By TAKAHIRO TAKENOUCHI/ Staff Writer
July 20, 2023 at 08:00 JST
An image, right, and illustration of a test show how cosmic-ray muons that can pass through buildings and solid rock are used and detected. Researchers say the data could be applied to car navigation systems. (Provided by Hiroyuki Tanaka, a professor of elementary particle physics at the University of Tokyo)
Japanese researchers developed a system based on subatomic particles derived from high-energy cosmic rays to locate a person's position underground, something that existing navigation tools like GPS are unable to do.
Scientists from the University of Tokyo and NEC Corp. noted that cosmic-ray muons readily pass through solid rock, offering obvious advantages for use in car navigation systems and self-driving vehicles in underground parking lots or tunnels.
GPS uses radio waves beamed from satellites to triangulate a position, but these signals do not work in underground areas.
Having the technology to accurately pinpoint the location of vehicles will be essential in a driver-less society.
A team led by Hiroyuki Tanaka, a professor of elementary particle physics at the University of Tokyo, tested muons because that type of particle can penetrate bedrock several kilometers thick.
Generated when high-energy particles in space strike the atmosphere above Earth, muons have been used to monitor magma movement in a volcano, detect empty cavities in the Great Pyramid of Giza in Egypt and probe the interior of the stricken Fukushima No. 1 nuclear power plant.
In an experiment, the team set up a detector mounted on a moveable cart in the first basement of a building within the University of Tokyo’s campus in hopes of identifying muons pounding the planet.
Moving the 1-meter-by-1-meter detector 100 meters down a corridor, the scientists discovered muons arrived in the underground area in succession having passed through the structure’s walls.
Data was collected on particles that traversed detecting machines installed beforehand on the building’s sixth floor.
The cart’s movements and location could be determined by analyzing the routes the muons took.
The team said the method’s margin of error was reduced to a few centimeters in the latest round of the test.
The researchers expect their brainchild to be put into practical use after the detector is downsized to be incorporated into a smartphone.
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