nuclear fuel is no longer inside the reactor pressure vessel .

Web links

Individual evidence

  1. ^ LW Alvarez: Search for hidden chambers in the pyramids using cosmic rays . In: Science . 167, 1970, pp. 832-9. doi : 10.1126 / science.167.3919.832 . PMID 17742609 .
  2. ↑ Michael Greshko: The mysterious cavity in the Cheops pyramid poses a riddle . nationalgeographic.de , January 8, 2018 (accessed May 4, 2020).
  3. ^ The Scan Pyramids Project. youtube.com, accessed on June 12, 2020 (English, video duration 58 minutes).
  4. ↑ Time Scanners - Secrets in 3D: The Pyramids (duration of the video 43 minutes). In: Documentation. June 12, 2018, accessed June 12, 2020 .
  5. ↑ Look into the hot throat . In: Image of Science . No. 10 , 2009, p. 61 f . ( online ).
  6. ↑ Hiroyuki KM Tanaka, Tomohisa Uchida, Manobu Tanaka, Hiroshi Shinohara, Hideaki Taira: Cosmic ‐ ray muon imaging of magma in a conduit: Degassing process of Satsuma ‐ Iwojima Volcano, Japan . In: Geophysical Research Letters . tape 36 , no. 1 , 2009, doi : 10.1029 / 2008GL036451 .
  7. ↑ Konstantin Borozdin: Cosmic Ray Radiography of the Damaged cores of the Fukushima reactors . In: Physical Review Letters . 109, 2012. arxiv : 1209.2761 . doi : 10.1103 / PhysRevLett.109.152501 .
  8. ^ Imaging the core of Fukushima reactor with muons. (pdf) Los Alamos National Laboratory , January 29, 2015, accessed February 5, 2017 .
  9. ↑ Muon Scan Finds No Fuel In Fukushima Unit 1 Reactor Vessel. Tepco / The Fukushima Project, March 19, 2015, accessed February 5, 2017 .